ABS vs all disc brakes ?
Jeffrey Chan
asi...@Glue.umd.edu (Ashuraj Sirohi) wrote:
>(a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
All disc brakes just improve brake distances over rear drums. Getting
ABS is totally different. You can still lock up and skid with all
disc brakes. Whenever you get a car with ABS, ABS is on all four
wheels, unlike some trucks which only have it in the rear.
>(b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
I think they needed more proof that ABS saved lives or were more
effective.
>In my case I am certain I would have avoided accidents if I
>did not skid on wet roads. Lets hear what your experiences are.
ABS is good on dry and wet but not snow or gravel.
>ps: i am not talking about traction control here though it would
> be nice to hear opinions about that too.
Traction control can use a combo of your engine's braking as well as
ABS. More expensive traction control systems use ABS. Cheaper ones,
like those on GM cars only use engine braking. As well, GM uses ABS
brakes that do not pulse as many times as other ABS modules. They use
a cheaper alternative to market their cars more. Though they work,
but not as good. Traction control is good, but only when starting off
from a stand still. It reduces slippage and essentially provides
traction, IT IS NOT SKID CONTROL. Mercedes, BMW, and some other car
companies are doing R&D on skid control mechanisms. When going around
a turn, the car applies the brakes on the inside wheels, to avoid
understeer or oversteer. It is much more complicated & expensive than
ABS & traction control but has its similarities (uses ABS module and
some traction control capabilities, more like extension of traction
control).
Jeff
Ashuraj Sirohi
I drive two cars (mine and my wife's).
1. front disc brakes, rear drum (84 corolla)
2. front antilock disc brakes, rear drum (87 accord Lxi)
I am so used to ABS on car 2 that I have had 2 minor accidents
because of skidding (locked wheels) on car 1. My stress response
is to slam the brakes and not pump them for car 1.
Now i am in a position to buy a new(er) car to replace car 1.
(i am looking at integra)
I would like to know
(a) how effective are all disc brakes (both front and rear) as
opposed to ABS (in drive wheels) ?
(b) why did insurance companies recently stop discounting
premiums for vehicles with anti-lock brakes ? do statistics
not favor ABS ?
In my case I am certain I would have avoided accidents if I
did not skid on wet roads. Lets hear what your experiences are.
Ashu
Allen Martin
In <4tbkfo$d...@news.inforamp.net> jc...@inforamp.net (Jeffrey Chan)
writes:
>asi...@Glue.umd.edu (Ashuraj Sirohi) wrote:
>
>>(a) how effective are all disc brakes (both front and rear) as
>> opposed to ABS (in drive wheels) ?
>
>ABS is totally different. You can still lock up and skid with all
>disc brakes. Whenever you get a car with ABS, ABS is on all four
>wheels, unlike some trucks which only have it in the rear.
>
>> premiums for vehicles with anti-lock brakes ? do statistics
>> not favor ABS ?
>
>effective.
>
>>did not skid on wet roads. Lets hear what your experiences are.
>
>
Matthew Au
Ashuraj Sirohi wrote:
> (a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
I don't think you can get ABS in just drive wheels nowadays, only trucks
have 2 wheel ABS. I think in terms of pure stopping distance, four wheel
disc brakes will be more effective than ABS. However, ABS gives you the
advantage of steering and braking at the same time.
> (b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
Well as I have stated earlier, ABS are pretty common nowadays and it
doesn't make sense for insurance companies to offer discounts as
incentives for car buyers to get ABS.
_________________________________________________________________________Matthew Au
(matth...@utoronto.ca)
Andy Dingley
The moving finger of asi...@Glue.umd.edu (Ashuraj Sirohi) having
written:
>I am so used to ABS on car 2 that I have had 2 minor accidents
>because of skidding (locked wheels) on car 1.
>My stress response
>is to slam the brakes and not pump them for car 1.
So stop driving so close to the car in front ! If your driving is so
marginal that the only thing stopping you from regularly having
accidents is ABS, then you need to learn how to drive more safely.
No-one _needs_ ABS. We drove for years without it. ABS isn't there as
something you should use in everyday driving, it's there to protect
you when you do something stupid, like leaving your braking too late,
or driving too fast for the available visibility. IMHO, whenever your
ABS cuts in and you feel the pedal shaking there should be a damn
great light on the dashboard that lights up and says "You screwed up
on that one !". _Every_ time your ABS fires up is a condemnation of
your driving style for having exceeded the limits of available road
friction. ABS doesn't improve grip, it just tries to save your sorry
butt when you do over-cook it.
Who said I was perfect ? I make a hash of it sometimes and go into a
slide. My response differs from yours though in that I don't blame the
vehicle, I blame myself - I'm extremely embarassed about it and try to
resolve not to make the same mistake twice. My accident record is also
rather better than yours.
>(a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
Different solution to a different problem. 4 wheel disks are only of
real benefit to cars with a sizable braking force at the rear. This
usually means lightweight coupes with mid-engines. They give you
better braking without fade, but they're no more resistant to
skidding.
>(b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ?
Because of drivers like you. You get ABS and suddenly it's "deflector
shields up, Scotty". A little box of hydraulics does not mean that you
are now immune to all damage and somehow no longer subject to the laws
of physics - you and your accident record just think that it's so.
>In my case I am certain I would have avoided accidents if I
>did not skid on wet roads.
You can avoid skidding on wet roads by avoiding the need to brake hard
on wet roads. It's not difficult, just keep a clear space in front of
you. When you drive, think to yourself "What would hapen if the guy
two feet in front of me suddenly stopped ?". If the answer is that
you'd ram into the back of them, then you're too damn close !
Kai
jc...@inforamp.net (Jeffrey Chan) wrote:
>asi...@Glue.umd.edu (Ashuraj Sirohi) wrote:
<snipped>
>>(b) why did insurance companies recently stop discounting
>> premiums for vehicles with anti-lock brakes ? do statistics
>> not favor ABS ?
>I think they needed more proof that ABS saved lives or were more
>effective.
The problem may be that many drivers still pump their brakes - which
bypasses the ABS.
Anyway, not all insurance companies have stopped offering discounts. Shop
around if this affects you.
>>In my case I am certain I would have avoided accidents if I
>>did not skid on wet roads. Lets hear what your experiences are.
>ABS is good on dry and wet but not snow or gravel.
<etc>
I've been saved from a couple of embarassing situations by ABS on both wet
and snow covered roads. In both cases I retained the ability to steer the
car.
Kai.
---------------------------------------------------------------
kai...@ix.netcom.com
Disclaimer: They're my opinions, but you're welcome to share...
Aardwolf
ABS will not help if you're simply tailgating, it actually increases
your stopping distance ever so slightly. It just allows you to steer
and not skid.
Aardwolf.
Aardwolf
Kai wrote:
> >ABS is good on dry and wet but not snow or gravel.
>
> <etc>
>
> I've been saved from a couple of embarassing situations by ABS on both wet
> and snow covered roads. In both cases I retained the ability to steer the
> car.
ABS simply increases the stopping distances on new snow and gravel,
generally the only instances in which it does so noticably. It still
allows you to steer however, and the chance of a skid, although
greater, is still made unlikely.
And the MOST capable traction control systems use an entirely seperate
system that interfaces with the engine transmission and brakes.
Aardwolf.
gpo...@msu.oscs.montana.edu
>I would like to know
>
>(a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
Well if you can go for the 4 wheel disk brakes if available. They are musch
more efficient than front disk / rear drum setups. As far as ABS for the
driving wheels, im not sure anyone makes ABS for just two wheels anylonger
(except for maybe the Cavalier and such). Most ABS systems are 4 wheel (3 or 4
channel, usually 3).
>(b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
This discount was dropped because in their surveys ABS did not drastically
reduce accidents. Yeah right. They just noticed that almost every car produced
offeres ABS, and they did not want to "lose" money in discounts. Every study I
have read says that they do reduce accidents (not by much though). They would
work better if the manufactureres offered better 'instructions' as what they
actually do. Most people I have talked to think thay are there to stop them on
ice as if they are on dry pavement (WRONG). They are just there to help steer
in an emergency situation.
>In my case I am certain I would have avoided accidents if I
>did not skid on wet roads. Lets hear what your experiences are.
I love the 4-wheel/3-channel ABS on my Explorer. It has helped me steer clear
of many accidents in snow, ice, rain, gravel, and even dry pavement (irregular
pavement).
/\ /\/\
/ ^\/^\ /\ //\ \ MONTANA STATE UNIVERSITY "Mountains and Minds!"
/ \___/^\// \ ^\______________________________________________________
Paul O'Gorman | 93 Explorer 4x4 / 86 Cougar GS 5.0 HO |
Department Of Electrical Engineering |---------------------------------------|
Gpo...@msu.oscs.montana.edu | Sleeper Car webpage!: |
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^| Truth about Scooby Doo: |
Visit my home page at-------------------> Http://members.aol.com/vrfusion |
------------------------------------------------------------------------------|
Bentley
Kai (kai...@ix.netcom.com) wrote:
: Anyway, not all insurance companies have stopped offering discounts. Shop
: around if this affects you.
Rumor has it that the ABS does in fact help avoid accidents, but after one
occurs, there are few -- if any -- telltale skid marks. Thus, much harder
to prove who is liable. Thus, the insurance companies quickly soured on
ABS.
Dennis Jensen
In article <31f946c6...@news.demon.co.uk>,
din...@codesmth.demon.co.uk (Andy Dingley) wrote:
>The moving finger of asi...@Glue.umd.edu (Ashuraj Sirohi) having
>written:
>
>>I am so used to ABS on car 2 that I have had 2 minor accidents
>>because of skidding (locked wheels) on car 1.
>
>>My stress response
>>is to slam the brakes and not pump them for car 1.
>
>So stop driving so close to the car in front ! If your driving is so
>marginal that the only thing stopping you from regularly having
>accidents is ABS, then you need to learn how to drive more safely.
>
>No-one _needs_ ABS. We drove for years without it. ABS isn't there as
>something you should use in everyday driving, it's there to protect
>you when you do something stupid, like leaving your braking too late,
>or driving too fast for the available visibility. IMHO, whenever your
>ABS cuts in and you feel the pedal shaking there should be a damn
>great light on the dashboard that lights up and says "You screwed up
>on that one !". _Every_ time your ABS fires up is a condemnation of
>your driving style for having exceeded the limits of available road
>friction. ABS doesn't improve grip, it just tries to save your sorry
>butt when you do over-cook it.
>
In general, maybe. But you can be doing braking (nowhere near threshold) and
hit a fairly large bump with one wheel, wheel goes up in the air, click goes
the ABS). Have you done something stupid? No. It is just an instance of ABS
operating where it is not completely necessary. However, I do prefer to have
ABS for the security, especially when the wife is driving the 2 young kids .
Dennis
Timothy P. Banse
ABS does reduces stopping distance. But its primary purpose is to allow
the driver to steer during hard braking. In other words, because the
wheels don't lock up, you don't lose control of the car.
Bob Morris
gpo...@msu.oscs.montana.edu writes:
>>ABS is good on dry and wet but not snow or gravel.
>How do you figure the ABS is not good on snow or gravel?
>I think that is where it shines best. It gives much better steering control in
>the snow than locked upfront wheels on a non-ABS car. When it comes down to it,
>you cannot expect it to stop you in snow, but it sure will allow you to steer
>clear of an accident. If you dont think it helps in snow/gravel/ice, then you
>don't know how to use it correctly.
Not true!
At low speeds in snow (say less than 10 mph) you want the wheels locked
up once you've pointed the car straight. If ABS is on with 50% pulsing duty
cycle ratio then you've only got braking 1/2 the time! Locked wheels on hard
snow or ice are the best you can do: think about it. As long as you're
skidding straight. Pulsing *has* to increase your stopping distance on ice!
After getting my Accord with ABS (they came with my SE in a deal I
could not refuse, along with heated leather seats, heated outside mirrors
etc.) I skidded into intersections twice after hard braking at about 5 mph
the first time there was hard packed snow on the ground.
Luckily there was no-one there.
I had never in my life done that in any car. If I brake hard at 5 mph on
packed hard snow I know how long it will take to stop. With ABS on
I took twice as far to stop and nearly had heart attacks both times.
So, I now do what I have to to make sure ABS is inactive in the winter.
Since in Hondas it's an independent system, there's no problem.
You can figure it out for yourself.
ABS is great in high speed panic stops in dry or wet.
It is never needed under about 10 mph and there is a speed sensor
on some cars to stop it from kicking in at low speeds.
Bob Morris, Professor of Systems Engineering
Bruce Bostwick
Ashuraj Sirohi wrote:
> I would like to know
>
> (a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
My $.02 on this particular question:
I have driven cars with disc/drum, drum/drum, and disc/disc. Never have
driven an ABS car, nor do I ever care to. ;-)
Drum/drum is very demanding of proper adjustment and exceedingly
annoying in all but perfect conditions. Most notably, the dual leading
shoe brakes on the front end usually have only two states when wet or
even damp: *ON* and *OFF*. (VW Beetles and Spridgets are both very
infamous for this!)
Disc/drum is usable since the discs have more predictable
characteristics. I can lock up a disc/drum system, but it's very easy
to avoid if I have developed a good feel for the pedal.
I have *never, under any circumstances* locked up a properly adjusted
disc/disc system, and this is with occasional both-feet-on-the-pedal
panic stops with the adrenaline effect. If the proportioning valve is
properly set, you *cannot* lock them. Period. (OK, you can lock them
up on ice, but why are you driving fast enough on ice to need them?) If
you have any problems with locking them up, it's time to get the valve
adjusted and maybe check for air in one of the circuits. Then again,
above experience was in a Volvo -- your mileage may vary, especially
since these were Girling four-piston calipers ..
My personal opinion, and I will probably hold it until I'm dead of old
age, is that ABS is far more trouble and expense than it's worth. Good
disc venting and decent (i.e. semi-metallic) pad compounds are a much
better way to spend the money.
