GPL - real techie question about ramp angles and clutches
Wolfgang Preiss
ugly ASCII art. And it's pretty long, too.
I know this question has been talked about a lot, but I haven't yet
seen an answer that allows me to understand what those beast are and
how they work. And adjusting them without knowing how they work leads
to nothing and is driving me nuts. So: what the heck are those
clutches, where are they installed, and what do they do? Likewise for
the ramp angles.
Let me tell you how a standard differential gear looks like, and you
tell me where the clutches and ramp angles come into play. Deal? [I
don't have a proper dictionary for automotive terminology, and I know
the names of most parts only in German, so I have to paraphrase a bit
at times. Bear with me. Info about the proper English terminology is
appreciated.]
In the diff box, there is a huge gear that is driven by a smaller gear
on the end of the driveshaft. In the center of the huge gear, there is
a casing that contains four small conical gears. Two of those gears
are connected to the two axleshafts. The other two gears sit on a
separate pinion shaft.
The whole thing looks (roughly :) like this:
[Switch to Courier of another fixed pitch font, or it will look even
less comprehensible...]
|\
||XXXXX|XXXXXX
|| | X
|| \\zz|zz// X
|| 0 | 0 X
=================||==0 | 0==X===============
|| 0 | 0 X
|| //zz|zz\\ X
|| | X
||XXXXX|XXXXXX
|/
The bigger part on the left side is the big gear I wrote about.
The things made of "=" signs are the axleshafts.
The part made of "X"s is the casing.
"\zz|zz/" is one of the conical gears with a part of its pinion shaft.
"\
0
0
0
/" is one of the gears at the end of the axleshafts.
Now, where do the clutches come in? And to what do the ramp angles
refer?
Thanks for any insights!
--
Wolfgang Preiss \ E-mail copies of replies to this posting are welcome.
wo...@gmx.net \ Spam (UCE) is not welcome will lead to the cancellation
wo...@stud.uni-sb.de \ of your account. I mean it. Spammer, you have been warned.
5th Doctor
Wolfgang Preiss <wo...@gmx.net> wrote in message
news:37a17d2c...@news.rz.uni-sb.de...
> Warning: this posting contains a pretty technical question and some
> ugly ASCII art. And it's pretty long, too.
>
> I know this question has been talked about a lot, but I haven't yet
> seen an answer that allows me to understand what those beast are and
> how they work. And adjusting them without knowing how they work leads
> to nothing and is driving me nuts. So: what the heck are those
> clutches, where are they installed, and what do they do? Likewise for
> the ramp angles.
I'm not sure of the physical layout of a 60's era differential, but I
understand how it works.
Ramp Angles...
the two numbers for ramp angles, 85/30, correspond to power/coast values for
when the diff locks up. Higher values on the power side means quicker
lockup when you apply throttle, lower values on the power side means lazier
lockup when you apply throttle.
On the coast side, lower values means that when you lift off the throttle,
the diff is slow to lockup, higher values means the diff locks at the
slightest hint of throttle lift. (I find this undesireable)
example...15/85 values would mean you pretty much gotta floor the gas to get
the car to move, yet as soon as you begin to lift off the gas the diff would
begin to lockup and try to slow the car.
Clutches...
this sets how tightly the diff locks up between the rear tires. More
clutches means that the rear tires are allowed less ability to spin at
different rates (like when turning a corner). Less clutches allows for a
little more play between the tires. If you find that it's too hard to
control a powerslide or trailbraking, try less clutches.
Hope that helps
Andre Warringa
Thanks Doc!
Andre
Steve Blankenship
>I'm not sure of the physical layout of a 60's era differential, but I
>understand how it works.
<snip>
>Higher values on the power side means quicker
>lockup when you apply throttle, lower values on the power side means lazier
>lockup when you apply throttle.
Hmmmm. You might want to rethink that. :-)
See quote at bottom from:
http://simracing.com/alison/gpl/ferrari.htm
Where Alison Hine and Dave Kaemmer are discussing GPL diff. settings. Give the
article a peek if you haven't; it's food for thought, even if your car's not
red.
Cheers,
Steve B.
"Note that in a Salisbury-type differential such as those used by GPL's cars, a
higher ramp angle (e.g. 85 degrees) gives less locking, while a lower ramp
angle (e.g. 30 degrees) gives more locking. On the other hand, higher preload -
more clutches - gives more locking."
remove "edy" from address for email
Greg Cisko
>I'm not sure of the physical layout of a 60's era differential, but I
>understand how it works.
