How to Come Down A Steep Grade
hazen...@webtv.net
sizeable RV. I'm an ex- trucker with many years of experience hauling
oversize loads in the Sieara Nevada mountains . Unfortunately , when you
purchase or rent a big RV it does not come with instructions so I'm
going to give you some free tips on one of the most dangerous parts of
driving : coming off a long hill.
First , let's talk about loading . Since you probably have never
weighed your rig when she's loaded , you might be unpleasantly surprised
that she's OVERLOADED ! The GVW ( gross vehicle weight ) should not be
exceeded . Any truck stop will gladly weigh your rig ( about five bucks
) . If you are overloaded you are exceeding your braking capacity . In
the event of a serious accident , what's left of your rig will be
weighed . If you've exceeded the GVW , you may well be found at fault
in the wreck . Not good . Don't over load her .
Now , as you aproach the downdrade , size up the situation . How
steep is it . 6% is steep . anything over that is very steep . How long
is the grade ? More than a mile is getting serious . If there are signs
warning big trucks about the grade , you heed them too . You ARE a big
truck . So here's watcha do : select the gear that you know you
would come UP the hill in . If you have an automatic , ( most now are 4
speeds ) it probably would come up a steep hill ( 6%) in second gear .
If it's a very steep hill , drop her in first . Do all this BEFORE you
start down & be going slow enough that you don't over-rev the engine .
Slow down now , not later . If traffic is behind you , ( especially big
trucks ) , pull over & let 'um by . We're RVin' , not in a hurry
remember ? We're never in a hurry . If you are , you chose the wrong
hobby . OK start off the grade . If the engine holds you back , great
, but it probably won't . So here's wacha do : put very light pressure
on the brake pedal . Just enough to hold your speed where you want it .
KEEP your foot ON the pedal . That's right . RIDE the brakes . LIGHTLY
!!! Don't " pump" them . RIDE them. LIGHTLY . If light pressure does
not hold you back , increase the pressure GRADUALLY and select a lower
gear. Bring your engine RPM's down so it will not over - rev the engine
as you drop a gear . Now you should be able to decrease pedal pressure .
Do not be tempted to go faster because you have traffic behind you . If
there is a GOOD , SAFE spot to pull over and you know the grade will
continue , pull over . Be courteous . Stay there a while , like 15
minutes . Give the " brakes a break " . Let 'em cool off . Go make a
sandwich or make love with momma ( hopefully that takes more than 15
minutes :-). We ain't in a hurry .
As you see the bottom of the hill , go ahead & gear back up & coast
MAKE SURE it's the bottom . Donner Pass is very decieving . Just about
the time you think you're there , you ain't .However , use flat spots &
up grades to cool your brakes .
Now , a little warning : Big trucks cannot stop AT ALL when their
brakes are hot . On occaision , a rooky trucker can lose his " binders "
If you see a big rig barreling up on you on a steep downgrade , he may
have lost control . He may also just be an idiot or as Reddog puts it ,
an " ARB " ( good name Bill ) . If possible get to the right . If he
rear-ends you , it's over . A good indicator of a bad hill is the odor
of hot brakes . Once you've smelled it , you never forget it . Actually
hurts your nose . This means you're on a bad - ass hill & trucks
frequent it . Watch your mirrors . Don't be bullied in to going faster
by a trucker . If he tailgates you , pull over IF you can . If not ,
try to ignore him . When he passes , turn him in . I hate to say it but
on a reply to one of my recent posts , a guy spoke of having truckers
busted by using his cell phone & exaggerating the problem by telling the
police dispatcher that he thought he might be drinking . Tailgating is
deadly and if it takes that drastic a measure to stop it , well so be it
Alot of truckers will read this . I'll get bitched at . Well , don't
tailgate & ya won't have a problem , will ya ? I'm pro - truck because
they get our "stuff" to us . EVERYTHING . But I'm dead set against
rotten drivers of ALL vehicles , ESPECIALLY trucks because they are very
deadly. Don't worry Bill & Lon , I won't have one of my little " truck
tantrums " .
I think I covered it but main thing I'm trying to do on this NG is
help us all stay alive . I've taken alot of flak from it & think I
helped a few folks . Met some real cool people on here too . What I
taught you today is the professional way to come down a hill . Mr two
million mile man. In a large car . Y'all be safe . Enjoy the ride .