--
<BGB> http://ccwf.cc.utexas.edu/~lihan/
mailto:li...@ccwf.cc.utexas.edu
Dennis Jensen
In article <4tbkfo$d...@news.inforamp.net>,
>> opposed to ABS (in drive wheels) ?
>
>ABS is totally different. You can still lock up and skid with all
>disc brakes. Whenever you get a car with ABS, ABS is on all four
>wheels, unlike some trucks which only have it in the rear.
>
>> premiums for vehicles with anti-lock brakes ? do statistics
>> not favor ABS ?
>
>effective.
>
>>did not skid on wet roads. Lets hear what your experiences are.
>
>
>> be nice to hear opinions about that too.
>
>ABS. More expensive traction control systems use ABS. Cheaper ones,
>like those on GM cars only use engine braking. As well, GM uses ABS
>brakes that do not pulse as many times as other ABS modules. They use
>a cheaper alternative to market their cars more. Though they work,
>but not as good. Traction control is good, but only when starting off
>from a stand still. It reduces slippage and essentially provides
>traction, IT IS NOT SKID CONTROL. Mercedes, BMW, and some other car
>companies are doing R&D on skid control mechanisms. When going around
>a turn, the car applies the brakes on the inside wheels, to avoid
>understeer or oversteer. It is much more complicated & expensive than
>ABS & traction control but has its similarities (uses ABS module and
>some traction control capabilities, more like extension of traction
>control).
>
>Jeff
>
>
applied to the outside rear wheel, to induce a little oversteer, to balance
things. If the car is oversteering, a little front outside braking is applied.
Dennis
Kenneth Hayes
> How do you figure the ABS is not good on snow or gravel?
requires the wheels to lock. You can find the FAQ concerning ABS at
ftp://ftp.balltown.cma.com/pub/misc/Autos/consumer-questions.text
gpo...@msu.oscs.montana.edu
>ABS is good on dry and wet but not snow or gravel.
How do you figure the ABS is not good on snow or gravel?
I think that is where it shines best. It gives much better steering control in
the snow than locked upfront wheels on a non-ABS car. When it comes down to it,
you cannot expect it to stop you in snow, but it sure will allow you to steer
clear of an accident. If you dont think it helps in snow/gravel/ice, then you
don't know how to use it correctly.
pro...@nortel.ca
In article <4tip41$7...@netra.oscs.montana.edu>, gpo...@msu.oscs.montana.edu writes:
|>
|> >ABS is good on dry and wet but not snow or gravel.
|>
|> How do you figure the ABS is not good on snow or gravel?
|> I think that is where it shines best. It gives much better steering control in
|> the snow than locked upfront wheels on a non-ABS car. When it comes down to it,
|> you cannot expect it to stop you in snow, but it sure will allow you to steer
|> clear of an accident.
I think the person who wrote that was referring to stopping distance. Yes,
ABS gives you steering control, but lengthens stopping distance on snow or
gravel. Locked wheels stop shorter on snow or gravel because they will push
a pile of snow/gravel in front of the locked wheels to help stop the car.
Whereas ABS'ed wheels will just roll over it. Similar phenomenon in ski.
|> If you dont think it helps in snow/gravel/ice, then you
|> don't know how to use it correctly.
Note that he didn't mention "ice". IMHO stopping on ice is hopeless. Nothing,
not even ABS, will save you.
--
Isaac Wong (613) 763-6127 | Compiler Development, Public Carrier Networks
iw...@chat.carleton.ca | NORTEL (Northern Telecom) Ltd., Ottawa.
cm...@freenet.carleton.ca | Dept. of Systems & Computer Engineering
isc...@engsoc.carleton.ca | Carleton University, Ottawa, Canada.
Ashuraj Sirohi
Andy Dingley (din...@codesmth.demon.co.uk) wrote:
: Who said I was perfect ? I make a hash of it sometimes and go into a
: slide. My response differs from yours though in that I don't blame the
: vehicle, I blame myself - I'm extremely embarassed about it and try to
: resolve not to make the same mistake twice. My accident record is also
: rather better than yours.
Well, I am the one who posted the original questions. As for my driving
record it is as clean as it can be. I had accidents because they were
accidents.
What would you do if someone ahead of you brakes suddenly and u r
sandwiched between two cars and don't have any control to steer
out of the situation. My second one was when after rounding a
curve going downhill at 25 mph in rain (with posted limit of 30 mph)
with one lane of oncoming traffic, some asshole is jutting into
my lane waiting to take a right.
Accidents are exactly what they are. You could be in one with no
fault of yours. I hope you understand that before pointing any fingers.
: Because of drivers like you. You get ABS and suddenly it's "deflector
: shields up, Scotty". A little box of hydraulics does not mean that you
: are now immune to all damage and somehow no longer subject to the laws
: of physics - you and your accident record just think that it's so.
: You can avoid skidding on wet roads by avoiding the need to brake hard
: on wet roads. It's not difficult, just keep a clear space in front of
: you. When you drive, think to yourself "What would hapen if the guy
: two feet in front of me suddenly stopped ?". If the answer is that
: you'd ram into the back of them, then you're too damn close !
Well, if the car in front had better brakes than yours, u certainly will
ram into that car. Do u think people are stupid when they pay extra for
ABS ? I wonder if people in UK keep only 2 feet distance between cars.
Ashu
Mike Kohlbrenner
Bob Morris wrote:
>
> ... If you dont think it helps in snow/gravel/ice, then you
> >don't know how to use it correctly.
>
>
> At low speeds in snow (say less than 10 mph) you want the wheels locked
> up once you've pointed the car straight. If ABS is on with 50% pulsing duty
> cycle ratio then you've only got braking 1/2 the time! Locked wheels on hard
> snow or ice are the best you can do: think about it.
Not true!
Let's separate two very distinct situations -- snow and ice. In snow, as
another person has said, plowing snow in front of locked tires can lead to
the shortest stopping distances in many situations. Therefore, ABS is not
better at STOPPING in THESE snow conditions. There are, however, many
situations where this does not apply and ABS would be superior.
On ice, you have a different situation. You do not want to lock up your
tires on ice. The shortest stopping distance on ice is achieved by
threshold braking, where the tires are not sliding, but are about to.
GOOD ABS will acheive this during some percentage (<100) of the time. So,
ABS will NOT stop you sooner than good threshold braking. How good
are you at threshold braking when you are caught off guard by a patch of
ice? I would be willing to bet that most people are not good enough at
threshold braking on ice in a panic situation to beat the performance of
good ABS. Add in the element of directional control and ABS seems to be
superior for most drivers for panic situations.
BTW, where did you get your 50% duty cycle number? I'm a little bit skepticle
that a modern ABS is that bad.
Mike Kohlbrenner
<kohl...@an.hp.com>
Greg Spark
In article <4tauko$3...@mojo.eng.umd.edu>, Ashuraj Sirohi
<mailto:asi...@Glue.umd.edu> wrote:
> (b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
The failure of ABS to dramatically reduce crashes demonstrates what happens
when new technology is introduced without driver education. Braking technique
with ABS is totally different to non-ABS. If non-ABS technique is used with
ABS, braking distances are significantly WORSE than in a non-ABS car.
I think the studies have failed to show crash reduction because crashes avoided
in ABS cars retaining steering control have been offset by crashes occuring in
ABS cars using non-ABS technique resulting in longer braking distances. Pretty
hard to prove though.
Two things are unequivocal (using correct technique of course):
1- ABS braking distances on dry or wet tarmac are less than non-ABS
2- ABS retains steering control
Some people claim they can outperform ABS. This MIGHT be possible in ideal
circumstances by a highly skilled driver with racing experience. In a real
world emergency (small child runs out, car appears in front of you at 70mph) I
very much doubt it. Steering control is about the only thing thats going to
save you and them and only ABS can assure that.
Situations where the ABS comes into action in normal driving are very rare if
you are driving safely (twice in 5 years in my experience). Therefore I
recommend practicing using it on a bit of deserted road now and again.
Two points:
1- pedal pulsation may mean that ABS is functioning on rear wheels but front
wheels may be well short of this so PUSH HARDER STILL to reach the point where
ABS is functioning on the front wheels.
2- in a corner use the maximum possible pedal pressure and let the ABS prevent
wheel lockup. Partial application does not allow the ABS to work for you and is
more likely to result in a sideways skid. If your speed is WAY too much even
ABS won't save you!
The rule with an ABS car is:
JUMP on the pedal as hard and fast as possible and the STAND on the pedal
as hard as possible until the car is stopped or the hazard steered around.
Your driving position should be such that when your leg has depressed the
brake pedal maximally it is still slightly bent at the knee.
--
Greg Spark
spa...@wave.co.nz
Hamilton, New Zealand
Audi A4 1.8Tq MTM 187hp
Brandon Sommerville
On 26 Jul 1996 17:18:16 GMT, asi...@Glue.umd.edu (Ashuraj Sirohi) is
accused of saying:
>(a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
For pure braking ability, four disks are better than disk/drum setups.
A skilled driver can beat ABS every time with threshhold braking, but
this is much harder to do in the wet or in other adverse conditions.
ABS lets you steer as well as brake without thinking about it.
>b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
People with ABS tend to be more confident so drive a little more
recklessly, negating the safety benefits of ABS. So the story goes.
More realistically, most people don't understand how ABS works, so
they pump the brakes instead of just slamming them on, defeating the
ABS in the process. In fact, Mercedes recently developped a braking
system that will stop the car with full braking capacity in a panic
situation, as drivers are normally not up to the task.
Besides, the insurance companies exist for one reason, and that is not
to help you and I.
Brandon
bra...@caseware.com
"Let us not forget the lesson that we can learn from this, Arthur, that man
was not meant to tamper with the four basic food groups"
- the Tick
Gavin Walker
Ashuraj Sirohi wrote:
>
> (a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
Unless you fade your brakes a lot you probably won't notice the
difference between a 4w discs and disc/drum. Drums work very
well they just fade if used agressively.
> (b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
If the cars or the driving skills get better people just push the
limit harder. The ABS gives a security to the drivers so they take
more risks. So the number of accidents are about the same and
ABS is expensive to replace if it's damaged.
--
_--_|\ -|- Gavin Walker
/ \ |
\_.--.*/ <- Canberra, gavin....@dit.csiro.au
v Australia Phone +61-6-2167030 Fax +61-6-2167111
Tom Ivar Helbekkmo
[Ashuraj Sirohi]
> I had accidents because they were accidents.
> What would you do if someone ahead of you brakes suddenly and u r
> sandwiched between two cars and don't have any control to steer out
> of the situation.
I'd be very embarrassed about having put myself into such a stupid
situation. I'd also be very much aware that the resulting crash was
my own stupid fault.
> Accidents are exactly what they are. You could be in one with no
> fault of yours.
Absolutely. Accidents happen. But they usually don't; most crashes
are simple human error. Your description of what happens when the
driver in front of you suddenly slams on the brakes...
> Well, if the car in front had better brakes than yours, u certainly
> will ram into that car.
...is _not_ a description of an accident, but of boneheaded driving on
the part of the driver who rams the car in front. I don't know the
details of your rules and regulations for safe driving, but over here
we have a couple of very good rules that are formal regulations and
very smart ideas:
- Always maintain at least three seconds of separation to the car in
front of you.
- Adjust your speed so that you can stop in one third of the distance
along the road that you have a clear, unobstructed view of.
-tih
Keith M. Ryan
In a previous article, kohl...@an.hp.com (Mike Kohlbrenner) says:
>
>On ice, you have a different situation. You do not want to lock up your
>tires on ice. The shortest stopping distance on ice is achieved by
>threshold braking, where the tires are not sliding, but are about to.
>GOOD ABS will acheive this during some percentage (<100) of the time. So,
>ABS will NOT stop you sooner than good threshold braking. How good
>are you at threshold braking when you are caught off guard by a patch of
>ice? I would be willing to bet that most people are not good enough at
>threshold braking on ice in a panic situation to beat the performance of
>good ABS. Add in the element of directional control and ABS seems to be
>superior for most drivers for panic situations.
For the cost of your average ABS system, your time would be much
better spent at a driving school. It seems that ABS is ONLY effective
after you are stuck in a situation that you should not be into, e.g.
not allowing enough clearance, driving too fast etc.
I seem to reemmber hearing stats showing that ABS does not
have any significant impact upon driver safety, judging by the
non-existance reduction in insurance claims with ABS equipted
vehicles.
--
So there I was, snuggled in the leather seat of my brand new Ferrari
I had the oiled wooden gear shift in one hand, and the leather wrapped Momo in
the other. And, I had the stereo cranking _Born to be Wild_...
Only two problems, I was upside down, and under six feet of water...
Robert Underwood
>What would you do if someone ahead of you brakes suddenly and u r
>sandwiched between two cars and don't have any control to steer
>out of the situation. My second one was when after rounding a
Good defensive driving wouldn't have allowed yourself in that
situation.
>curve going downhill at 25 mph in rain (with posted limit of 30 mph)
>with one lane of oncoming traffic, some asshole is jutting into
>my lane waiting to take a right.
The posted speed limit is for dry full visibility conditions. It
was raining, maybe you should have been going slower than 25?
--
* Rob Underwood * Fleming House Alum '93
* 6500...@ucsbuxa.ucsb.edu
* http://www.ece.ucsb.edu/student/grad/underwood/default.html
John Weiss
On 07/26/96 10:18PM, in message <4tauko$3...@mojo.eng.umd.edu>, Ashuraj Sirohi
<asi...@Glue.umd.edu> wrote:
> I would like to know
>
> (a) how effective are all disc brakes (both front and rear) as
> opposed to ABS (in drive wheels) ?
"Yes."
4-wheel disc brakes will help resist fade in all 4 wheels. ABS will help
prevent skidding of the wheels on which it is working.