>the two numbers for ramp angles, 85/30, correspond to power/coast values
for
I hate to be an ahole, but this stuff was covered in the manual I
got with the game :-)
--
Header address intentionally scrambled to ward off the spamming hordes.
cisko [AT] ix [DOT] netcom [DOT] com
drb...@ibm.net
>clutches, where are they installed, and what do they do? Likewise for
>the ramp angles.
See Carroll Smith's book, "Drive to Win" for a complete
explanation with pictures. Much other useful stuff.
bob
5th Doctor
Greg Cisko <ci...@nOsPaMix.netcom.com> wrote in message
news:7nvnvt$2...@dfw-ixnews10.ix.netcom.com...
5th Doctor
lower the number on the power side, the more I gotta mash the gas to
accelerate. what gives?
Steve Blankenship <steve...@aol.comedy> wrote in message
news:19990731131713...@ng-ch1.aol.com...
> 5th Doctor tyna...@SPUNKinreach.com wrote:
>
>
> >I'm not sure of the physical layout of a 60's era differential, but I
> >understand how it works.
> >Higher values on the power side means quicker
Joel Willstein
5th Doctor wrote in message <1jDo3.83$T5....@news.inreach.com>...
>Ramp Angles...
>the two numbers for ramp angles, 85/30, correspond to power/coast values
for
>when the diff locks up. Higher values on the power side means quicker
>lockup when you apply throttle, lower values on the power side means lazier
>lockup when you apply throttle.
>On the coast side, lower values means that when you lift off the throttle,
>the diff is slow to lockup, higher values means the diff locks at the
>slightest hint of throttle lift. (I find this undesireable)
>example...15/85 values would mean you pretty much gotta floor the gas to
get
>the car to move, yet as soon as you begin to lift off the gas the diff
would
>begin to lockup and try to slow the car.
>Clutches...
>this sets how tightly the diff locks up between the rear tires. More
>clutches means that the rear tires are allowed less ability to spin at
>different rates (like when turning a corner). Less clutches allows for a
>little more play between the tires. If you find that it's too hard to
>control a powerslide or trailbraking, try less clutches.
>
>Hope that helps
Excellent explanation on what's going on with ramp angles and clutches.
But I still have a few questions. For starters,I drive a Lotus,(and a
Ferrari when I just can't seem to get the lotus to handle at all).
1- Almost every setup I've ever seen uses a ramp angle of 85/30. From your
explanation,I take this to mean that the rear locks up slower when applying
gas as well as locking up slowly when getting off the gas and on the brakes.
Or would one be better off using a lower power number?
2- The more clutches the tighter the rear. Yet most of the latest setups
have gone to 4 clutches rather than 2 for the Lotus and Ferrari. From your
explanation,I would think that 2 would be a better choice.
At the start of the race when I apply the gas (no matter how easy),the
car pulls violently to the left. I always get left behind. Once I'm
going,the steering is as it should be. This problem was never this bad until
I installed the patch and started using a MSFF wheel rather than my T2. Slow
corners that require 1st or 2nd gear usually wind up with violent oversteer
when I apply the power.
Joel Willstein
jaw...@sprynet.com
Wolfgang Preiss
>"Note that in a Salisbury-type differential such as those used by GPL's cars, a
>higher ramp angle (e.g. 85 degrees) gives less locking, while a lower ramp
>angle (e.g. 30 degrees) gives more locking. On the other hand, higher preload -
>more clutches - gives more locking."
I think I got it - with the help of two pages from Carroll Smith's
"Drive to Win", which someone kindly e-mailed me. Maybe some people
are interested in the technical principles - if not, press the "skip
message" button NOW. :) Everybody else, enjoy as much as possible. And
those of you who really know about this stuff, please don't hesitate
to correct me whenever I get something wrong.
A usual "open" diff, which we have in our normal road cars,
distributes the power to the wheels in such a way that - when going
through a curve - the inner wheel can rotate less frequently than the
outer wheel, which has to cover a greater distance.
This is a Good Thing, but it has a downside to it: as soon as one of
the wheels loses grip (f.i. the inner wheel in a curve), all the power
goes to this wheel. In an extreme case, we have one wheel spinning
madly, while the car stands still.
Using NO diff is not an option on road courses, since the car wouldn't
want to turn at all with such a setup. This leads to a lot of tire
wear and a very ugly behavior in tight turns. Yet, the car would
accelerate very nicely in a straight line. Champ Cars on large ovals
do without a diff and use "stagger" (rear wheels of different sizes, a
larger one on the outside) to facilitate turning.
What we want is a diff that allows us to accelerate out of turns
without having the inner wheel spinning, yet does not make the car
understeer madly in turns. This is where a "limited slip" diff comes
into play.