Smile & wave .
One last thing . If you don't have a CB radio , get one , When a
trucker loses his brakes he generally starts screaming on the radio .
Channel 19 . If you hear it , get off the road if possible . It also
is a great way to find out how serious the grade is going to be . Have
some fun . Help others out . Be nice . It will come back on ya' .
Long John
http://community.webtv.net/hazencajun/JOHNSANTIQUES
Hugh
Hugh
hazen...@webtv.net wrote:
>
> I'm writing this article for new drivers who may have graduated to a
> sizeable RV. I'm an ex- trucker with many years of experience hauling
> oversize loads in the Sieara Nevada mountains .
good stuff snipped .
> Long John
>
> http://community.webtv.net/hazencajun/JOHNSANTIQUES
DRS
Great post !!!
Don
Den73740
you want, but only once too fast."
Mo
long downhill riding the brakes, remember to use a flat spot and don't jam
on the parking brake hard as the drums will be hot and when they cool the
brakes stay in the position you locked them and you can get warped drums.
Mo
--
BC & Western Canada Info at
http://members.home.net/mo-drew/
e-mail mo-...@home.com
"Strangers are just friends waiting to happen."
hazen...@webtv.net wrote in message
<15127-39...@storefull-298.iap.bryant.webtv.net>...
Ed J
--
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Ed J e...@attglobal.net
On my retirement adventure from the rolling hills of
the Southern Tier in New York State..... Traveling in my
1999 Dodge 2500 6-spd diesel, 1999 Sunnybrook 27RKFS 5th-wheel
John E. Balch
>An excellent post Long John, thanks.
>Hugh
>hazen...@webtv.net wrote:
>>
>> I'm writing this article for new drivers who may have graduated to a
>> sizeable RV. I'm an ex- trucker with many years of experience hauling
>> oversize loads in the Sieara Nevada mountains .
>good stuff snipped .
>> Long John
>>
>> http://community.webtv.net/hazencajun/JOHNSANTIQUES
YES, and I am going to make sure my CB radio is on.
John E. Balch
>There's the ol saying, "You can go down the mountain too slow as many times as
>you want, but only once too fast."
There are old truckers and bold truckers but no old bold truckers. The same
is said for airplane pilots.
hazen...@webtv.net
there are two schools of thought . You can see this in the CDL handbook
available free at your DMV. You should read this manual . The constant
pressure method is being challenged by the " stab & release " method . I
do not agree with stab & release but I doubt the guy who suggested it
ran Donner 6 times a week in an 18-wheeler for years . I NEVER lost
my brakes . Another point , If you have a vehicle with air brakes
LEARN TO ADJUST THEM . It's easy . Dying is a drag . Long John
PS thanks for all the compliments & e-mails .
http://community.webtv.net/hazencajun/JOHNSANTIQUES
Jefef1
wacha do : put very light pressure on the brake pedal . Just enough to hold
your speed where you want it . KEEP your foot ON the pedal . That's right .
RIDE the brakes . LIGHTLY !!! Don't " pump" them . RIDE them. LIGHTLY . If
light pressure does not hold you back , increase the pressure GRADUALLY and
select a lower gear. Bring your engine RPM's down so it will not over - rev the
engine as you drop a gear . Now you should be able to decrease pedal pressure .
>>
Long John,
I understand what you're talking about and I'm sure most other readers do, too
but some of the newbies and wannabes in this group who are really new to RV-ing
may misunderstand your advice. In order to avoid serious problems, I want to
add my 5 cents worth to your post.
Riding the brakes is NOT a safe practice whether you have hydraulic brakes or
air brakes. John explained a good way how you can find the right gear to
safely go down a steep grade, and his suggestion that you "ride" the brakes is
meant ONLY for the relatively short time it takes to adjust your speed so you
can downshift into the right gear. Do not try to "ride" them all the way down
over several miles.
Otherwise, use your Pacbrake or Jake Brake to slow your RV - if you have one or
the other. "Riding" the brakes will eventually lead to overheating and loss of
the ability to brake at all. Although air brakes are not as sensitive to
overheating as hydraulic brakes are, they, too will eventually quit on you if
you try to go down a long, steep hill with your foot constantly on the pedal.
I hope this clarifies a potential misunderstanding.
No offense meant, Long John.