There is NO reason to have 2-wheel ABS, other than the mfgr is brain-dead from
marketing types and doesn't offer 4-wheel ABS.
Rear drum brakes obviously work.
The best combo is 4-wheel ABS discs...
> (b) why did insurance companies recently stop discounting
> premiums for vehicles with anti-lock brakes ? do statistics
> not favor ABS ?
>
Early studies did not favor ABS. A more recent study apparently does.
I also found the insurance companies (even the "good" ones) ignore direct
input from their users. I related an incident where ABS saved my wife's life
and that of a family in a van. The insurance company quoted back the
"studies"...
> In my case I am certain I would have avoided accidents if I
> did not skid on wet roads. Lets hear what your experiences are.
>
> Ashu
>
> ps: i am not talking about traction control here though it would
> be nice to hear opinions about that too.
--
John Weiss
Bare Bones BBS, Seattle, WA
206-368-7672
Dennis Jensen
In article <31FD33...@ccwf.cc.utexas.edu>,
Bruce Bostwick <li...@ccwf.cc.utexas.edu> wrote:
>Ashuraj Sirohi wrote:
>> I would like to know
>>
>> (a) how effective are all disc brakes (both front and rear) as
>> opposed to ABS (in drive wheels) ?
>
>
>I have driven cars with disc/drum, drum/drum, and disc/disc. Never have
>driven an ABS car, nor do I ever care to. ;-)
>
>Drum/drum is very demanding of proper adjustment and exceedingly
>annoying in all but perfect conditions. Most notably, the dual leading
>shoe brakes on the front end usually have only two states when wet or
>even damp: *ON* and *OFF*. (VW Beetles and Spridgets are both very
>infamous for this!)
>
>Disc/drum is usable since the discs have more predictable
>characteristics. I can lock up a disc/drum system, but it's very easy
>to avoid if I have developed a good feel for the pedal.
>
>I have *never, under any circumstances* locked up a properly adjusted
>disc/disc system, and this is with occasional both-feet-on-the-pedal
>panic stops with the adrenaline effect. If the proportioning valve is
>properly set, you *cannot* lock them. Period.
This is absolute hogwash. In order to lock brakes, all that you need is for
the torque applied to the wheel by the brake to be larger than the torque that
the tyre will allow the wheel to absorb through friction. Indycars use all
steel disc setups, and you can occasionally see them locking up if they brake
too hard. Same thing with touring car racing and production car racing.
The brake proportioning valve has nothing to do with the maximum braking that
can be applied, it only proportions the braking power between front and rear;
it does not change the total force. If you were unable to lock up your wheels
with "both -feet-on-the-pedal", then I suggest that you get your brakes seen
to, you have a problem.
Dennis
David Gaudine
In article <morris.8...@galileo.sce.carleton.ca>,
Bob Morris <mor...@galileo.sce.carleton.ca> wrote:
>
>At low speeds in snow (say less than 10 mph) you want the wheels locked
>up once you've pointed the car straight. If ABS is on with 50% pulsing duty
>cycle ratio then you've only got braking 1/2 the time! Locked wheels on hard
>skidding straight. Pulsing *has* to increase your stopping distance on ice!
If you lock the wheels on ice, you're history. It feels like the car is
accelerating. If you pump the breaks, or have ABS, you stop. Maybe not
very quickly, but you do stop.
Lloyd R. Parker
Brandon Sommerville (bra...@caseware.com) wrote:
: For pure braking ability, four disks are better than disk/drum setups.
: A skilled driver can beat ABS every time with threshhold braking, but
: this is much harder to do in the wet or in other adverse conditions.
Not necessarily. A driver, skilled or otherwise, can NOT hold each wheel
to the threshhold unless the brakes are perfectly balanced. ABS varies
EACH wheel (or maybe the rears as one); a driver cannot do that without 4
brake pedals. They banned ABS in F1 because it was too effective -- and
those are professional drivers.
Carl Porter
> >have 2 wheel ABS. I think in terms of pure stopping distance, four wheel
> >disc brakes will be more effective than ABS. However, ABS gives you the
> >advantage of steering and braking at the same time.
>
> Four wheel disc can still lock up, it all depends on the car whether it can
> stop in less distance with or without ABS. For some cars the stopping distance
> is longer, and others (probably more than) have shorter stapping distances.
> Most cars that offer 4 wheel disc brakes, offer ABS in the same package.
> Snip:
It's the driver that makes the difference with or without ABS. Most drivers
don't have the experience or skill necessary to apply the brakes at the max available
without locking up. Some can, in their case the current batch of ABS systems causes
them to need more room to stop if they use it. This is because they release pressure
on the brakes several times a second. No pressure no brakes, several times a second
and it takes longer to stop. There are some (still experimental?) systems that use
back pressure on the pedal and some different controls to reduce wheel lockup and
maintain the brakes at maximum. When the bugs are worked out these will be the systems
to use.
Carl Porter
Eric Bin
gpo...@msu.oscs.montana.edu writes:
>How do you figure the ABS is not good on snow or gravel?
>I think that is where it shines best. It gives much better steering control in
>the snow than locked upfront wheels on a non-ABS car. When it comes down to it,
>you cannot expect it to stop you in snow, but it sure will allow you to steer
>clear of an accident. If you dont think it helps in snow/gravel/ice, then you
>don't know how to use it correctly.
I don't know about snow but ABS doesn't work well in gravel because in
gravel the fastest way to stop would be to build up a wall of resistance
in front of your tires. ABS doesn't allow that to happen.
Eric
eb...@sfu.ca
Eric Bin
asi...@Glue.umd.edu (Ashuraj Sirohi) writes:
>What would you do if someone ahead of you brakes suddenly and u r
>sandwiched between two cars and don't have any control to steer
>out of the situation. My second one was when after rounding a
>curve going downhill at 25 mph in rain (with posted limit of 30 mph)
>with one lane of oncoming traffic, some asshole is jutting into
>my lane waiting to take a right.
Can't really comment on the first accident but the second sounds
preventable. Posted limits have little to do with actual safety, they're
only there so that 'enforcement' officials can ding you with a ticket.
Speed selection should be dependent on the risk present in a situation.
The problem is that people tend to underrate the situation and therefore
end up with problems. Perhaps you were going too fast for the
conditions. That's not to say that you were an idiot or anything, alot
of people do that same thing.
Eric
eb...@sfu.ca
Bruce Bostwick
Dennis Jensen wrote:
> This is absolute hogwash. In order to lock brakes, all that you need is for
> the torque applied to the wheel by the brake to be larger than the torque that
> the tyre will allow the wheel to absorb through friction.
And if the brakes are perfectly balanced, the force required to break the tires
loose is *very* large -- the reason the car skids when the brake forces aren't
balanced is that the skidding tire transfers its traction load to the other
three, which usually let go more because of the sudden increase that because of
the total force applied. There are dynamic factors at work here as well,
remember.
> The brake proportioning valve has nothing to do with the maximum braking that
> can be applied, it only proportions the braking power between front and rear;
> it does not change the total force. If you were unable to lock up your wheels
> with "both -feet-on-the-pedal", then I suggest that you get your brakes seen
> to, you have a problem.
I neglected to mention in my previous post that in the panic stop, everything in
the car went flying and a window nearly got broken. It was an *extremely* sudden
stop, and subjected all of the occupants of the car to such force that without
seat belts none of them would have been able to stay in the seats. And in all
that, none of the tires so much as squeaked. Like I said, though, the brake
system was of very good quality and in excellent adjustment, and the tires were
A-traction Michelins. Lesser equipment might well have broken loose.
My point is that ABS is of questionable value, because all it really is is a way
to substitute technology for craft. It does not particularly enhance the
abilities of a skilled driver, and the high-tech gadgetry is more prone to
failure just when you need it most. Remember Murphy's Law? Brakes are one of
his specialties. ;-)
Willem-Jan Markerink
In article <31FE7F...@an.hp.com>,
Mike Kohlbrenner <kohl...@an.hp.com> wrote:
>Bruce Bostwick wrote:
>>
>> ... If the proportioning valve is
>> properly set, you *cannot* lock them. Period.
>
>should be able to lock the tires on dry pavement. Period...
Slightly disagree. If you do it the way I was thought in driving school, you
have a hard time locking up. You should increasingly add pressure to the
brakes, and not stamp on them in a fraction of a second. By gradually
increasing pressure, you let the vehicle dive, and add weight to the front
wheels. When done correctly on dry grabby pavement, you virtually can't lock
the front wheels.
>> (OK, you can lock them
>> up on ice, but why are you driving fast enough on ice to need them?)
>
>Perhaps being caught off guard by a patch of ice in otherwise dry
>conditions? Never had that happen to you? Come live in New England...
>
>How about the first time you try stopping on wet leaves in the fall?
>
>>
>> My personal opinion, and I will probably hold it until I'm dead of old
>> age, is that ABS is far more trouble and expense than it's worth. Good
>> disc venting and decent (i.e. semi-metallic) pad compounds are a much
>> better way to spend the money.
>
>While all of the above may improve the feel of your brakes and improve
>your ability to threshold brake, they will also make it easier to lock
>them, due to better braking capability.
>
>I still contend that ABS is for the real world. The one that real people
>live in. The one where occasionally there are other things on one's mind
>while hurrying to get somewhere. The one where not everyone even knows
>what threshold braking is. The one where people can be surprised by
>real conditions in that real world.
>
>People just have to learn how to use them properly -- that's the key.
Adding to this usefull last alinea: I somehow miss the mentioning of steering
ability under full braking. You'll never get this done with even the most
sensible feet....
Bye,
W.J. Markerink
<w.j.ma...@a1.nl> (a-one & en-el)
The desire to understand
is sometimes far less intelligent than
the inability to understand
Bruce Bostwick
Willem-Jan Markerink wrote:
> Don't talk BS. What if someone wanders into you from the other lane?
> You can't predict everything.
No, but you can predict a lot more than you think. Just take the time and
effort to maintain good situational awareness and keep yourself in a position
where you have plenty of options *in case* someone wanders into you from the
other lane.
> Suppose it is a bright sunny day, and someone wanders into you coming from
> the other direction? And suppose your safest route is braking halfway on road
> and in the ditch? Then be very glad to have ABS.
No, I'd probably use the road surface to get rid of as much speed as possible
(which could be quite a bit!) and then take my chances in the ditch. Grass can
slow you down pretty quick if you're careful. ;-) I'd rather not have ABS
getting in the way of my threshold braking while I have good road to slow down
on, and I'd rather not have it getting confused when it hits the dirt and grass
with highly variable traction coefficients. After all, it can't *see* where the
slick spots are; I can.
> If you want to drive defensive for all this kind of hazards, never leave
> first gear. And even then you're not safe. But you won't need ABS then.
Well, if you want to stay perfectly safe, move into a vault and never leave
home. Then again, there's food poisoning .. Anyway, the point is not to drive
slowly, it's to stay as prepared as possible for the unexpected. You can do a
lot of that, trust me. And believe me, I drive quite fast.
Dennis Jensen
In article <31FE6E...@ccwf.cc.utexas.edu>,
Bruce Bostwick <li...@ccwf.cc.utexas.edu> wrote:
>Willem-Jan Markerink wrote:
>> Don't talk BS. What if someone wanders into you from the other lane?
>> You can't predict everything.
>
>No, but you can predict a lot more than you think. Just take the time and
>effort to maintain good situational awareness and keep yourself in a position
>where you have plenty of options *in case* someone wanders into you from the
>other lane.
>
>> Suppose it is a bright sunny day, and someone wanders into you coming from
>> the other direction? And suppose your safest route is braking halfway on
road
>> and in the ditch? Then be very glad to have ABS.
>
>No, I'd probably use the road surface to get rid of as much speed as possible
>(which could be quite a bit!) and then take my chances in the ditch. Grass
can
>slow you down pretty quick if you're careful. ;-) I'd rather not have ABS
>getting in the way of my threshold braking while I have good road to slow
down
>on, and I'd rather not have it getting confused when it hits the dirt and
grass
>with highly variable traction coefficients. After all, it can't *see* where
the
>slick spots are; I can.
What a brilliant driver you must be; those F1 drivers must be absolutely
terrible, after all, prior to being banned, F1s used ABS. You, I guess, would
have had the team remove ABS so that it didn't interfere with your threshold
braking. Maybe you should have instructed Ayrton Senna, Alain Prost and the
like on threshold braking technique:)
In all seriousness, you obviously don't know much about ABS. ABS only operates
when the wheel has started to lock up, in other words, you have gone beyond
threshold braking, and the ABS has to unlock the locked wheel. With ABS, if
you are perfect with your threshold braking, the ABS will never activate, and
you will just have "normal" brakes.
I reiterate, ABS is for when you have stuffed up your threshold braking, it
won't interfere if your threshold braking has not caused lock up.
Dennis
NMA [Bob M.]
ABS doesn't work as well on snow/gravel because the front wheels can't
create a pile of snow/gravel that ultimately pushes against the tires and
helps you stop. That said, I'd still pay the extra $500 or so for an ABS
system. I'd gladly trade my airbag for an ABS arrangement.
--
National Motorists Association Join the NMA!
n...@motorists.com $29 a year.
http://www.motorists.com Sign up online.
Andy Dingley
The moving finger of asi...@Glue.umd.edu (Ashuraj Sirohi) having
written:
>Well, if the car in front had better brakes than yours, u certainly will
>ram into that car.
Only if you're driving too close to it.
What is "too close" ? - it's when you can't stop without hitting the
car in front. It doesn't matter whether you have good brakes or bad
brakes, the safe distance depends on how long it takes _your_ vehicle
to stop. If you drive around assuming that your car is perfect and
stops instantly, then you're driving unsafely.
Ramming a car that stops suddenly in front of you is _your_ fault,
it's a driving error and it's not an accident, it's driver error.
> I wonder if people in UK keep only 2 feet distance between cars.