In an open diff, the axle shafts can turn (more or less) independently
from the diff housing. This goes so far that, when the car is jacked
up, you can turn one wheel clockwise, and the other wheel will turn
counter-clockwise. The diff housing will not move at all during this
operation.
The infamous clutches will prevent this from happening. They connect
the axle shafts to the diff housing, but allow some slip. The more
clutches you pack in there, the less slip they will allow. The static
"clutch preload" does not depend on the torque of accelerating /
braking. Therefore, if you put too little preload in there, you still
will have wheel spin. If you dial in too much preload, OTOH, you get
basically a completely locked diff, which is even less desirable.
Fortunately, some folks (Smith mentions Mike Endean and Hewland)
developed the concept of "ramps". It is difficult to describe how
those ramps actually look, but they work like this: imagine a wedge
that is located between the axle gears and the diff housing. When you
apply power, the wedge will be pressed into the gap and make the two
parts turn simultaneously - with a certain amount of slip.
The force with which the wedge, or ramp, links the two parts depends
on the torque applied (the more torque, the greater the force, the
less slip allowed) and on the angle of the ramp - the ramp angle. A
30° angle will transmit the greatest force and give the least slip.
(even sharper wegdes would supposedly give even higher pressure and
locking power, but are not used, apparently.) A 90° angle is not
really a wedge or ramp anymore, but a stop, and will not exert any
pressure.
The real nice aspect of this design is that you can use two different
wedges, one for accelerating, and one for engine braking. When
accelerating, the engine gives torque to the axles and the wheels, and
the power, or drive side ramp comes into effect. When engine braking,
the wheels are giving torque to the engine, and the coast side ramp
starts working.
Therefore, you could use a setup like 30/90 (30° power side ramp angle
/ 90° coast side ramp angle) to get very little diff slip while
accelerating, and a completely open diff while coasting. I assume that
the transition between "almost fully locked" and "open" (and vice
versa) would be rather harsh, though, and might unsettle the car in
mid-corner when you step on the throttle again. The clutches are used
to give a certain amount of lock all the time and smoothen the
transition between coast and power phase.
Excuse me now, I have some testing to do at Monza. :)
5th Doctor
Joel Willstein <jaw...@sprynet.com> wrote in message
news:7o1m3p$qb9$1...@juliana.sprynet.com...
will begin to lockup sooner as you apply throttle. The higher the value,
the sooner the lockup.
>
> 2- The more clutches the tighter the rear. Yet most of the latest setups
> have gone to 4 clutches rather than 2 for the Lotus and Ferrari. From your
> explanation,I would think that 2 would be a better choice.
push too much when I'm trying to power out of a turn. The rear tires don't
want to break loose as easily. With 4 clutches in my setup, the rear wants
to break loose very easily, and I may spin it under power,or worse ,have to
lift exiting a turn to gather it up. I use 3 clutches in my setup. I use
basically the same setup for every road course, and a different setup for
ovals.
>
> At the start of the race when I apply the gas (no matter how
easy),the
> car pulls violently to the left. I always get left behind. Once I'm
> going,the steering is as it should be. This problem was never this bad
until
> I installed the patch and started using a MSFF wheel rather than my T2.
Slow
> corners that require 1st or 2nd gear usually wind up with violent
oversteer
> when I apply the power.
Maybe your setup?? I dunno. I don't use a FF wheel. My suspension is
symetrical, I don't use the clutch for starts, and I can usually launch the
car straight.
>
> Joel Willstein
> jaw...@sprynet.com
>
>
>
Jim Allison
Here's my take on this (I hope I'm close to being on the right track, so to speak -
comments please!):
1. More/faster locking of the differential results in more/faster oversteer
response.
2. Decrease the power side ramp angles to quicken the locking and thus increase turn
exit oversteer.
Increase the power side ramp angle to slow the locking and thus decrease turn
exit oversteer.
3. Decrease the coast side ramp angles to quicken the locking and thus increase turn
entry oversteer.
Increase the coast side ramp angle to slow the locking and thus decrease turn
entry oversteer.
(I change an 85/30 setting to an 85/45 setting when I'm into strong oversteer on
turn entry).
4. Add clutches to increase mid corner oversteer.
Remove clutches to decrease mid corner oversteer.
5. Do all the above before adjusting anything else (??)
I'm not quite sure of the mid-corner contribution of the ramps as your note
indicates that they
change both the force (locking?) and the slip (speed of locking?).
Wolfgang Preiss wrote:
> <snip snip>
>
> The force with which the wedge, or ramp, links the two parts depends
> on the torque applied (the more torque, the greater the force, the
> less slip allowed) and on the angle of the ramp - the ramp angle. A
> 30° angle will transmit the greatest force and give the least slip.