Jeff
dixie...@pbtcomm.net
'knew' everything, but thanks to these generous posts, I have just
learned a bunch of 'new stuff' all of which I will keep in mind on my
next trip on I-40 through the mountain passes. Thanks again guys.
Chris
AJKing554
safely decend mountain grades:
>So here's wacha do : put very light pressure
>on the brake pedal . Just enough to hold your speed where you want it .
>KEEP your foot ON the pedal . That's right . RIDE the brakes . LIGHTLY
>!!! Don't " pump" them . RIDE them. LIGHTLY .
I don't care how "lightly" you ride them, if you do this in a vehicle with
hydraulic brakes, you WILL overheat them and lose most if not all of your
braking capability. This method may work for air brakes on big trucks and
large coaches, I don't know, but it is definitely incorrect for the hydraulic
disk systems used on gas engine coaches.
Alan
ajki...@aol.com
hazen...@webtv.net
/ jake , great . They help. No Jeff , I meant what I said . LIGHT
continual pressure . If you keep speed down , gears down , LIGHT
pressure ON the brakes they WILL NOT overheat. Get A CDL manual. The
government wrote it , not me . You'll see the arguments too. Scientists
can't decide . Go down Donner . They have signs for rookies like (
Light brake pressure . HOLD 'EM ) OK Let 'er drift . ) Just written
like that . If you use engine compression to hold you back doing 5 miles
an hour , a large car will give you what we call a " peterbilt enema " .
That on a two lane ain't cool . If you are loaded light , you will
make it on compression . If not RIDE YOUR BRAKES . LIGHTLY . I have
over 2 million miles of asphalt behind me IN THE SIERRAS . I'm not "
steering you wrong . If your brakes over heat , you are over loaded (
common ) , you need a brake job , or you are holding too much pressure .
On air brakes I'm talking 5 pounds . That's nothing . When you hit 10 on
more than a mile you're gonna smoke 'em . On fluid brakes you have no
guage . Figure this : give them the same pressure it takes to to come
from 10 MPH to a halt in a block . THAT IS LIGHT PRESSURE . I've run
Donner THOUSANDS of times . Often with heavy equipment . Snowbird ,
Sherman , Colinga , Grapevine , & lots more . NOT on ONE could I hold
that load with Jake & gears alone & I never even SMOKED my brakes , much
less lost them . I was taught this method from an old man in the 70's .
He ran Donner as a two lane . His name was Bobbie Wayson from Reno. Any
Donner vet knew him. Donner killed truckers like lung cancer & heart
disease . It was deadly . I gladly stand behind my beliefs . Maybe a
highway patrolman , hopefully from California who can back his
credentials would comment ? One more thing : If you are scared to
come down at a reasonable pace , say 25 at least , turn on your flashers
Get on your CB & inform the up hill truckers you're a rookie & goin'
slow . Tell them every few minutes to warn the downhill truckers you're
taking it slow . They can save you from a Peterbilt enema . It'll be
your last one . And go get a CDL manual . FREE at ANY DMV . YOU ARE A
BIG TRUCK!!!!!! Drive it like one . Hell , go get the license & we
can help more people . Probably should have one anyway . The manual
can save your life . Should be one in the RV .
Long John Silver
ps no offense Jeff , but I feel strongly about this . It does work .
You will not lose your brakes . JS
http://community.webtv.net/hazencajun/JOHNSANTIQUES
Sky Walker
I guess this all come down to what is "Light"?
You have "THOUSANDS of times" and "Million miles" experience and you know what
is "Light".
Can average person know "Light"?
What is the possible outcome of wrong "Light"?
Have they second chance, if they listen to your advise but figure wrong the
"Light"?
Think about it!
IMHO, know your audience before you preach.
Remember, I do not say you are wrong or right on the "Light". I really don't
know the answer, but I certainly will not bet my life and my family's life on
that.
I prefer press brake hard to slow down and down shift gear and use engine
brake. I certainly care less blocking the traffic, if my life and my family's
life are in danger. Anyone feel free to sacrifice their life for not blocking
the traffic.