No we don't, that's why we have a better safety record than the USA.
cs...@netcom.ca
Willem-Jan Markerink wrote:
>
> In article <31FE7F...@an.hp.com>,
> Mike Kohlbrenner <kohl...@an.hp.com> wrote:
> >Bruce Bostwick wrote:
> >>
> >> ... If the proportioning valve is
> >> properly set, you *cannot* lock them. Period.
> >
> >I have to agree with the other post that said that a good braking system
> >should be able to lock the tires on dry pavement. Period...
>
> Slightly disagree. If you do it the way I was thought in driving school, you
> have a hard time locking up. You should increasingly add pressure to the
> brakes, and not stamp on them in a fraction of a second. By gradually
> increasing pressure, you let the vehicle dive, and add weight to the front
> wheels. When done correctly on dry grabby pavement, you virtually can't lock
> the front wheels.
This technique, although correct, is done under controlled situations.
IMO, this is about UNcontrolled situations. In a panic, how many people do
you think will even think to do this? Particularly when you consider that
when something happens, an immediate (or instant)action is required. Even
with ABS, my understanding is it doesn't engage until it actually senses a
locked wheel or a certain amount of pressure is applied to the brake pedal.
We are not all equal drivers. There are good and bad drivers, new drivers,
old drivers, etc., etc. Also, IMHO, I believe the majority of drivers out there
don't spend a lot of time, if any, getting to know what their vehicle is
actually capable of.
P.S. - How many do you think even look at the owners manual that tells you
about such systems?
Mike Kohlbrenner
Bruce Bostwick wrote:
>
> ... If the proportioning valve is
> properly set, you *cannot* lock them. Period.
I have to agree with the other post that said that a good braking system
should be able to lock the tires on dry pavement. Period...
> (OK, you can lock them
> up on ice, but why are you driving fast enough on ice to need them?)
Perhaps being caught off guard by a patch of ice in otherwise dry
conditions? Never had that happen to you? Come live in New England...
How about the first time you try stopping on wet leaves in the fall?
>
> My personal opinion, and I will probably hold it until I'm dead of old
> age, is that ABS is far more trouble and expense than it's worth. Good
> disc venting and decent (i.e. semi-metallic) pad compounds are a much
> better way to spend the money.
While all of the above may improve the feel of your brakes and improve
your ability to threshold brake, they will also make it easier to lock
them, due to better braking capability.
I still contend that ABS is for the real world. The one that real people
live in. The one where occasionally there are other things on one's mind
while hurrying to get somewhere. The one where not everyone even knows
what threshold braking is. The one where people can be surprised by
real conditions in that real world.
People just have to learn how to use them properly -- that's the key.
Mike Kohlbrenner
<kohl...@an.hp.com>
pro...@nortel.ca
Four-time F1 world champion, the Professor, Alain Prost, didn't like ABS
on his '93 Williams. Perhaps he can easily out-perform ABS? BTW, the reason
F1 banned ABS (and other goodies such as active suspension which changes
ride height automatically, and traction control) was because machines and
computers were doing much of the driving instead of the driver.
Bruce Bostwick
Carl Porter wrote:
> It's the driver that makes the difference with or without ABS. Most drivers
> don't have the experience or skill necessary to apply the brakes at the max available
> without locking up.
It's not that hard; if you are sensitive enough to the deceleration you can find the
maximum and maintain that pedal pressure. The only thing about it is that if you don't
consistently do that (and practice it from time to time!) you forget to do it when you
have to. However, all you're really doing is finding the point where the deceleration
levels off when you increase pedal pressure, and then not going down the backside of that
curve.
Oh, and also, part of good driving technique is anticipating the need for braking
whenever you can. You can usually see the situation develop if you look far enough
ahead..
> There are some (still experimental?) systems that use
> back pressure on the pedal and some different controls to reduce wheel lockup and
> maintain the brakes at maximum. When the bugs are worked out these will be the systems
> to use.
I *definitely* don't want one of these. If it gets to the point where this is all there
is, I'll retrofit.
Willem-Jan Markerink
In article <4tlgi5$m...@ucsbuxa.ucsb.edu>,
6500...@ucsbuxa.ucsb.edu (Robert Underwood) wrote:
>In article <4tjb0a$b...@mojo.eng.umd.edu> asi...@Glue.umd.edu (Ashuraj
>
>>What would you do if someone ahead of you brakes suddenly and u r
>>sandwiched between two cars and don't have any control to steer
>>out of the situation. My second one was when after rounding a
>
>situation.
Don't talk BS. What if someone wanders into you from the other lane?
You can't predict everything.
>>curve going downhill at 25 mph in rain (with posted limit of 30 mph)
>>with one lane of oncoming traffic, some asshole is jutting into
>>my lane waiting to take a right.
>
>The posted speed limit is for dry full visibility conditions. It
>was raining, maybe you should have been going slower than 25?
Suppose it is a bright sunny day, and someone wanders into you coming from
the other direction? And suppose your safest route is braking halfway on road
and in the ditch? Then be very glad to have ABS.
If you want to drive defensive for all this kind of hazards, never leave
first gear. And even then you're not safe. But you won't need ABS then.
Bob Morris
da...@donald.concordia.ca (David Gaudine) writes:
I've lived in Ottawa for 26 years. I've driven a 75 Dart, 73 VW, 83 Prelude,
86 Accord, 91 Accord, 93 Accord. In winter there is very rarely glare ice
but often very hard packed snow. Approaching an intersection at say 5-10 mph
I know that if I start braking "ahead of time" I will slide to a stop
at the correct place. In my '91 Accord the moment it senses the least
bit of relative slip among the 4 wheels it starts pulsing. You're faced
with a choice: lift your foot off the brake or press hard and let the abs
continue. In either case you're a dead duck: your only real choice is
to let the ABS pulse and your stopping distance is doubled! If the
coefficient of friction is non-zero, which it is for hard packed snow,
at slow speeds locked wheels give you the most stopping power you can get.
It's intuitively obvious that pulsing must increase your stopping distance.
After sliding into two intersections I've since disabled the ABS in winter
and never had a problem. The odd time I come to a stop slightly askew,
but at the stop line! This is much better than sliding into the intersection!
LRM
Mike Kohlbrenner
Keith M. Ryan wrote:
>
> For the cost of your average ABS system, your time would be much
> better spent at a driving school.
I have been at plenty of driving schools and practice threshold braking
at track events in dry and wet conditions. I STILL think ABS is worth
it in my everyday driving.
Do you really think this is something that is truly feasible for the
general populace?
> It seems that ABS is ONLY effective
> after you are stuck in a situation that you should not be into, e.g.
> not allowing enough clearance, driving too fast etc.
And YOU have never been in any of the above situations? Come on...
Check out my other post. ABS can prove very valuable to the vast
majority of drivers, as long as they are educated on its proper use.
With time, that will come.
> I seem to reemmber hearing stats showing that ABS does not
> have any significant impact upon driver safety, judging by the
> non-existance reduction in insurance claims with ABS equipted
> vehicles.
Yes, and that has been generally accepted as the fault of improper usage.
And that is also starting to change as people become more familiar
with it.
Mike Kohlbrenner
<kohl...@an.hp.com>
Andrew P. Bajorinas
mor...@galileo.sce.carleton.ca (Bob Morris) wrote:
]da...@donald.concordia.ca (David Gaudine) writes:
]>In article <morris.8...@galileo.sce.carleton.ca>,
]>Bob Morris <mor...@galileo.sce.carleton.ca> wrote:
]>>
]>>At low speeds in snow (say less than 10 mph) you want the wheels locked
]>>up once you've pointed the car straight. If ABS is on with 50% pulsing duty
]>>cycle ratio then you've only got braking 1/2 the time! Locked wheels on hard
]>>snow or ice are the best you can do: think about it. As long as you're
]>>skidding straight. Pulsing *has* to increase your stopping distance on ice!
]>If you lock the wheels on ice, you're history. It feels like the car is
]>accelerating. If you pump the breaks, or have ABS, you stop. Maybe not
]>very quickly, but you do stop.
]I've lived in Ottawa for 26 years. I've driven a 75 Dart, 73 VW, 83 Prelude,
]86 Accord, 91 Accord, 93 Accord. In winter there is very rarely glare ice
]but often very hard packed snow. Approaching an intersection at say 5-10 mph
]I know that if I start braking "ahead of time" I will slide to a stop
]at the correct place. In my '91 Accord the moment it senses the least
]bit of relative slip among the 4 wheels it starts pulsing. You're faced
]with a choice: lift your foot off the brake or press hard and let the abs
]continue. In either case you're a dead duck: your only real choice is
]to let the ABS pulse and your stopping distance is doubled! If the
]coefficient of friction is non-zero, which it is for hard packed snow,
]at slow speeds locked wheels give you the most stopping power you can get.
]It's intuitively obvious that pulsing must increase your stopping distance.
Your intuition is wrong in many cases. Look up the following terms in
a high school physics book:
Coefficient of static friction
Coefficient of kinetic friction
In snow, I agree with you because you can lock the wheels and build
little piles of snow in front of the tires thus increasing your
friction. On most conditions (dry, wet, ice) you want static friction
which is only possible when the tires are rotating.
|----------------------------------------------------------------------------|
| Andrew P. Bajorinas | These opinions are my own and |
| Bajo...@Perkin-Elmer.com | not those of my employer. |
|----------------------------------------------------------------------------|
|"The fact that a believer is happier than a skeptic is no more to the point |
|than the fact that a drunken man is happier than a sober one. The happiness|
|of credulity is a cheap and dangerous quality." George Bernard Shaw |
|____________________________________________________________________________|
Carl Porter
> Braking technique with ABS is totally different to non-ABS.
In a panic situtation most people do exactly what you suggest and apply maximum pressure
to the brakes until stopped.
> > I think the studies have failed to show crash reduction because crashes avoided
> in ABS cars retaining steering control have been offset by crashes occuring in
> ABS cars using non-ABS technique resulting in longer braking distances.
I think the problem is people think that with ABS they can stop faster so that means
they can drive faster. Just like people with four wheel drive thinking that since the
have less trouble getting started in snow/ice they can go faster and won't have problems
stopping.
>
> Two things are unequivocal (using correct technique of course):
> 1- ABS braking distances on dry or wet tarmac are less than non-ABS
> 2- ABS retains steering control
>
> Some people claim they can outperform ABS. This MIGHT be possible in ideal
> circumstances by a highly skilled driver with racing experience. In a real
> world emergency (small child runs out, car appears in front of you at 70mph) I
> very much doubt it. Steering control is about the only thing thats going to
> save you and them and only ABS can assure that.
>
> Two points:
> 1- pedal pulsation may mean that ABS is functioning on rear wheels but front
> wheels may be well short of this so PUSH HARDER STILL to reach the point where
> ABS is functioning on the front wheels.
>
> 2- in a corner use the maximum possible pedal pressure and let the ABS prevent
> wheel lockup. Partial application does not allow the ABS to work for you and is
> more likely to result in a sideways skid. If your speed is WAY too much even
> ABS won't save you!
>
> The rule with an ABS car is:
> JUMP on the pedal as hard and fast as possible and the STAND on the pedal
> as hard as possible until the car is stopped or the hazard steered around.
> Your driving position should be such that when your leg has depressed the
> brake pedal maximally it is still slightly bent at the knee.
> ***WRONG!!!***
ABS is great in PANIC situations, most people are inexperienced and jam on the brakes
causing the tires to skid, lose steering control etc. However, when the ABS is working,
the pressure on the brakes is being released and reapplied several times per second. The
tires are also skidding several times per second if it wasn't the ABS system wouldn't be
sensing it and relieving the pressure. Tire traction follows a curve and when it is
skidding the traction is less than when rolling. You can be on both sides of a curve. In
this case stopping distances will be less if you can maintain wheel spin without
engaging the ABS system because the brakes are applied 100% of the time and traction
will be the same or greater than with the ABS system operating.
With this in mind the proper way to brake with ABS is to depress until the pedal
vibrates then back off until it quits & then ease back into it. This should place you
tires at maximum traction and braking at maximum retardation. If you encounter surface
deviations, oil spots and such, the ABS will then reactivate. Hold the pressure constant
briefly and if pulsation continue repeat the above procedure.
In a corner your procedure will most likely induce a skid as the tire only has
so much traction and one it's starts to skid it will most likely maintain it. ABS
DOESN"T prevent the tires from skidding, it senses it and relieves brake pressure to
stop it briefly. Its best to brake hard before you reach the corner in the first place
and then ease completely off the brakes through the corner. If you are alread in a curve
and must brake then you must feel for the balance in the car as you depress the pedal.
Transfer too much weight to the fronts and the rear end will come around ABS or not.
Generally speaking if the pedal starts to pulsate you've tractive limits for the rear
and need to back off.
Join in with your local autocross group and try this and you will find this to be true.
Carl Porter
'87 Firebird & '92 Camaro
G-stock competitor SCCA Solo II/ Solo Trials
There are some new systems being developed which will change this. Instead of pulsing,
the new systems apply back pressure to the pedal forcing you to back off. When these
become available then you can stand on the pedal.
Brandon Sommerville
On 30 Jul 1996 11:19:10 -0400, lpa...@curly.cc.emory.edu (Lloyd R.
Parker) is accused of saying:
>Brandon Sommerville (bra...@caseware.com) wrote:
>: For pure braking ability, four disks are better than disk/drum setups.
>: A skilled driver can beat ABS every time with threshhold braking, but
>: this is much harder to do in the wet or in other adverse conditions.
>
>Not necessarily. A driver, skilled or otherwise, can NOT hold each wheel
>to the threshhold unless the brakes are perfectly balanced. ABS varies
>EACH wheel (or maybe the rears as one); a driver cannot do that without 4
>brake pedals. They banned ABS in F1 because it was too effective -- and
>those are professional drivers.
F1 drivers are braking at the limit at every corner, not the same as
every day driving. Also removing ABS makes the car more dependent on
the driver, so skill comes back into the equation.