> (even sharper wegdes would supposedly give even higher pressure and
> locking power, but are not used, apparently.) A 90° angle is not
> really a wedge or ramp anymore, but a stop, and will not exert any
> pressure.
>
> <snip snip>
Wolfgang Preiss
>Excuse me now, I have some testing to do at Monza. :)
I know it's lame to follow-up one's own messages, but I did the
testing and wanted to share the results.
So I went to Monza and took a close look at my current ride, a Ferrari
with a modified Alison Hine setup (modified means I changed the
gearing and adjusted the roll bars and braking bias according to my
personal needs, but left the rest unchanged. This setup used to be
"Ali Silverstone neutral", not the Monza setup which has still too
much understeer for my liking.)
I was surprised to find the setting for the ramp angles set to 85/30.
This should mean "little lock under power / lots of lock while
coasting" according to what I've learned from C. Smith's book. More or
less the opposite of what I expected to be a good setting...
Since many people claim that the numbers in GPL actually mean the
opposite to what Smith says in his book, I did a little skidpad
testing. I reduced the number of clutches to the minimum (in order not
to dilute the results regarding the ramp angles) and tested four
different extreme configurations.
[As an aside: each ramp can have 30, 45, 60, or 85° of angle. It's 85
instead of 90 since the 90° angle parts tended to chip, according to
Smith. I find the pulldown menu in GPL somewhat confusing for a
beginner: since all combinations are allowed, *two* pulldown lists of
four items each would have been handier than one with 16 options.]
I started doing donuts on the front stretch at Monza and found the
following:
85/30 - only inside wheel leaves skidmarks
85/85 - again, skid marks only by the inside wheel
30/85 - both wheels leave marks
30/30 - both wheels leave skid marks
This conclusively proves two things:
1. The first number refers to the power side, the second to the
coasting side. Just as one would expect in reality - but this is
software, so I thought it deserved a special mention. :)
2. A higher number means less lock-up of the diff, a lower number more
lock-up. Sorry, 5thDoc, but you have to re-evaluate your info. Smith
is right.
Well, now I took the car with a 30/85 diff for a spin - literally.
While braking for Parabolica on the outlap, the rear of the car
overtook me. And no, this usually doesn't happen to me ( not anymore,
not all the time, at least.) At first, I was - unpleasantly -
surprised. But it really isn't that surprising when you think about
it: a locked diff means the car is going in a straight line - which is
what you want when braking for Parabolica! An open diff, OTOH, makes
turning easier. But I don't want to turn when braking at full speed.
(If you've seen today's German GP, you know what good a spinning car
at 300 km/h is... ;)
But the change made it much easier to induce throttle oversteer in
mid-corner. A bit *too* easy, to be frank, but a step in the right
direction. I drove a bit with a 45/60 ratio and will explore some
other ratios as well. Suffice it to say that this setting has quite
some effect on the car's handling. Try playing with it!
Wolfgang Preiss
>Excellent info Wolfgang. I have to get that book.
>
>Here's my take on this (I hope I'm close to being on the right track, so to speak -
>comments please!):
>
>1. More/faster locking of the differential results in more/faster oversteer
>response.
It depends, I'd say. Let's assume a RWD car with a locked diff: if you
are coasting slowly, the unwillingness of the rear axle to turn will
induce understeer. If you are on the throttle, however, both rear
wheels will eventually spin under power and you will have oversteer.
With an open diff, the inside wheel will spin whereas the outside
wheel will stay in its track and provide lateral force, so there is no
oversteer. And no acceleration worth speaking of. ;)
>2. Decrease the power side ramp angles to quicken the locking and thus increase turn
>exit oversteer.
> Increase the power side ramp angle to slow the locking and thus decrease turn
>exit oversteer.
Under power, yes.
>3. Decrease the coast side ramp angles to quicken the locking and thus increase turn
>entry oversteer.
> Increase the coast side ramp angle to slow the locking and thus decrease turn
>entry oversteer.
> (I change an 85/30 setting to an 85/45 setting when I'm into strong oversteer on
>turn entry).
This depends entirely on how you approach the corner. The lower the
coast side ramp angle is, the more stable the car will be while
(engine) braking in a straight line. And the less willing will it be
to turn. If you are trail braking into the turn, a lower angle will
mean more understeer. I agree with the first part of your statements -
it's the part after the "thus" that I'm not sure about.
>4. Add clutches to increase mid corner oversteer.
> Remove clutches to decrease mid corner oversteer.