On Thu, 24 Aug 2000 14:58:35 -0700 (PDT), hazen...@webtv.net wrote:
=>In response to Jeff's letter : thanks for the input . If you have a pak
=>/ jake , great . They help. No Jeff , I meant what I said . LIGHT
=>continual pressure . If you keep speed down , gears down , LIGHT
=>pressure ON the brakes they WILL NOT overheat. Get A CDL manual. The
=>government wrote it , not me . You'll see the arguments too. Scientists
=>can't decide . Go down Donner . They have signs for rookies like (
=>Light brake pressure . HOLD 'EM ) OK Let 'er drift . ) Just written
=>like that . If you use engine compression to hold you back doing 5 miles
=>an hour , a large car will give you what we call a " peterbilt enema " .
=>That on a two lane ain't cool . If you are loaded light , you will
=>make it on compression . If not RIDE YOUR BRAKES . LIGHTLY . I have
=>over 2 million miles of asphalt behind me IN THE SIERRAS . I'm not "
=>steering you wrong . If your brakes over heat , you are over loaded (
Please do not tell me I am overloaded, when I am in the downhill rollercoaster
ride without a brake.
=>common ) , you need a brake job , or you are holding too much pressure .
Come on you advise people to use your method and if something goes wrong, our
life is gone, we need a brake job and we are overloaded.
Is this a sound advice?
If I were you, I would advise people not to use my method before the brake is
check and the weight is check, know what is "Light" and whatever necessary is
check.
=>On air brakes I'm talking 5 pounds . That's nothing . When you hit 10 on
=>more than a mile you're gonna smoke 'em . On fluid brakes you have no
=>guage . Figure this : give them the same pressure it takes to to come
=>from 10 MPH to a halt in a block . THAT IS LIGHT PRESSURE . I've run
=>Donner THOUSANDS of times . Often with heavy equipment . Snowbird ,
=>Sherman , Colinga , Grapevine , & lots more . NOT on ONE could I hold
=>that load with Jake & gears alone & I never even SMOKED my brakes , much
=>less lost them . I was taught this method from an old man in the 70's .
=>He ran Donner as a two lane . His name was Bobbie Wayson from Reno. Any
=>Donner vet knew him. Donner killed truckers like lung cancer & heart
=>disease . It was deadly . I gladly stand behind my beliefs . Maybe a
=>highway patrolman , hopefully from California who can back his
=>credentials would comment ? One more thing : If you are scared to
=>come down at a reasonable pace , say 25 at least , turn on your flashers
=> Get on your CB & inform the up hill truckers you're a rookie & goin'
=>slow . Tell them every few minutes to warn the downhill truckers you're
=>taking it slow . They can save you from a Peterbilt enema . It'll be
=>your last one . And go get a CDL manual . FREE at ANY DMV . YOU ARE A
=>BIG TRUCK!!!!!! Drive it like one . Hell , go get the license & we
=>can help more people . Probably should have one anyway . The manual
=>can save your life . Should be one in the RV .
=> Long John Silver
=>
=>ps no offense Jeff , but I feel strongly about this . It does work .
=>You will not lose your brakes . JS
=>
=>http://community.webtv.net/hazencajun/JOHNSANTIQUES
hazen...@webtv.net
less succeptable to heating . It's because air is expended upon
application . Fluid is not . Fluid gets old & less effective . It will
boil . Drain your system & put in the best fluid possible . I like
synthetics . If you feel the pedal going down ( air or fluid ) , start
looking for a place to pull way over . Fluid takes a while to cool . 20
minutes at least . I hope I haven't frightened anybody here . Losing the
brakes on a LEGALLY loaded RV is very rare.
I yearly haul my sailboat down Spooner Summit ( Hwy 50 from Tahoe to
Carson City ) with an old Ford F250. The Boat & trailer weigh about
9,000 pounds . This rig is overloaded . Spooner is a steady 6% + for
over 10 miles . I've never had trouble using my system .
One more thing : most nasty hills have escape ramps for runnaway
vehicles . If you lose your brakes , go on in . You'll need to be towed
out but it will save you . I'm still open to criticism & welcome it .
That's how we learn . I don't proclaim to know it all . I just have lots
of experience . Also remember hot days make hot brakes . Rain cools
them real nice . Also , I don't ever recall seeing a runnaway RV . They
are lighter & more efficient than a truck . I just don't ever WANT to
see one . Drive safe .
Long John
http://community.webtv.net/hazencajun/JOHNSANTIQUES
Steve Wolf
Rockies and not downshift. My rotors would be white hot with the brake
pressure required required to keep my speed down. Hell, the brakes in the
plastic Saturn would, too.
There's no such thing as gentle pressure when you don't downshift.