Alot of cars actually have shorter stopping distances with no ABS. I
am not arguing that these are under ideal circumstances with dry roads
and no gravel, but it is possible.
For everyday driving, I would prefer ABS myself, but that is only
because I don't pretend to be a supremely skilled driver.
Brandon
bra...@caseware.com
"Let us not forget the lesson that we can learn from this, Arthur, that man
was not meant to tamper with the four basic food groups"
- the Tick
Lloyd R. Parker
pro...@nortel.ca wrote:
: Four-time F1 world champion, the Professor, Alain Prost, didn't like ABS
: on his '93 Williams. Perhaps he can easily out-perform ABS? BTW, the reason
: F1 banned ABS (and other goodies such as active suspension which changes
: ride height automatically, and traction control) was because machines and
: computers were doing much of the driving instead of the driver.
My point exactly. With ABS, any driver can stop like a pro, every time.
It takes real skill and perfectly balanced brakes to duplicate this
manually. And in a panic stop, who knows how they would react?
Threshhold braking is nice, but can you say for certain you would do it
in a panic stop with, say, a jack-knifed semi across the road as you
round a curve?
Brandon Sommerville
On 30 Jul 1996 08:21:06 +0000, Tom Ivar Helbekkmo <t...@avanse.nhh.no>
is accused of saying:
>[Ashuraj Sirohi]
>
>> I had accidents because they were accidents.
>
>> What would you do if someone ahead of you brakes suddenly and u r
>> sandwiched between two cars and don't have any control to steer out
>> of the situation.
>
>I'd be very embarrassed about having put myself into such a stupid
>situation. I'd also be very much aware that the resulting crash was
>my own stupid fault.
Responsability?! Are you crazy! He should get a lawyer and sue the
person that he hit for stopping so quickly, the person who hit him for
hitting him (emotional trauma, he'll never look at his dog the same
way again), the person who taught him how to drive for not teaching
him about this situation and the people who made his brakes for not
making brakes good enough to stop him!
>> Accidents are exactly what they are. You could be in one with no
>> fault of yours.
>
>Absolutely. Accidents happen. But they usually don't; most crashes
>are simple human error. Your description of what happens when the
>driver in front of you suddenly slams on the brakes...
>
>> Well, if the car in front had better brakes than yours, u certainly
>> will ram into that car.
>
>...is _not_ a description of an accident, but of boneheaded driving on
>the part of the driver who rams the car in front. I don't know the
>details of your rules and regulations for safe driving, but over here
>we have a couple of very good rules that are formal regulations and
>very smart ideas:
How can you expect a driver to pay attention to what is going on
around him? The radio probably just started playing Guns and Roses so
he had to change the channel!
>- Always maintain at least three seconds of separation to the car in
> front of you.
>
>- Adjust your speed so that you can stop in one third of the distance
> along the road that you have a clear, unobstructed view of.
>
>-tih
Drive sensibly?! Why should I? I can drive perfectly!
Gotta love today's mentality, eh folks.
Vitalstatistix
In article <4th7iv$f2s...@mel.dit.csiro.au> d.je...@geel.dwt.csiro.au (Dennis Jensen) writes:
>In article <31f946c6...@news.demon.co.uk>,
> din...@codesmth.demon.co.uk (Andy Dingley) wrote:
>>The moving finger of asi...@Glue.umd.edu (Ashuraj Sirohi) having
>>written:
>>
>>>I am so used to ABS on car 2 that I have had 2 minor accidents
>>>because of skidding (locked wheels) on car 1.
<snip>
>>So stop driving so close to the car in front ! If your driving is so
<snip>
>>
>In general, maybe. But you can be doing braking (nowhere near threshold) and
<snip>
>ABS for the security, especially when the wife is driving the 2 young kids .
>Dennis
Just out of curiosity, would ABS have helped me in the following situation:
I was going about 40 mph when a old lady in front of me decided to make an
abrupt right turn without warning. I was not tail gating, but perhaps
following more closely than I should have. Hit the brakes and the car simply
would not stop. I had time to pump the brake several times and nothing
happened. Ended up bumping the lady in front causing minor damage to her rear
bumper and tail lights. Unfortunately for me, the driver behind me had the
same problem and ended up rear ending me (causing the demise of my beloved 89
CRX Si). When we got down from the car, we noticed that the right side of
the road was "caked" with concrete/asphalt and quite different from the left
side. Would ABS help under these conditions?
Krish
Lloyd R. Parker
Carl Porter (3C...@MSG.TI.COM) wrote:
:
: It's the driver that makes the difference with or without ABS. Most drivers
: don't have the experience or skill necessary to apply the brakes at the max available
: on the brakes several times a second. No pressure no brakes, several times a second
: and it takes longer to stop.
Not so. ABS doesn't totally release the pressure, it just backs off to
eliminate lock-up. Threshhold braking is only useful if your brakes are
perfectly balanced and you can hold ALL 4 at that point. Generally, you
can't -- you'd need 4 brake pedals, one for each wheel, to do that. Read
some articles in C/D for example -- these are professional testers, and
they pan non-ABS systems for taking LONGER to stop.
Carl Porter
> I have *never, under any circumstances* locked up a properly adjusted
> disc/disc system, and this is with occasional both-feet-on-the-pedal
> panic stops with the adrenaline effect. If the proportioning valve is
> properly set, you *cannot* lock them. Period.
>
> age, is that ABS is far more trouble and expense than it's worth. Good
> disc venting and decent (i.e. semi-metallic) pad compounds are a much
> better way to spend the money.
If you can't lockup your brakes then your brakes aren't good enough. A properly adjusted
system will lock front and rear brakes at the same time. If the system won't lock up,
you can't be sure that your getting maximum braking capability. It is a requirement on
all race cars that there be sufficient brake power to lock-up the tires regardless of
the tire size or compound just for this reason.
ABS are great for PANIC situations and inexperienced drivers. It they can help the
teenager that's haulin ass in his Mustang avoid hitting my Firebird then it's definitely
worthwhile. Be even better if a trip to The Skip Barber Racing School or Bob Bondurant
was required/included before Mommy and Daddy buy their kiddo a 300 hp rocket. Yes, this
applied to me also when Daddy gave me his 390hp LTD.
Carl Porter
Randy Pafford
In article <x0spaa6...@avanse.nhh.no>, Tom Ivar Helbekkmo <t...@avanse.nhh.no> writes:
|> [Ashuraj Sirohi]
|>
|> > I had accidents because they were accidents.
|>
|> > What would you do if someone ahead of you brakes suddenly and u r
|> > sandwiched between two cars and don't have any control to steer out
|> > of the situation.
|>
|> I'd be very embarrassed about having put myself into such a stupid
|> situation. I'd also be very much aware that the resulting crash was
|> my own stupid fault.
|>
|> > fault of yours.
|>
|> Absolutely. Accidents happen. But they usually don't; most crashes
|> are simple human error. Your description of what happens when the
|> driver in front of you suddenly slams on the brakes...
|>
|> > Well, if the car in front had better brakes than yours, u certainly
|> > will ram into that car.
|>
|> ...is _not_ a description of an accident, but of boneheaded driving on
|> the part of the driver who rams the car in front. I don't know the
|> details of your rules and regulations for safe driving, but over here
|> we have a couple of very good rules that are formal regulations and
|> very smart ideas:
|>
|> front of you.
|>
|> - Adjust your speed so that you can stop in one third of the distance
|> along the road that you have a clear, unobstructed view of.
Fine rules, and I think many accidents could be avoided if people
would maintain proper distance [especially the ones that think they are
such super alert drivers that tailgating is no additional risk] BUT
in heavy traffic on many roads, it is literally impossible to
adhere to the two suggestions above. It just can't be done.
I can't believe the number of people who think that if _they_
just drive "correctly" then accidents will be avoided . . . it only
works if both parties do it right. You are always at some risk
from other stupid drivers [which is not to suggest one shouldn't
strive to reduce one's own stupid mistakes].
Just to make one example, you are driving along, keeping your
distance and all, and somebody in the other lane shifts to your
lane RIGHT IN FRONT OF YOU. It happens. Yes, it's really foolish
on the part of the other driver. No, there is absolutely nothing
you could have done about it [except read the mind of the other driver].
All things like ABS try to do is give extra safety margins in some
situations -- wet roads, etc.
Randy
Henri R Helanto
6500...@ucsbuxa.ucsb.edu (Robert Underwood) writes:
>Good defensive driving wouldn't have allowed yourself in that
>situation.
Defensive driving or not, avoiding some situations is impossible.
As long as there's even *one* driver besides you in existence,
there's no way for you to be absolutely sure that something you
do *will* keep you out of an accident. Even though chances are
that it will, it isn't likely in a 'sandwich' -situation.
>The posted speed limit is for dry full visibility conditions. It
>was raining, maybe you should have been going slower than 25?
Posted speed limits are the legislator's idea of how fast any
driver can drive in any kind of a car in average visibility
and weather conditions, let's not forget that. Personally, I
don't consider speeds well in excess of 100mph particularly
unsafe in fair-to-good weather & visibility when the density
of traffic permits. The key factors for deciding to drive
slower than the speed limit are weather and visibility, unless
you do it because you feel more comfortable with lower speeds.
-Henri
--
###### Henri Helanto ### he...@muncca.fi / hhel...@vipunen.hut.fi
##### Architecture Major #### Nissan Skyline GT-R 'Janspeed Special'
#### Net Admin ##### '71 LS-6 454 Corvette Coupe
### Sports Car Enthusiast ###### Fiat Uno Turbo - 'AARGH! Front wheel drive!'
Aardwolf
Henri R Helanto wrote:
> Posted speed limits are the legislator's idea of how fast any
> driver can drive in any kind of a car in average visibility
> and weather conditions, let's not forget that. Personally, I
> don't consider speeds well in excess of 100mph particularly
> unsafe in fair-to-good weather & visibility when the density
> of traffic permits. The key factors for deciding to drive
> slower than the speed limit are weather and visibility, unless
> you do it because you feel more comfortable with lower speeds.
Exactly--perhaps in some residential areas they may be too FAST?
I think the other main factor you forgot about is the road itself.
Try doing 100+ in some of the switchbacks going up into the Black
Hills---hell try doing over 40 in most cars--and you'll most likely be
thrown off the road and end up a couple hundred feet below where you
wanted to be, smashed to bits at the bottom of a rock-covered slope.
Aardwolf.
Leroy Curtis
In article <4tl0gv$d...@madeline.INS.CWRU.Edu>, "Keith M. Ryan"
<km...@po.CWRU.Edu> writes
>
>
>
> For the cost of your average ABS system, your time would be much
>after you are stuck in a situation that you should not be into, e.g.
>not allowing enough clearance, driving too fast etc.
What about those situations where someone pulls out in front of you on a
roundabout, or from a side turning when you are on a major road? Some
people seem incapable of seeing you even when you are right on top of
them (a good case for DRLs perhaps).
>
> I seem to reemmber hearing stats showing that ABS does not
>have any significant impact upon driver safety, judging by the
>non-existance reduction in insurance claims with ABS equipted
>vehicles.
Can there be any statistics about non-accidents? It is only the
accidents that happened that are recorded, not the accidents that are
avoided.
Regards
Leroy Curtis Le...@baram.demon.co.uk
Mail sent via Demon Internet
Ed McCrudden
In article <umhlynka.838836739@antares>,
Markian Denis Hlynka <umhl...@cc.umanitoba.ca> wrote:
>Um, excuse me. I live in Winnipeg, Manitoba. Our yearly temperatures
>range from -50 Celcius to +45 Celcius.
Say what? When has it ever been +45C in Winnipeg? Methinks thou doth
exaggerate just a tad.
Keith M. Ryan
In a previous article, asi...@Glue.umd.edu (Ashuraj Sirohi) says:
>
>Well, I am the one who posted the original questions. As for my driving
>record it is as clean as it can be. I had accidents because they were
>accidents.
>
>What would you do if someone ahead of you brakes suddenly and u r
>sandwiched between two cars and don't have any control to steer
>out of the situation. My second one was when after rounding a
>curve going downhill at 25 mph in rain (with posted limit of 30 mph)
>with one lane of oncoming traffic, some asshole is jutting into
>my lane waiting to take a right.
No, these both are *EXCELLENT* examples of driver error,
bordering on wreckless driving.
The first is not maintaining a proper following distance behind
the car infront of you. It doens't matter if the person infront of you does athe
fastest 60mph to 0 emergency brake.. *YOU* have the responsiblity to follow at a
safe distance.
The second is also an excellent example: too many people
travel faster than visibility/conditions allow. If you are going
to fast for you to have proper warning to brake, it is YOUR fault.
Same thing happens every winter in the north..
>Accidents are exactly what they are. You could be in one with no
>fault of yours. I hope you understand that before pointing any fingers.
Yes, but your two examples are NOT examples of these.
>
>Well, if the car in front had better brakes than yours, u certainly will
>ram into that car. Do u think people are stupid when they pay extra for
Hmm.. I upgraded my brakes wiht Stillen crossdrilled rotors,
pads etc.. what have *YOU* done?
--
So there I was, snuggled in the leather seat of my brand new Ferrari
I had the oiled wooden gear shift in one hand, and the leather wrapped Momo in
the other. And, I had the stereo cranking _Born to be Wild_...
Only two problems, I was upside down, and under six feet of water...
Ken Stewart
>> Suppose it is a bright sunny day, and someone wanders into you coming from
>> the other direction? And suppose your safest route is braking halfway on road
>> and in the ditch? Then be very glad to have ABS.
>No, I'd probably use the road surface to get rid of as much speed as possible
>(which could be quite a bit!) and then take my chances in the ditch. Grass can
>slow you down pretty quick if you're careful. ;-) I'd rather not have ABS
>getting in the way of my threshold braking while I have good road to slow down
>on, and I'd rather not have it getting confused when it hits the dirt and grass
>with highly variable traction coefficients. After all, it can't *see* where the
>slick spots are; I can.