This is under dispute among the authorities. Dave Kaemmer agrees with
you, Alison Hine disagrees. I have no opinion yet (and am no authority
either.) :)
compare http://simracing.com/alison/gpl/ferrari.htm
>5. Do all the above before adjusting anything else (??)
After fiddling with the ramp angles this afternoon, I tend to agree.
They are pretty influential.
>I'm not quite sure of the mid-corner contribution of the ramps as your note
>indicates that they
>change both the force (locking?) and the slip (speed of locking?).
I will try to make my terminology industry-standard compliant in the
future. :) It seems I have to resort to a crude ASCII rendering
again... This is my impression of the diagram on page 7-28 in Smith's
book:
_______
| |d
| |||
\ |||
_\ b |||
/a\\ |||_______e______
\_// |||
/ c |||
/ |||
| |||
|_______|
The huge lump in the middle is the side gear ring, aka ramp body.
(a) - the planet bevel gear, which is supposed to be round. :)
(b) - the coast side ramp.
(c) - the power side ramp. (Both ramps have the same angle in this
example. Too bad ther aren't "/" signs with different angles. :)
(d) - the clutch packs.
(e) - the axle.
Now, when the car accelerates, the bevel gear is pressed against the
power side ramp, which in turn is pressed to the right against the
clutches. This maximizes the lock of the diff:
_______
| |d
| ----> |||
\ |||
\ b |||
_ \ |||_______e______
/a\/ |||
\_/ c |||
/ |||
| ----> |||
|_______|
When the car is coasting, the same happens on the other side:
_______
| |d
| ----> |||
\ |||
/a\ b |||
\_/\ |||_______e______
/ |||
/ c |||
/ |||
| ----> |||
|_______|
Now, what I wanted to say is simply that, when there are little or no
clutches, the transition between coasting and accelerating in mid
corner might be a bit harsh. In the worst case, it could go from "full
lock" to "no lock" (when the bevel gear is in the middle) to "full
lock" again within fractions of a second. I just feel this could be
problematical.
>Wolfgang Preiss wrote:
>
>> <snip snip>
>>
>> The force with which the wedge, or ramp, links the two parts depends
>> on the torque applied (the more torque, the greater the force, the
>> less slip allowed) and on the angle of the ramp - the ramp angle. A
>> 30° angle will transmit the greatest force and give the least slip.
>> (even sharper wegdes would supposedly give even higher pressure and
>> locking power, but are not used, apparently.) A 90° angle is not
>> really a wedge or ramp anymore, but a stop, and will not exert any
>> pressure.
>>
>> <snip snip>
>>
>> Therefore, you could use a setup like 30/90 (30° power side ramp angle
>> / 90° coast side ramp angle) to get very little diff slip while
>> accelerating, and a completely open diff while coasting. I assume that
>> the transition between "almost fully locked" and "open" (and vice
>> versa) would be rather harsh, though, and might unsettle the car in
>> mid-corner when you step on the throttle again. The clutches are used
>> to give a certain amount of lock all the time and smoothen the
>> transition between coast and power phase.
--
Steve Blankenship
>I have messed with these settings alot, and, at least on my machine, the
>lower the number on the power side, the more I gotta mash the gas to
>accelerate. what gives?
I've seen the same initial acceleration lag when testing low angles on the
power side. My guess is that with more lockup(lower #'s), the peaky power
curves make initial wheelspin a bit tougher to induce. When it comes, though,
you've got a problem, since both rear wheels have checked out, grip-wise.
Instant panoramic view. Nosir, I don't like it. In fact, I've yet to find a
use for less than an 85 ramp angle on the power side. I know it doesn't ring
quite true to life, but the car's a beast with low power side angles, and my
basic setup philosophy is to just keep twisting all the knobs until the Lotus
stops trying to kill me, then break them off.
Cheers,
Steve B.
5th Doctor
> 2. A higher number means less lock-up of the diff, a lower number more
> lock-up. Sorry, 5thDoc, but you have to re-evaluate your info. Smith
> is right.
to floor the gas to get the car to move off pit lane, whereas with diff
settings of 85/30 I can ease into the gas and the car starts to roll easily.
Help me Obi Wan, your my only hope :)
5th Doctor
Smith, and maybe the ISBN (sp?) number, so I may get my ignorant hands on a
copy?
Kenny L.
the 5th Doctor
size 3 hat, size 13 shoe
Steve Blankenship
>I know it's lame to follow-up one's own messages, but I did the
>testing and wanted to share the results.
Don't apologize; it's called follow-up, and it's appreciated!
>Well, now I took the car with a 30/85 diff for a spin - literally.
>While braking for Parabolica on the outlap, the rear of the car
>overtook me.