Gene Jackson <gjac...@gamewood.net> wrote in message
news:39a5c526...@news.gamewood.net...
> Tried this recently in my '34 Pace Arrow with 454 Chevy and C20
> tranny, caused my vacuum modulator valve to die and RV had to go to
> shop for repairs. Mechanic at the RV shop who has LOTS of big rig
> experience said to leave RV in regular drive, hold gentle pressure on
> brakes and DO NOT downshift automatic tranny in gasoline RV !!!
hazen...@webtv.net
http://community.webtv.net/hazencajun/JOHNSANTIQUES
hazen...@webtv.net
jokin' Listen to Mark & Long John .
http://community.webtv.net/hazencajun/JOHNSANTIQUES
hazen...@webtv.net
off the hill often enough. When she fades , give her more pressure & GET
OFF THE ROAD . !!!!! Or _------ take some of your water , waste ,
fuel , canned food , or throw out some passengers !!!!! WEIGH THE
RIG ! Colorado passes are LONG !!!
http://community.webtv.net/hazencajun/JOHNSANTIQUES
Robert Carr
pro's and con's of continual light brake pressure vs the
moderate-heavy stab at periodic intervals techniques. I use the
moderate-heavy stab method, but am not sure it is any better than
continual light method. I really have no way to evaluate the two
techniques.
Isn't the real problem being faced here related to the speed of the
downhill travel. Once I run out of lower gears, engine brakes, etc. I
have no choice but to apply brakes. What we are trying to prevent is
overheating of the brakes. This, to me, seems like a problem of trying
to balance the heat input with the heat output(dissapation) to some
acceptable level so that the brakes do not elevate above some critical
temperature. Consider a somewhat simple example. If a heavy rig uses
brakes to control speed at an average of 40 mph, they will complete a
5 mi downhill run in 7.5 minutes. If the same rig uses brakes to
control speed to an average of 2 mph, they will complete a 5 mi
downhill run in 150 min(2.5hrs). It seems to me that the rate of heat
input at 40 mph will be much greater than at 2 mph. At 2 mph there is
much more time to dissipate the heat input resulting in an overall
lower brake temperature rise. Now I don't recommend going down a hill
at 2 mph, but I think the example illustrates the dependence of heat
input rate on speed. So, in my non-expert mind, it seems that once
there is no lower gear and no more engine brakes, it becomes necessary
to select a proper decent speed. How that is done, I'm not sure. What
do you think?
Bob
On Thu, 24 Aug 2000 14:58:35 -0700 (PDT), hazen...@webtv.net wrote:
>In response to Jeff's letter : thanks for the input . If you have a pak
>/ jake , great . They help. No Jeff , I meant what I said . LIGHT
>continual pressure . If you keep speed down , gears down , LIGHT
>pressure ON the brakes they WILL NOT overheat. Get A CDL manual. The
>government wrote it , not me . You'll see the arguments too. Scientists
>can't decide . Go down Donner . They have signs for rookies like (
>Light brake pressure . HOLD 'EM ) OK Let 'er drift . ) Just written
>like that . If you use engine compression to hold you back doing 5 miles
>an hour , a large car will give you what we call a " peterbilt enema " .
>That on a two lane ain't cool . If you are loaded light , you will
>make it on compression . If not RIDE YOUR BRAKES . LIGHTLY . I have
>over 2 million miles of asphalt behind me IN THE SIERRAS . I'm not "
>steering you wrong . If your brakes over heat , you are over loaded (
>common ) , you need a brake job , or you are holding too much pressure .
>On air brakes I'm talking 5 pounds . That's nothing . When you hit 10 on
>more than a mile you're gonna smoke 'em . On fluid brakes you have no
>guage . Figure this : give them the same pressure it takes to to come
>from 10 MPH to a halt in a block . THAT IS LIGHT PRESSURE . I've run
>Donner THOUSANDS of times . Often with heavy equipment . Snowbird ,
>Sherman , Colinga , Grapevine , & lots more . NOT on ONE could I hold
>that load with Jake & gears alone & I never even SMOKED my brakes , much
>less lost them . I was taught this method from an old man in the 70's .