I watched a car show (AUTOMAG PLUS) where a professional driver
tested his skills on a 240SX (I think) with and without ABS enabled.
The tests included collision avoidance on a wet surface and emergency
braking where you have to move partly off the road.
Using the threshold braking technique he was unable to make the
maneuvers. They also showed how much worse it was to just lock the
wheels.
In the first collision avoidance tests...
As you turn and the car's weight shifts the tires get different amounts of
traction (not to mention the fact that a wet surface isn't going to have a
homogeneous traction coeffiecient anyways). This is where ABS shines because
it brakes the wheels individually. Threshold braking cannot do this.
In the second test where he tried to stop half on the road...
Well ABS shines here too because the wheels on the pavement have great
traction compared to the wheels in the gravel or grass. If he threshold
braked to the point just before the wheels with poor traction locked
then he took much much longer to stop. Braking beyond that point caused
the off road wheels to lock and drag the car off the road.
As for getting confused, well these systems can process wheel conditions
much faster than any human can but of course, its the human who should
usually be able to avoid getting into these conditions.
>My point is that ABS is of questionable value, because all it really is is a way
>to substitute technology for craft. It does not particularly enhance the
>abilities of a skilled driver, and the high-tech gadgetry is more prone to
>failure just when you need it most. Remember Murphy's Law? Brakes are one of
>his specialties. ;-)
I feel that ABS has some big benefits although many people don't get much
out of it because they don't know how to use it or because they start relying
on it.
regards,
Ken
Eric Bin
Leroy Curtis <Le...@baram.demon.co.uk> writes:
>What about those situations where someone pulls out in front of you on a
>roundabout, or from a side turning when you are on a major road? Some
>people seem incapable of seeing you even when you are right on top of
>them (a good case for DRLs perhaps).
These situations should call for caution in the first place. A person
should be prepared for the worst.
Eric
eb...@sfu.ca
Peter Zangl
Carl Porter wrote:
> ABS is great in PANIC situations, most people are inexperienced and jam on the brakes
> causing the tires to skid, lose steering control etc. However, when the ABS is working,
> the pressure on the brakes is being released and reapplied several times per second. The
> tires are also skidding several times per second if it wasn't the ABS system wouldn't be
> sensing it and relieving the pressure. Tire traction follows a curve and when it is
> skidding the traction is less than when rolling. You can be on both sides of a curve. In
> this case stopping distances will be less if you can maintain wheel spin without
> engaging the ABS system because the brakes are applied 100% of the time and traction
> will be the same or greater than with the ABS system operating.
> With this in mind the proper way to brake with ABS is to depress until the pedal
> vibrates then back off until it quits & then ease back into it. This should place you
> tires at maximum traction and braking at maximum retardation. If you encounter surface
> deviations, oil spots and such, the ABS will then reactivate. Hold the pressure constant
> briefly and if pulsation continue repeat the above procedure.
Sorry to blow your bubble, but this is totally wrong. ABS doesn't release
pressure fully. If one wheel is about to roll slower than it should be,
the pressure on this wheel is released until it rolls with normal speed.
Then the pressure will softly be increased till the wheel is about to block
again. So the deceleration is nearly optimal. NO driver is able to do this
better than a ABS (except some crap in some cheap cars), because he has to
regulate the pressure on all 4 wheels. The breaking balance doesn't help you
anything because the weight balance changes all the time (passengers, amount
of gas). So a skilled driver may be able to be nearer to the optimal
pressure on one wheel. But ABS gets you nearly the optimum for all four
wheels. And no driver is able to stop his car fast when the road on one
side allows less traction then on the other (for example wet/icy spots on the
road).
By the way: ABS is well common in race too. The ITC (international touring
car series) uses ABS and is faster with ABS than without. ABS improved the
lap times by several percent. The european GP-series doesn't allow ABS
because they don't want the cars to become faster.
> In a corner your procedure will most likely induce a skid as the tire only has
> so much traction and one it's starts to skid it will most likely maintain it. ABS
> DOESN"T prevent the tires from skidding, it senses it and relieves brake pressure to
> stop it briefly. Its best to brake hard before you reach the corner in the first place
> and then ease completely off the brakes through the corner. If you are alread in a curve
> and must brake then you must feel for the balance in the car as you depress the pedal.
> Transfer too much weight to the fronts and the rear end will come around ABS or not.
> Generally speaking if the pedal starts to pulsate you've tractive limits for the rear
> and need to back off.
All drivers need ABS when driving too fast in a corner or
if they wants to avoid a crash. You can break in a corner without
loosing control of the car. Of course this is not possible if
you are near to the limit. If you have to break under this
circumstances, nothing can safe you from leaving the road.
So ABS doesn't improve your cornering-speed on a track.
> Join in with your local autocross group and try this and you will find this to be true.
>
> Carl Porter
> '87 Firebird & '92 Camaro
> G-stock competitor SCCA Solo II/ Solo Trials
> There are some new systems being developed which will change this. Instead of pulsing,
> the new systems apply back pressure to the pedal forcing you to back off. When these
> become available then you can stand on the pedal.
You always can stand on the pedal when using ABS. There is
no need from pushing you back from the pedal. ABS breaks as
best as possible (except snow). Where did you get this
information?
Peter Zangl
zn...@msg.ti.com
Willem-Jan Markerink
>In article <31FE6E...@ccwf.cc.utexas.edu>,
> Bruce Bostwick <li...@ccwf.cc.utexas.edu> wrote:
>>Willem-Jan Markerink wrote:
>>> Don't talk BS. What if someone wanders into you from the other lane?
>>> You can't predict everything.
>>
>>effort to maintain good situational awareness and keep yourself in a
position
>>where you have plenty of options *in case* someone wanders into you from
the
>>other lane.
So we agree you can't predict *everything*?
That was my point....;-))
If you want to predict everything you should definately stay in 1st gear.
>>> Suppose it is a bright sunny day, and someone wanders into you coming
from
>>> the other direction? And suppose your safest route is braking halfway on
>road
>>> and in the ditch? Then be very glad to have ABS.
>>
>>No, I'd probably use the road surface to get rid of as much speed as
possible
>>(which could be quite a bit!) and then take my chances in the ditch.
And if the only way to avoid the oncoming car is moving halfway in the ditch,
and there is no way to get back on the road, *and* there are trees in front
of you? How on earth are you going to perform treshold braking in that
situation?
Grass
>can
>>slow you down pretty quick if you're careful. ;-) I'd rather not have ABS
>>getting in the way of my threshold braking while I have good road to slow
>down
>>on, and I'd rather not have it getting confused when it hits the dirt and
>grass
>>with highly variable traction coefficients. After all, it can't *see*
where
>the
>>slick spots are; I can.
Several tests have shown that uneven traction coefficients are a perfect
condition to show ABS effectiveness. Once you get there, you be glad to have
ABS. You don't always have the choice between pavement and the ditch....
Speed Freak
lpa...@curly.cc.emory.edu (Lloyd R. Parker) writes:
>My point exactly. With ABS, any driver can stop like a pro, every time.
>It takes real skill and perfectly balanced brakes to duplicate this
>manually. And in a panic stop, who knows how they would react?
>Threshhold braking is nice, but can you say for certain you would do it
>in a panic stop with, say, a jack-knifed semi across the road as you
>round a curve?
'Any driver' might be able to pull up like a pro with ABS, but you've still
got to judge the correct point to start braking!
Also, if you stamp hard on your ABS as you round a curve with a jack-knifed
semi across the road you will probably lose control due to a spin. ABS
doesn't let you brake at full power while turning.
Ian
--
"We have no power to prevent ourselves being born; but we can rectify this
error - for it is sometimes an error." -- Friedrich Nietzsche
Ian Crocker i...@btcase.bt.co.uk
Lloyd R. Parker
Brandon Sommerville (bra...@caseware.com) wrote:
:
: Alot of cars actually have shorter stopping distances with no ABS. I
: am not arguing that these are under ideal circumstances with dry roads
: and no gravel, but it is possible.
That's simply not true. As I said, C/D (professional test drivers)
regulaly criticize cars w/o ABS for taking longer to stop. Please cite
some data showing this. Only on a surface like gravel or powdery snow or
sand, where building up a mound in front of the sliding wheel helps stop,
would mo ABS give shorter stopping distances.
Peter Zangl
Carl Porter wrote:
>
> > You always can stand on the pedal when using ABS. There is
> > no need from pushing you back from the pedal. ABS breaks as
> > best as possible (except snow). Where did you get this
> > information?
> >
>
> The articles I've read are from Motor Trend, Car & Driver, and so on. It's been a
> couple of years since I've seen an article on current systems. Driving techniques come
> from autocrossing and my understanding of how the system works. Neither of my cars have
> ABS. The ABS systems I've read about control two tires at a time, usually cross corner
> like lf/rr-rf/lr and were dumping system pressure 8 to 10 times per second. If the new
> systems are using an orifice or something to graduate the pressure on the tires then the
> driving techniques change and standing on the pedal might be more acceptable. Still cars
> from the factory are setup to lockup the front wheels first in most situations (has
> this changed?) and if the ABS system is pulsing continuously then to achieve maximum
> braking effect it would be better to back off the pedal pressure slightly. At least one
> wheel is locking up part of the time or the ABS wouldn't be pulsing and maximum braking
> and maximum control usually happens when all tires are not skidding.
>
> Carl Porter
The last article I read says that modern ABS does release
the pressure "slow" until the wheel rolls with suggested
speed. Also a newer ABS controls all four wheels (or at
least the front wheels) seperately. So when standing on the
brake, all wheels come close to maximum traction. Additionaly,
the ABS doesn't wait until the wheel blokades. It reactes in
the moment when the wheel rotates a dedicated amount slower
than estimated. So the traction doesn't decrease to the level
of full lockup.
As far as I know, all brake systems are designed to lockup
the front wheels first. The reason may be the danger of sudden
oversteer when the rear wheels would block sooner than the
front wheels. I can't prove this, though. I usualy don't
break full with cars I don't own (and, if possible, neither
with the cars I own too). =:-)
Greetings from Bavaria,
Peter Zangl
zn...@msg.ti.com
Lloyd R. Parker
Speed Freak (i...@btcase.bt.co.uk) wrote:
: lpa...@curly.cc.emory.edu (Lloyd R. Parker) writes:
:
: Also, if you stamp hard on your ABS as you round a curve with a jack-knifed
: semi across the road you will probably lose control due to a spin. ABS
: doesn't let you brake at full power while turning.
Huh? That's EXACTLY what ABS lets you do -- brake at full power while
turning! Stomp on the brakes and you can still steer.
Lloyd R. Parker
Carl Porter (3C...@MSG.TI.COM) wrote:
: What you seem to not realise here is that when the tires are rotating and the ABS
: is energized (pulsing) you have no brakes. The system releases pressure several times
: per second to allow the tires to rotate and generate slip angles for steering control.
: The other part of the time the pressure is on the brakes and the tires are skidding. if
: they weren't the system wouldn't be pulsing.
:
: Carl Porter
Wrong. ABS does not completely release the brake on the wheel; it backs
if off until the wheel rotates again, then reapplies full pressure. And
it does each wheel individually. So you DO have brakes, all the time.
Eric Bin
lpa...@curly.cc.emory.edu (Lloyd R. Parker) writes:
>Speed Freak (i...@btcase.bt.co.uk) wrote:
>: lpa...@curly.cc.emory.edu (Lloyd R. Parker) writes:
>:
>: Also, if you stamp hard on your ABS as you round a curve with a jack-knifed
>: semi across the road you will probably lose control due to a spin. ABS
>: doesn't let you brake at full power while turning.
>Huh? That's EXACTLY what ABS lets you do -- brake at full power while
>turning! Stomp on the brakes and you can still steer.
That's only half correct Lloyd. ABS allows you steer but while braking
hard but it doesn't mean you can do both very hard at the same time.
While turning, ABS cannot allow you the maximum braking power because of
the limits of traction provided by the tires. That's why they teach
people to be smooth with inputs. It allows a larger safety margin and
better traction in the above situation.
Eric
eb...@sfu.ca
Bruce Bostwick
Willem-Jan Markerink wrote:
> So we agree you can't predict *everything*?
> That was my point....;-))
> If you want to predict everything you should definately stay in 1st gear.
And you missed my point, which was that skilled driving is not just about what you
do with the situation *now*, but also what you do to give yourself multiple
options *later*. It's not necessarily about prediction, more about planning and
pilotage.
> And if the only way to avoid the oncoming car is moving halfway in the ditch,
> and there is no way to get back on the road, *and* there are trees in front
> of you? How on earth are you going to perform treshold braking in that
> situation?
Quite honestly, I wouldn't *be* in that situation. The blind curve is an open
invitation to think "gee, if someone came around that corner right about now, I'd
be up the proverbial creek, wouldn't I?" and maybe get rid of some speed before I
reached it. It's always possible to come up with nightmarish "what ifs" in which
nothing you can do will get you out of a collision .. I'm not going to go into all
of them here.
> Several tests have shown that uneven traction coefficients are a perfect
> condition to show ABS effectiveness. Once you get there, you be glad to have
> ABS. You don't always have the choice between pavement and the ditch....
But you always have a choice -- I've been driving for 15 years and have never been
in a situation that didn't have *some* way out of it. There's always something
more you can do. In a near-collision situation, I stay with the controls until
everything comes to a stop, and I'm always looking for a place to duck into just
in case. Predicting, maybe not. Staying aware and planning ahead, definitely.
I'm not sure how ABS can help me there.
--
<BGB> http://ccwf.cc.utexas.edu/~lihan/ mailto:li...@ccwf.cc.utexas.edu
Henri R Helanto
Aardwolf <se1...@itis.com> writes:
>Exactly--perhaps in some residential areas they may be too FAST?