Gee, that NEVER happens. :-) But with an 85 coast-side angle, it's probably
almost impossible to avoid there.(unless you start braking in Ascari) That
pretty much mirrors what I've settled on; for really heavy straightline
braking, go to low coast angles and more clutches.
>But the change made it much easier to induce throttle oversteer in
>mid-corner. A bit *too* easy, to be frank, but a step in the right
>direction.
Yep. I've found that using 45 or 60 on the coast side (instead of 30) makes it
easier to adjust my line with slight changes in throttle position. But
suspension settings that are neutral @ 30 will give you some nasty
lift-throttle moments if you try them @ 60. A touch more tweaking settles
that.
>I drove a bit with a 45/60 ratio and will explore some
>other ratios as well. Suffice it to say that this setting has quite
>some effect on the car's handling.
Indeed! My current interest is clutches. I'm convinced that less is more, and
only tracks with very heavy braking zones need more than two, at least for the
Lotus. I only use one at Brands and Monaco, and wish I could get by with it at
more tracks. But getting the car hauled down from speed with one clutch
is......interesting.
The journey continues.
Neil Raine
>
> At the start of the race when I apply the gas (no matter how easy),the
> car pulls violently to the left. I always get left behind. Once I'm
> going,the steering is as it should be. This problem was never this bad until
> I installed the patch and started using a MSFF wheel rather than my T2. Slow
> corners that require 1st or 2nd gear usually wind up with violent oversteer
> when I apply the power.
I wonder if this is due to the slow-speed variable steering ratio that
Papy put in to allow easier negotiation of slow-speed turns?
Apparently, at speeds below 60mph, the steering ratio is set somewhere
between 7:1 and the ratio you specified in the setup (proportionate to
speed), so when you start off the steering will be very twitchy indeed
(ie. at 7:1).
This can be turned off in 1.1 using disable_steer_ratio (or something
like that) in the core.ini, so it may be worth trying this.
I think it's explained on the vroc site under Alison Hine's pages
somewhere.
Wolfgang Preiss
I tried to duplicate this behavior, but my findings are inconclusive.
It seemed indeed as if the car needed a tiny bit more throttle to
start rolling with 30/30. But without telemetry data, the difference
is too subtle for me to be sure.
I have no idea what could cause this behavior. What conclusions do you
draw from your observation?
Wolfgang Preiss
>I am humbled by your skills.
No skills involved. :) I really did not have the faintest clue about
all this when I started the thread. When I had read the pages from the
book and the (conflicting) info in RAS, I just applied the ole
scientific method to figure out how this was modelled in GPL. It seems
*again* as if GPL accurately simulates the behavior of the real thing.
This sim never fails to impress me. :)
>Please, may I know the title of the book by
>Smith, and maybe the ISBN (sp?) number, so I may get my ignorant hands on a
>copy?
AUTHOR: Carroll Smith (note the spelling: two 'r's, two 'l's)
TITLE: Drive to Win
ISBN: 0965160009
Amazon has it in stock. I don't want to appear ungrateful, but I
wasn't overly impressed by the two-page excerpt that I read. First of
all, the text did not manage to convey the info to me on first
reading. And not on second or third reading either. This is pretty
technical stuff, so it's probably not Smith's fault, but I can imagine
a more accessible way of explaining a limited slip diff to amateurs
like me.
Secondly, the two pages contain some typos ("toque" instead of
"torque", "Powr" instead of "Power" - although this might be
intentional in a proper name ("Hewland Powr Flow".) Yet, when there is
one obvious typo, how can one be sure that this isn't one either?) I'm
usually pretty tolerant of typos, but in a book, they are more often
than not a sign of sloppy production
Smith's strong point seems to be his experience in racing. If you're
looking for "How do I use this?" info, you've come to the right place.
If your approach is more in the vein of "How does this work?", there
might be better books. What made me understand the principle wasn't
Smith's text but a small diagram on one of the pages.
But then again, I only read two pages, so I might not be doing him
justice.
Richard Walker
message <37a74ad2...@news.rz.uni-sb.de> :
>I don't want to appear ungrateful, but I
>wasn't overly impressed by the two-page excerpt that I read. First of
>all, the text did not manage to convey the info to me on first
>reading. And not on second or third reading either. This is pretty
>technical stuff, so it's probably not Smith's fault, but I can imagine
>a more accessible way of explaining a limited slip diff to amateurs
>like me.
The chapter in the book is some 15 pages long. Judging by your comments
about the typos, I presume that the extract you read was from some way into
the chapter and therefore didn't include the section on "basics". If so,
that may explain the difficulty you had.