>He ran Donner as a two lane . His name was Bobbie Wayson from Reno. Any
>Donner vet knew him. Donner killed truckers like lung cancer & heart
>disease . It was deadly . I gladly stand behind my beliefs . Maybe a
>highway patrolman , hopefully from California who can back his
>credentials would comment ? One more thing : If you are scared to
>come down at a reasonable pace , say 25 at least , turn on your flashers
> Get on your CB & inform the up hill truckers you're a rookie & goin'
>slow . Tell them every few minutes to warn the downhill truckers you're
>taking it slow . They can save you from a Peterbilt enema . It'll be
>your last one . And go get a CDL manual . FREE at ANY DMV . YOU ARE A
>BIG TRUCK!!!!!! Drive it like one . Hell , go get the license & we
>can help more people . Probably should have one anyway . The manual
>can save your life . Should be one in the RV .
> Long John Silver
>
>ps no offense Jeff , but I feel strongly about this . It does work .
>You will not lose your brakes . JS
>
Gene Jackson
tranny, caused my vacuum modulator valve to die and RV had to go to
shop for repairs. Mechanic at the RV shop who has LOTS of big rig
experience said to leave RV in regular drive, hold gentle pressure on
brakes and DO NOT downshift automatic tranny in gasoline RV !!!
My check book has evidence now to support his recommendation.
Mark Morissette
>pro's and con's of continual light brake pressure vs the
>moderate-heavy stab at periodic intervals techniques. I use the
>moderate-heavy stab method, but am not sure it is any better than
>continual light method. I really have no way to evaluate the two
>techniques.
The only difference is that a speed increase that requires a "Heavy
Stab" to bring under control is probably too much of a speed increase
to begin with..
The commonly accepted, commonly trained, and most commonly used in
"real life" truck driving is the light, continual application only as
often as needed to maintain a controlled speed.. If a light
application can't keep things under control, you are either overloaded
to decend the hill to begin with, or are in far too high a gear.
---
Mark, Oshawa, Ontario, Canada
pepp...@spamcop.net
Marge & Stan
the exhaust brake. The Allison automatically shifts down to fourth, we
settle back and steer. Coming down I-70 into Denver, a 6 per-center, I
touched my brakes once. By the way, my purchased motorhome came with two
linear feet of instruction booklets on everything from how to start it to
how to dump it, including a professional video tape that covers, among other
things, safe driving techniques. Thanks for trying, I guess. Stan.
Jefef1
jake , great . They help. No Jeff , I meant what I said . LIGHT continual
pressure . If you keep speed down , gears down , LIGHT pressure ON the
brakes they WILL NOT overheat. >>
I don't argue against your 30 years of trucking heavy loads, John. I'm not a
professional driver. I currently have a 33,000 pound motorhome and at that I'm
about 45,000 pounds short of the weight of a loaded semi. Of course, my brakes
aren't designed for a large semi either. So far, my Pac has held me back fine
and when I applied the brakes often, I noticed that rubbery smell.
<< Get on your CB & inform the up hill truckers you're a rookie & goin' slow .
Tell them every few minutes to warn the downhill truckers you're
taking it slow . They can save you from a Peterbilt enema . It'll be your last
one . >>
Good idea ! This should help everyone on the road.
Happy trails !
Jeff
Jefef1
con's of continual light brake pressure vs the moderate-heavy stab at periodic
intervals techniques. I use the moderate-heavy stab method, but am not sure it
is any better than
continual light method. I really have no way to evaluate the two techniques. >>
Bob, if you have an RV (or truck) with air brakes, you deplete your air supply
with continual pumping. It's better to ride the air brakes with even pressure.
(I'm not gonna comment on what "light" is supposed to mean in the earlier
post.)
If you have hydraulic brakes, you will overheat your brakes if you ride them
for too long because the fluid comes to a boil and your breaking capability
quickly diminishes. So, here you should pump slowly.
It may be another topic for a discussion whether short pumps are really a good
idea. I, personally, object to the jerking action that results from sudden
braking action. I drive an RV. There are hundreds of items that get jerked
around all day long and wander a little every time I have to hit the brakes
strongly. If you drive a truck with securely tied down cargo you don't have to
worry about the cabinets opening and stuff flying out of them. Also, you
"rock" the RV if you break in a jerking fashion. That is unsafe in my opinion.
The driver of class B RV should follow different rules than the driver of a
fully loaded class C RV or a big class A RV, and the driver of a fully loaded
luxury bus probably handles his bus differently than a straight body truck
driver and a semi driver. Just think of the many differences between these
vehicles, I mean apart from the obvious size difference.