>I think the other main factor you forgot about is the road itself.
Um, perhaps I took the 'road permitting' -thing for granted.
>Try doing 100+ in some of the switchbacks going up into the Black
>Hills---hell try doing over 40 in most cars--and you'll most likely be
>thrown off the road and end up a couple hundred feet below where you
>wanted to be, smashed to bits at the bottom of a rock-covered slope.
Of course, I should've added 'compared to how fast you could
drive there if there were nobody else around'. On track you
could drive as fast as your car would go if there weren't any
turns ;)
Leroy Curtis
In article <4tp922$3...@morgoth.sfu.ca>, Eric Bin <eb...@sfu.ca> writes
at about 2 mph, which is not really practical when driving along a busy
main road, which may have a posted limit of 40 or 50 mph, ABS must
increase your chances of avoiding an accident. Of course you back off if
you see a car waiting to turn out of a side road, just in case the
person driving it has forgotten their glasses that day or something, but
usually these people lull you into a false sense of security by waiting
until you are very close to them before moving out into your path.
Regards
--
Leroy Curtis
Carl Porter
Carl Porter
> In snow, I agree with you because you can lock the wheels and build
> little piles of snow in front of the tires thus increasing your
> friction. On most conditions (dry, wet, ice) you want static friction
> which is only possible when the tires are rotating.
Willem-Jan Markerink
In article <ant29054...@sparkg.wave.co.nz>,
Greg Spark <spa...@wave.co.nz> wrote:
>Situations where the ABS comes into action in normal driving are very rare
if
>you are driving safely (twice in 5 years in my experience). Therefore I
>recommend practicing using it on a bit of deserted road now and again.
I disagree slightly. I find ABS a perfect solution to assess road traction
without skidding everywhere. This way I know where my limits are, and keep on
the safe side. Not as easy with normal brakes.
But your point on stomping on the brakes is a good one!
Bentley
Lloyd R. Parker (lpa...@curly.cc.emory.edu) wrote:
: That's simply not true. As I said, C/D (professional test drivers)
: some data showing this. Only on a surface like gravel or powdery snow or
: sand, where building up a mound in front of the sliding wheel helps stop,
: would mo ABS give shorter stopping distances.
....except in the Viper, right? It's the ONE car that doesn't ABS?
Keith M. Ryan
In a previous article, "d.jensen"@geel.dwt.csiro.au (Dennis Jensen) says:
>
>What a brilliant driver you must be; those F1 drivers must be absolutely
>terrible, after all, prior to being banned, F1s used ABS. You, I guess, would
>have had the team remove ABS so that it didn't interfere with your threshold
>braking. Maybe you should have instructed Ayrton Senna, Alain Prost and the
>like on threshold braking technique:)
>
>In all seriousness, you obviously don't know much about ABS. ABS only operates
>when the wheel has started to lock up, in other words, you have gone beyond
>threshold braking, and the ABS has to unlock the locked wheel. With ABS, if
>you are perfect with your threshold braking, the ABS will never activate, and
>you will just have "normal" brakes.
>
>I reiterate, ABS is for when you have stuffed up your threshold braking, it
>won't interfere if your threshold braking has not caused lock up.
Hey Dennis, do you really think the ABS systems that the F!
used to use were the same one that GM puts on their cheapest cars?
What's that? They're different? I do not understand.. I thought all
ABS systems operated the same way, ... Well, when using the F1
argeument, that is *EXACTLY* what you are implying..
I think if you drove what GM and others think "ABS" systems
are on your average priced car is, you'll think again about them. When
I used to live in Buffalo, I did *ALOT* better in my non ABS equipted
Talon, than many other people wiht ABS systems..
Willem-Jan Markerink
In article <4tsvre$2...@zeus.orl.mmc.com>,
rgil...@unconfigured.xvnews.domain (Bob Gilbert) wrote:
>The biggest problem with ABS (besides cost and complexity) is that there
>does exist some circumstances where ABS is detrimental. When stopping in
>soft snow, sand, or gravel it is frequently desired to allow locking of
>the brakes to improve stopping capability since a wedge of material will
>be plowed up by the locked tires to assist in stopping. There are several
>other similar (although somewhat rare) cases.
But you still can't steer in those circumstances at full lock. Such roads are
likely to be uneven and off-camber, so they might take you in very unwanted
directions....
And FWIW: some 4x4's switch off ABS in 4low (MB, TLC). Some serious
offroaders also mount a switch on the dash to switch off in any situation.
Aardwolf
Henri R Helanto wrote:
> Um, perhaps I took the 'road permitting' -thing for granted.
'Sokay. Most of us tend to do that as well ;-)
> Of course, I should've added 'compared to how fast you could
> drive there if there were nobody else around'.
Yep, I guess that's kind of a given. But you did sorta say that with
reguard to traaffic conditions. (As an example, on the Beltline
highway here almost everyone does 65-70, the limit is 55, the police
don't even look sideways at you unless you're going over 65, more
usually over 70. They oughta just raise the limit to 65--it'd improve
traffic flow. And during rush hour traffic frequently slows to a
crawl or complete stop, hence regulating itself---under those
conditions it is virtually physically IMPOSSIBLE to go faster than the
rest of traffic.)
>On track you could drive as fast as your car would go if there weren't any
> turns ;)
Isn't that pretty much drag racing? ;-)
Aardwolf.
Aardwolf
So what kind of ABS system does the 1994 Caprice 9C1 use? It isn't
exactly a "cheap" car but it's by no means an "expensive" one either.
Aardwolf.
Aardwolf
Bob Gilbert wrote:
> One of my biggest concerns is that manufacturers will rely on ABS to band-aid
> inherently imbalanced brake systems, offering substandard braking should the
> ABS be disabled for any reason (fault detected, etc.).
At least, whatever the effectiveness of the ABS system installed in
that particular type of car, substandard braking with ABS disabled is
NOT something you have to worry about in an ABS equipped cop car.
Aardwolf.
Aardwolf
Bob Gilbert wrote:
> There are also some cases where driving over large bumps or sudden hill
> crests where the car might become briefly airborne may fool the ABS into
> thinking the car has actually completed the stop while airborne
> (effectively disabling the ABS) allowing the wheels to remain locked
> when the car lands, or cause the ABS to detect the momentary locking
> while airborne and remove the braking pressure to a point greater than
> desired requiring an extended time (thus a loss of braking) to re-build
> brake pressure back to its desired level. The above scenario was discovered
> by the Corvette Challenge racers at a circuit where a hill was crested,
> causing momentary flight, at the beginning of a normal braking zone. In
> that case the drivers claimed that they would prefer to not have the ABS,
> but that was the only circumstance they encountered where they felt that
> way.
So why not include a vertical accelerometer and/or suspension load
sensors with the ABS system? And a "snow/gravel" mode?
Aardwolf.
Bob Gilbert
In article <4tqjmb$r...@curly.cc.emory.edu>, lpa...@curly.cc.emory.edu (Lloyd R. Parker) writes:
> Brandon Sommerville (bra...@caseware.com) wrote:
> :
> : Alot of cars actually have shorter stopping distances with no ABS. I
> : am not arguing that these are under ideal circumstances with dry roads
> : and no gravel, but it is possible.
>
> regulaly criticize cars w/o ABS for taking longer to stop.
I'd say the only part of what Brandon said that is questionable is the
"alot of cars" part. There are some cars that have pretty well balanced
brakes w/o ABS, and some of these models may not have been offered with
the best ABS. Not all ABS are the same. There certainly have been
some tests conducted where a good driver driving a car with a well
balanced braking system on a consistent surface was able to consistently
stop in a shorter distance with the ABS disabled over that when the ABS
was enabled. But the difference was pretty small (like maybe only a foot
or two), certainly required the drivers full attention, and was conducted
under idea conditions.
> Please cite some data showing this.
I might be able to dig through the reference materials and scarf some up,
but don't hold your breath.
> Only on a surface like gravel or powdery snow or
> sand, where building up a mound in front of the sliding wheel helps stop,
> would mo ABS give shorter stopping distances.
True, but I wouldn't say "only", there are other cases to consider.
Wet leaves over pavement where locking causes the tires to grind
through the leaves to make contact with the pavement is another case.
There are also some cases where driving over large bumps or sudden hill
crests where the car might become briefly airborne may fool the ABS into
thinking the car has actually completed the stop while airborne
(effectively disabling the ABS) allowing the wheels to remain locked
when the car lands, or cause the ABS to detect the momentary locking
while airborne and remove the braking pressure to a point greater than
desired requiring an extended time (thus a loss of braking) to re-build
brake pressure back to its desired level. The above scenario was discovered
by the Corvette Challenge racers at a circuit where a hill was crested,
causing momentary flight, at the beginning of a normal braking zone. In
that case the drivers claimed that they would prefer to not have the ABS,
but that was the only circumstance they encountered where they felt that
way. I'm sure there exist other unusual circumstances where ABS can be
detrimental to braking distances.
-Bob
Bob Gilbert
In article <4tnsgl$d...@curly.cc.emory.edu>, lpa...@curly.cc.emory.edu (Lloyd R. Parker) writes:
> Carl Porter (3C...@MSG.TI.COM) wrote:
> :
> : It's the driver that makes the difference with or without ABS. Most drivers
> : don't have the experience or skill necessary to apply the brakes at the max available
> : without locking up. Some can, in their case the current batch of ABS systems causes
> : them to need more room to stop if they use it. This is because they release pressure
> : on the brakes several times a second. No pressure no brakes, several times a second
> : and it takes longer to stop.
>
> Not so. ABS doesn't totally release the pressure, it just backs off to
> eliminate lock-up.
Actually, most ABS does release and re-apply the braking pressure, but it
is done at a frequency that exceeds the mechanical/hydrolic response of the
brakes, thus allowing a psuedo threshold modulation to be acheived by varying
the duty cycle of the commanded release of pressure.
> Threshhold braking is only useful if your brakes are perfectly balanced
> and you can hold ALL 4 at that point. Generally, you can't --
Threshold braking is still useful even with a less than perfectly balanced
system, you just have to determine which wheel you will use to determine
the threshold. You may decide (or not) to ignore a prematurely locking wheel
if you feel that you still have a lot more braking available from the other
wheels. Of course, you might want to attempt to modulate the locked wheel
to allow yourself to take some evasive action without loosing control (i.e.
unlock the wheel to allow it to provide some cornering capability). Lots
of quick decisions (stop faster, or sacrifice some braking to take evasive
action?) to be made, and something that needs to be experienced a few times
before one can become good at it. Good reason to compete in autocrosses
or attend performance driving schools.
> you'd need 4 brake pedals, one for each wheel, to do that.
Absolutely. Probably the biggest advantage of ABS (when taken, as many
systems treat both rear wheels as one) is the ability to modulate each
wheel individually and independently.
> Read some articles in C/D for example -- these are professional testers,
> and they pan non-ABS systems for taking LONGER to stop.
The distances to stop under consistent conditions is not very great (ABS
vs no-ABS), but certainly under varying conditions, especially when the
conditions vary for each wheel, ABS provides a substaintial improvement
in stopping distances.
The biggest problem with ABS (besides cost and complexity) is that there
does exist some circumstances where ABS is detrimental. When stopping in
soft snow, sand, or gravel it is frequently desired to allow locking of
the brakes to improve stopping capability since a wedge of material will
be plowed up by the locked tires to assist in stopping. There are several
other similar (although somewhat rare) cases.
One of my biggest concerns is that manufacturers will rely on ABS to band-aid
inherently imbalanced brake systems, offering substandard braking should the
ABS be disabled for any reason (fault detected, etc.).
-Bob
Bruce Simpson
"Timothy P. Banse" <middl...@avalon.net> wrote:
>ABS does reduces stopping distance. But its primary purpose is to allow
>the driver to steer during hard braking. In other words, because the
>wheels don't lock up, you don't lose control of the car.
One has to wonder about this in a modern lightweight FWD car though...
Under heavy braking there's an awful lot of weight transfer going on there
with some rather dire consequenses likely to occur with respect to
handling.
Try this for instance... drive your FWD car on a large flat (safe) surface
in a circle until you're nearing the limits of adhesion at about 50mph.
Now take your foot off the gas and watch what happens to the tail of your
car... chances are it will come right out and you may even spin 180 degrees
or more. It's simple to understand why... power off - weight transfer to
the front - front wheels are braking, rear wheels have next to no grip
because they have no weight pushing them to the road-surface - result
equals spin.
Does this happen if you hit the brakes real hard (ABS) then turn the wheel
sharply??? I don't know but I fail to see why it wouldn't. Given that
most people are semi-paniced in such circumstances, I doubt that
"controlled" steering inputs could be expected from drivers and wonder if
ABS cars still hit things - but side or rear on instead of front-on.
Can someone clarify?
--------------------------------------------------------------
Aardvark - an weekly net-magazine taking a look at the
internet in NZ and around the world.
http://www.voyager.co.nz/~bsimpson/aardvark.htm
JBlessing
In article <4tnns2$o...@bcarh8ab.bnr.ca>, alp...@bcarh311.bnr.ca says...
>>No, I'd probably use the road surface to get rid of as much speed as
possi
>ble
>>(which could be quite a bit!) and then take my chances in the ditch.
Gras
>s can
>>slow you down pretty quick if you're careful. ;-) I'd rather not have
AB
>S
>>getting in the way of my threshold braking while I have good road to
slow
>down
>>on, and I'd rather not have it getting confused when it hits the dirt
and
>grass
>>with highly variable traction coefficients. After all, it can't *see*
whe
>re the
>>slick spots are; I can.
>
> I watched a car show (AUTOMAG PLUS) where a professional driver
>tested his skills on a 240SX (I think) with and without ABS enabled.
>The tests included collision avoidance on a wet surface and emergency
>braking where you have to move partly off the road.
>
> Using the threshold braking technique he was unable to make the
>maneuvers. They also showed how much worse it was to just lock the
>wheels.