>Secondly, the two pages contain some typos ("toque" instead of
>"torque", "Powr" instead of "Power" - although this might be
>intentional in a proper name ("Hewland Powr Flow".) Yet, when there is
>one obvious typo, how can one be sure that this isn't one either?) I'm
>usually pretty tolerant of typos, but in a book, they are more often
>than not a sign of sloppy production
I'm usually quite sensitive to typos, but having read the book several
times I must admit that I missed both of those until I just searched for
them <g>. On that basis there might be plenty more but I certainly didn't
get the overall impression that the production is sloppy. Maybe I was just
too engrossed with the content to bother about the typos though <g>
>Smith's strong point seems to be his experience in racing. If you're
>looking for "How do I use this?" info, you've come to the right place.
>If your approach is more in the vein of "How does this work?", there
>might be better books. What made me understand the principle wasn't
>Smith's text but a small diagram on one of the pages.
>
>But then again, I only read two pages, so I might not be doing him
>justice.
That's a fair judgement IMO.
Cheers,
Richard
5th Doctor
setup guide, and I found my thinking was ass-backwards. I am glad I first
responded with incorrect info, then someone replied with correct info, got
me thinking, then spent a day playing with diff settings.
I ended up with 30/30 and one clutch for my lotus, and it's much easier to
drive especially in the high speed turns. Not allot of work to get 1:29's
at monza, but the car sure is different.
More practice.
Thanks everyone.
5th Doctor
> "5th Doctor" <tyna...@SPUNKinreach.com> wrote:
>
> >
> >> 2. A higher number means less lock-up of the diff, a lower number more
> >> lock-up. Sorry, 5thDoc, but you have to re-evaluate your info. Smith
> >> is right.
>
> >Ok. Now I'm kinda confused. If I set my diff at 30/30, I pretty much
have
> >to floor the gas to get the car to move off pit lane, whereas with diff
> >settings of 85/30 I can ease into the gas and the car starts to roll
easily.
> >Help me Obi Wan, your my only hope :)
>
> I tried to duplicate this behavior, but my findings are inconclusive.
> It seemed indeed as if the car needed a tiny bit more throttle to
> start rolling with 30/30. But without telemetry data, the difference
> is too subtle for me to be sure.
>
> I have no idea what could cause this behavior. What conclusions do you
> draw from your observation?
That I'm probably brain dead. Seems before the 1.1 patch, it was allot
worse.
I figure, getting the car rolling is not a big factor. The benefits <sp?>
of a 30/30 diff far outweigh the drawbacks. I've settled on a 30/30 one
clutch.
Thanks
Ian P
news:hg_o3.224$T5.1...@news.inreach.com...
>
> Joel Willstein <jaw...@sprynet.com> wrote in message
> news:7o1m3p$qb9$1...@juliana.sprynet.com...
> >
> > 5th Doctor wrote in message <1jDo3.83$T5....@news.inreach.com>...
> > 1- Almost every setup I've ever seen uses a ramp angle of 85/30. From
your
> > explanation,I take this to mean that the rear locks up slower when
> applying
> > gas as well as locking up slowly when getting off the gas and on the
> brakes.
> > Or would one be better off using a lower power number?
> Not exactly. With a power side value of 85 (the highest available) the
diff
> will begin to lockup sooner as you apply throttle. The higher the value,
> the sooner the lockup.
> >
The lower the number the sooner the lockup occurs
> >
> > At the start of the race when I apply the gas (no matter how
> easy),the
> > car pulls violently to the left. I always get left behind. Once I'm
> > going,the steering is as it should be. This problem was never this bad
> until
> > I installed the patch and started using a MSFF wheel rather than my T2.
> Slow
> > corners that require 1st or 2nd gear usually wind up with violent
> oversteer
> > when I apply the power.
>
> Maybe your setup?? I dunno. I don't use a FF wheel. My suspension is
> symetrical, I don't use the clutch for starts, and I can usually launch
the
> car straight.
> >
I use a MSFF wheel and can make straight starts nearly all the time even
with assymetrical suspension.
Try altering the linearity slider and/or steering ratio, it makes quite a
difference.
BTW mine is nearly totally linear about 1/8 th from left and I use the
highest steering ratio I can get away with at each track. ie 14-1 at Monaco
18-1 at Spa and 16-1 at Monza and I still use the standard steering ratio
adjust.
--
Ian Parker
ian.p...@btinternet.com
UKGPL League
http://start.at/greenflag
Mark Aisthorpe
Neil Raine <ne...@iota.co.uk> wrote in message
news:37A580...@iota.co.uk...
> Joel Willstein wrote:
> >
> > At the start of the race when I apply the gas (no matter how
easy),the
> > car pulls violently to the left. I always get left behind. Once I'm
> > going,the steering is as it should be. This problem was never this bad
until
> > I installed the patch and started using a MSFF wheel rather than my T2.
Slow
> > corners that require 1st or 2nd gear usually wind up with violent
oversteer
> > when I apply the power.
>
> Papy put in to allow easier negotiation of slow-speed turns?
>
> Apparently, at speeds below 60mph, the steering ratio is set somewhere
> between 7:1 and the ratio you specified in the setup (proportionate to
> speed), so when you start off the steering will be very twitchy indeed
> (ie. at 7:1).
>
> This can be turned off in 1.1 using disable_steer_ratio (or something
> like that) in the core.ini, so it may be worth trying this.
>
> I think it's explained on the vroc site under Alison Hine's pages
> somewhere.
I think you could be right on this, i've been experimenting with my core.ini
settings
for my wheel (MSFF), and have currently turned of the steering ratio hack
and I'm
sure it feels easier to control at lower speeds, I was always spinning
coming out of
the hairpin at spa for instance, but now its a lot easier,
on the other hand now i cant get round a lot of the bends at Monaco, just
not enough
steering lock.
Mark
London UK
Michael E. Carver
last few weeks with ramp angles and clutches as well. I first started
with the coast-side in hopes of getting better speed through some of the
long sweeping corners. It can help, and when combined with other
settings it can help alot. However, I have found that in order to
balance out the car with a ramp angle of 85/45 or 85/60, I usually have
to soften the rear (either spring rate or ARB).
When testing with the power side, I couldn't find much use for it at
most tracks. It is extremely difficult to apply power and keep the car
straight (however, this can be compensated by adding more clutches).
Since most tracks were I am concerned with apply alot of power it is on
the straights (or while straightening the car coming out of a turn), I
did't find much advantage to lowering the power side ramp angle. So far
the one track where I have found it can be used is Monaco, where most of
the straights aren't straight at all. I have been successful at using a
60/60 setting at Monaco (however only after considerable tests with
different spring rates and ARB than normally used).
The key is not just changing the ramp angles and expecting to find
favorable results. This setting drastically alters the way the car
handles and must be matched with a different philosophy with spring
rate, ARB and camber settings along with clutches and sometimes even
tire pressure (what did I leave out?).
--
**************************** Michael E. Carver *************************
Upside out, or inside down...False alarm the only game in town.
mca...@teleport.com http://www.teleport.com/~mcarver
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./. [- < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=
Joel Willstein
Michael E. Carver wrote in message ...
>The key is not just changing the ramp angles and expecting to find
>favorable results. This setting drastically alters the way the car
>handles and must be matched with a different philosophy with spring
>rate, ARB and camber settings along with clutches and sometimes even
>tire pressure (what did I leave out?).
And I use to think that ICR2 was hard to setup a car in.
Joel Willstien
jaw...@sprynet.com
Wolfgang Preiss
>The key is not just changing the ramp angles and expecting to find
>favorable results. This setting drastically alters the way the car
>handles and must be matched with a different philosophy with spring
>rate, ARB and camber settings along with clutches and sometimes even
>tire pressure (what did I leave out?).
Bump and rebound dampers. :) Anything you change in your setup
influences everything else. Trying to figure this out often induces
pain between my ears. But it's fun if you get it working. :)
I experimented a bit with the ramp settings in Monza (still the only
track I'm consistent enough on to properly evaluate setup changes) and
found that 60/30 works better for me on that track than the previous
default of 85/30. Especially in Curva Grande it is easier to keep the
car away from the armco. In Ascari, the 85° power ramp angle allows
some wheelspin of the inside wheel with my setups. The 60° angle cures
this.
OTOH, I need the 30° coast side angle to keep the car straight when
braking for Parabolica. 60° also works, but the car becomes more
nervous - too nervous for longer races.
My main problem with setups is not to create one that's good to drive.
It is to create one that's good to drive *and* fast. I tend to build
cars that are nice but slow...
5th Doctor
clutches, also took 5# out of rear springs, 2/2 on the rear shocks, 18 psi
in the rear tires. My Lotus now is much easier to steer with the throttle,
I may "hang it out" with confidence. Very sensitive to throttle input
changes (glad I have a PDPI) but with a little practice I found that it
behaves predictably. It's a beast with cold tires, though. But, after a
couple of laps, I can do 1:29's at Monza all day. I'm very happy we all had
this discussion. Thanks to all who joined in.
Wolfgang Preiss <wo...@gmx.net> wrote in message
news:37aaa4f0...@news.rz.uni-sb.de...