>
>In the first collision avoidance tests...
>As you turn and the car's weight shifts the tires get different amounts
of
>traction (not to mention the fact that a wet surface isn't going to have
a
>homogeneous traction coeffiecient anyways). This is where ABS shines
becau
>se
>it brakes the wheels individually. Threshold braking cannot do this.
>
>In the second test where he tried to stop half on the road...
>Well ABS shines here too because the wheels on the pavement have great
>traction compared to the wheels in the gravel or grass. If he threshold
>braked to the point just before the wheels with poor traction locked
>then he took much much longer to stop. Braking beyond that point caused
>the off road wheels to lock and drag the car off the road.
>
>As for getting confused, well these systems can process wheel conditions
>much faster than any human can but of course, its the human who should
>usually be able to avoid getting into these conditions.
--
Amen. Anyone that thinks they can outbrake a good 4WAL system on differing
surfaces is just fooling themselves. A good system measures each wheels
deceleration and corrects it many times a second. Threshold braking can't
come close. Have a good ABS system and know how to use it.
Jordan Blessing L1 Master Tech
horde of barbarians
>Amen. Anyone that thinks they can outbrake a good 4WAL system on differing
>surfaces is just fooling themselves. A good system measures each wheels
>deceleration and corrects it many times a second. Threshold braking can't
>come close. Have a good ABS system and know how to use it.
OK. Now which ABS's are good?
Serge
E. Honda
Bentley <ben...@access2.digex.net> wrote in article
<4tglmg$i...@news3.digex.net>...
> Kai (kai...@ix.netcom.com) wrote:
> : Anyway, not all insurance companies have stopped offering discounts.
Shop
> : around if this affects you.
>
> Rumor has it that the ABS does in fact help avoid accidents, but after
one
> occurs, there are few -- if any -- telltale skid marks. Thus, much harder
> to prove who is liable. Thus, the insurance companies quickly soured on
> ABS.
Not a problem in states with No-Fault. We just pay big premiums all the
time, and the insurance companies are happy. :)
My Integra LS has ABS and four wheel disc brakes.
I like the braking, it's very nice, very smooth, and most of the time I
feel like I'm stopping pretty quick.
As far as ABS. Haven't really had to use it. I'm good enough to stop
before I have to, I guess.
It did engage in the winter on ice, didn't help any. It also engaged in
the snow, and actually in my opinion made things worse. I'm usually pretty
confident moving around in snow at 10 mph, and locking the wheels at the
right time can be beneficial.
Kenneth Hayes
> >somebody wrote:
> >ABS does reduces stopping distance. But its primary purpose is to allow
> >the driver to steer during hard braking. In other words, because the
> >wheels don't lock up, you don't lose control of the car.
standard braking systems is much less than with ABS. There is a FAQ
at ftp://ftp.balltown.cma.com/pub/misc/Autos/consumer-questions.text
JBlessing
In article <4u05r0$7...@panix2.panix.com>, ll...@panix.com says...
--
Basically you want a real 4 wheel ABS system, with 4 circuits, not 3. Some
tie the rear wheels together as a single circuit. Some vehicles only have
rear wheel ABS, (mainly pickups) and this will not give you steering
control, they just help prevent the rear end from coming around.
Willem-Jan Markerink
In article <MURALIDH.7...@servms.fiu.edu>,
MURA...@servms.fiu.edu (Vitalstatistix) wrote:
>Just out of curiosity, would ABS have helped me in the following situation:
>
>I was going about 40 mph when a old lady in front of me decided to make an
>abrupt right turn without warning. I was not tail gating, but perhaps
>following more closely than I should have. Hit the brakes and the car
simply
>would not stop. I had time to pump the brake several times and nothing
>happened. Ended up bumping the lady in front causing minor damage to her
rear
>bumper and tail lights. Unfortunately for me, the driver behind me had the
>same problem and ended up rear ending me (causing the demise of my beloved
89
>CRX Si). When we got down from the car, we noticed that the right side of
>the road was "caked" with concrete/asphalt and quite different from the left
>side. Would ABS help under these conditions?
>
>Krish
It would at least have kept your car going straight....if the slick stuff is
on the right, you otherwise are catapulled into the other lane, because the
car pivots around the grabby brake side.
And you would have been able to steer on the final moment, perhaps choosing
the ditch at slow speed.
Keith M. Ryan
In a previous article, hhel...@cc.hut.fi (Henri R Helanto) says:
>
>>The posted speed limit is for dry full visibility conditions. It
>>was raining, maybe you should have been going slower than 25?
>
> Posted speed limits are the legislator's idea of how fast any
> driver can drive in any kind of a car in average visibility
> and weather conditions, let's not forget that. Personally, I
I see from your account, that you are in Finland.
You just have to understand, that here in the US, safety
or vehicle dynamics have not been a factor in deciding speed limits for over
25 years. There were no honest research in this for the 55mph national
limit, then the 60 and then 65.. However, there *WAS* alot of lobbying
by finantually vested parties, e.g. insurance, police officers, etc.
The speed limit was set more to maximize revenue, than for safety.
Dennis Jensen
In article <4tlbs1$9...@bcarh8ab.bnr.ca>, pro...@nortel.ca wrote:
>
>In article <4tl95e$2...@curly.cc.emory.edu>, lpa...@curly.cc.emory.edu (Lloyd
R. Parker) writes:
>|> Brandon Sommerville (bra...@caseware.com) wrote:
>|> : For pure braking ability, four disks are better than disk/drum setups.
>|> : A skilled driver can beat ABS every time with threshhold braking, but
>|> : this is much harder to do in the wet or in other adverse conditions.
>|>
>|> Not necessarily. A driver, skilled or otherwise, can NOT hold each wheel
>|> to the threshhold unless the brakes are perfectly balanced. ABS varies
>|> EACH wheel (or maybe the rears as one); a driver cannot do that without 4
>|> brake pedals. They banned ABS in F1 because it was too effective -- and
>|> those are professional drivers.
>
>Four-time F1 world champion, the Professor, Alain Prost, didn't like ABS
>on his '93 Williams. Perhaps he can easily out-perform ABS? BTW, the reason
>F1 banned ABS (and other goodies such as active suspension which changes
>ride height automatically, and traction control) was because machines and
>computers were doing much of the driving instead of the driver.
>
But then he did not like active suspension either. So what is the point. He
didn't like electronic aids in 1993 as he was a year behind on the learning
curve, that is all. Additionally, amny drivers preferred the actual
competition of finding their own limits, as opposed to having electronically
controlled limits, where the limits are the same. This does not mean to say
that the electronic limits are not higher-they are.
Dennis
Dennis Jensen
In article <31FE5A...@ccwf.cc.utexas.edu>,
Bruce Bostwick <li...@ccwf.cc.utexas.edu> wrote:
>Dennis Jensen wrote:
>> This is absolute hogwash. In order to lock brakes, all that you need is for
>> the torque applied to the wheel by the brake to be larger than the torque
that
>> the tyre will allow the wheel to absorb through friction.
>
>And if the brakes are perfectly balanced, the force required to break the
tires
>loose is *very* large -- the reason the car skids when the brake forces
aren't
>balanced is that the skidding tire transfers its traction load to the other
>three, which usually let go more because of the sudden increase that because
of
>the total force applied. There are dynamic factors at work here as well,
>remember.
>
>> The brake proportioning valve has nothing to do with the maximum braking
that
>> can be applied, it only proportions the braking power between front and
rear;
>> it does not change the total force. If you were unable to lock up your
wheels
>> with "both -feet-on-the-pedal", then I suggest that you get your brakes
seen
>> to, you have a problem.
>
>I neglected to mention in my previous post that in the panic stop, everything
in
>the car went flying and a window nearly got broken. It was an *extremely*
sudden
>stop, and subjected all of the occupants of the car to such force that
without
>seat belts none of them would have been able to stay in the seats. And in
all
>that, none of the tires so much as squeaked. Like I said, though, the brake
>system was of very good quality and in excellent adjustment, and the tires
were
>A-traction Michelins. Lesser equipment might well have broken loose.
And more equipment than you have often breaks loose. Ever seen F1 and Indycars
lock up, sometimes all four wheels? And these things brake at 4G's, not the
puny 1.2G's at best in road cars.
>
>My point is that ABS is of questionable value, because all it really is is a
way
>to substitute technology for craft. It does not particularly enhance the
>abilities of a skilled driver, and the high-tech gadgetry is more prone to
>failure just when you need it most.
Remember, ABS does not acrivate unless you go over the limit. In other words,
you have stuffed it up.
Dennis
Remember Murphy's Law? Brakes are one of
>his specialties. ;-)
>
Richard Jozefowski
In article <4u0nh3$j...@zeus.intellinet.com>, Kenneth Hayes
<mailto:dera...@sea.ar.ispnet.com> wrote:
> For an experienced driver on dry pavement, stopping distance from
> standard braking systems is much less than with ABS.
An experienced driver on dry pavement shouldn't get themselves into a
position where they have to brake so hard that they may skid or activate
ABS, at least not on a public road. In 20 years of driving I can't recall
it happening to me, but then I know I'm no Damon Hill and drive accordingly.
--
Richard.
Lloyd R. Parker
Kenneth Hayes (dera...@sea.ar.ispnet.com) wrote:
: > >ABS does reduces stopping distance. But its primary purpose is to allow
: > >the driver to steer during hard braking. In other words, because the
: > >wheels don't lock up, you don't lose control of the car.
: For an experienced driver on dry pavement, stopping distance from
: standard braking systems is much less than with ABS. There is a FAQ
: at ftp://ftp.balltown.cma.com/pub/misc/Autos/consumer-questions.text
:
Sorry, that is just not so. A driver, no matter how experienced, cannot
hold all 4 wheels at the threshhold unless the brakes are perfectly
balanced. ABS can do this. C/D regularly criticizes cars w/o ABS for
having longer stopping distances, and they are experienced drivers.
Besides, who knows how they're going to react in an emergency?
Also, remember, faqs are written by people, not God.
Bob Gilbert
In article <4tu1jd$a...@news.express.co.nz>, br...@faxmail.co.nz (Bruce Simpson) writes:
>
> One has to wonder about this in a modern lightweight FWD car though...
>
> Under heavy braking there's an awful lot of weight transfer going on there
> with some rather dire consequenses likely to occur with respect to
> handling.
True, regardless of FWD or not however.
> Try this for instance... drive your FWD car on a large flat (safe) surface
> in a circle until you're nearing the limits of adhesion at about 50mph.
> Now take your foot off the gas and watch what happens to the tail of your
> car... chances are it will come right out and you may even spin 180 degrees
> or more. It's simple to understand why... power off - weight transfer to
> the front - front wheels are braking, rear wheels have next to no grip
> because they have no weight pushing them to the road-surface - result
> equals spin.
It's called "trailing throttle oversteer", and can occur in many cars, not
just FWD (in fact, tends to be less obvious in most FWD cars as they tend
to substantial understeer).
> Does this happen if you hit the brakes real hard (ABS) then turn the wheel
> sharply???
Absolutely! Even better if you start turning first, then slam the brakes
(ABS or otherwise).
> I don't know but I fail to see why it wouldn't. Given that
> most people are semi-paniced in such circumstances, I doubt that
> "controlled" steering inputs could be expected from drivers and wonder if
> ABS cars still hit things - but side or rear on instead of front-on.
>
> Can someone clarify?
I tried, but you got it mostly right. The problem lessens somewhat when
the conditions are poor and braking (ABS or not) is reduced resulting in
less load transfer.
-Bob
Abe Getchell
I must throw my thoughts and a little experience that happened
to me this weekend into this thread to shead some light on the subject.
One of my friends and I were out driving some country roads when we hit
my favorite stop in Lexington, Ky. The end of Tates Creek road where it
traverses down to the Kentucky River. There are about 10 *sharp* turns
that take you all the way down to the bottom. It is a good high-rpm
second gear run. Well, we had gone down it once and come back up (I
always go faster on the way up. For some reason I'd rather hit a
rockface then fall off of one!) once with no problems and were having
a good time. We let the car cool off (oil temp was 252F!) for a bit as
we rested and took a look at the beautiful country side. We headed back
down to do one more run. The way down was fine. No traffic, dry,
everything went great. On the way back up, right at the top there is
this
nice little decreasing radius turn that I forgot about. I went in a
little
to hot and kept on the throttle. Since the car is VERY nicely balanced
now
with the big front and rear swaybars, the car started sliding perfectly
sideways towards the rock face. I pressed hard on the brakes and the
ABS
kicked in right away letting me take control of the car while I was
*very*
rapidly slowing down. I pulled it back in and continued up the
mountain...
If it had not been for the ABS I *would* have hit the rockface as a
result
of my own driving error and the brakes locking up under hard
deceleration.
I probably would be writing this from a hospital bed, so I am glad for
my
ABS system. It definately saved me from injury/death!
Abe
'96 Arrest-Me-Red GTI-VR6
--
----------------------------------
Abe L. Getchell
Systems Programmer
Sanders-Brown Center on Aging
University of Kentucky
Lexington, Ky 40536
(606)323-6040
E-Mail: sys...@iguana.coa.uky.edu
pan...@iglou.com
http://www.coa.uky.edu/~sysabe/
Fahren Auf Der Autobahn!
----------------------------------
Bob Gilbert
In article <4u0nh3$j...@zeus.intellinet.com>, Kenneth Hayes <dera...@sea.ar.ispnet.com> writes:
> > >somebody wrote:
>
> > >ABS does reduces stopping distance. But its primary purpose is to allow
> > >the driver to steer during hard braking. In other words, because the
> > >wheels don't lock up, you don't lose control of the car.
>
> For an experienced driver on dry pavement, stopping distance from
> standard braking systems is much less than with ABS. There is a FAQ
a little
> at ftp://ftp.balltown.cma.com/pub/misc/Autos/consumer-questions.text
-Bob