As I said in my post yesterday, there is plenty of room for misinterpretation.
John's original post was directed at drivers of bigger RVs. Everyone who's
ever had a heavy trailer in tow (heavy in relation to the tow vehicle) will
agree that you have to make "allowances" for the extra weight (GVW) when you
pull, when you go around curves, and certainly when you want to slow down. So,
I think we can all learn something from this discussion but we still have to
apply the newly gained knowledge in an intelligent fashion to our RVs otherwise
some readers may end up with air brakes and no air and the newbie in his Toyota
Camry with his shiny new pop-up in tow may be tapping his left foot in search
for the Jake brake. Okay, okay, I'm kidding.
Be safe.
Jeff
Greg Surratt
>I knew this might be a controversial subject . Yes , airbrakes are
>less succeptable to heating . It's because air is expended upon
>application . Fluid is not . Fluid gets old & less effective . It will
>boil . Drain your system & put in the best fluid possible . I like
>synthetics . If you feel the pedal going down ( air or fluid ) , start
>looking for a place to pull way over . Fluid takes a while to cool . 20
>minutes at least . I hope I haven't frightened anybody here . Losing the
>brakes on a LEGALLY loaded RV is very rare.
The fluid boils because of the pressure.
The brake drums and shoes overheat in both systems because of
friction. This overheating problem has nothing to do with the type of
actuation method.
Greg
Greg Surratt
wrote:
>x-no-archive: yes
>
>The problem with the constant brake method is you will toast the brakes in a
>light duty (up to 1 ton) pickup, especially a Dodge. I've read stories on
>this newsgroup about flaming tires on I70 west of Denver. Constant brake
>pressure might be great for the pros in the big rigs but you folks in the
>pickups better just "get on em with moderate pressure, then GET OFF EM!"
A true statement. Stab and release on a big rig tends to build up
more heat than with a pickup (even with a big 5er - consider 80K vs
20K weights). And the heating and cooling cycle of the big rig brakes
with the temperatures involved tends to glaze the surface of the brake
shoes, resulting in the same effect as rubbing two pieces of glass
together to try to slow the rig down.
Greg
'98 3500 QC 4x2 Cummins ISB, Auto, 3.54:1,
Driftwood with Leather and all the heavy duty options.
'89 Nu-Wa Champagne Edition, 34 foot Fifth Wheel.
and 10 years OTR in KWs.
W F Sill
> . . . . .I meant what I said . LIGHT
>continual pressure . If you keep speed down , gears down , LIGHT
>pressure ON the brakes they WILL NOT overheat.
::sigh::
I have seen many responses to this bad advice and probably ought to
say nothing, but the fact is that it could easily be FATAL. The
gearing down advice is good as far as it goes, but I am concerned that
discussion about method A vs method B obscures the crucial point: if
you are relying on BRAKES to maintain a safe speed on long steep
grades you are going to destroy the brakes and probably crash.
No vehicle known to man has brakes designed to keep vehicle speed
under control on long steep grades. If you take the advice offered by
another party ("never shift down, use the brakes") you are guaranteed
the most exciting and possibly last ride of your life.
Having just returned from another 8500-mile trip across the country,
I wish to report the following observation: there are far fewer
flaming idiots on the road (percentage-wise) that there are wrriting
erroneous advice to this NG. Thank Heaven.
Will KD3XR ---- the Curmudgeon of Sill Hill
Before flaming, pause. I post to help rv'ers
and annoy morons. Whichever shoe fits, wear it.
W F Sill
in part:
> Mechanic at the RV shop who has LOTS of big rig
>experience said to leave RV in regular drive, hold gentle pressure on
>brakes and DO NOT downshift automatic tranny in gasoline RV !!!
See my other post on this totally idiotic and dangerous advice. Your
tranny did NOT die because of shifting down on grades. . . . but you
may if you take his advice.
W F Sill
>I can't fathom how I would drive my motorhome stripped bare and empty in the
>Rockies and not downshift. My rotors would be white hot with the brake
>pressure required required to keep my speed down. Hell, the brakes in the
>plastic Saturn would, too.
>
>There's no such thing as gentle pressure when you don't downshift.
Let the record show there is at least one instance in which I agree
with Steve. See other verbiaage on this topic.
Mo
I know
>this from proper training and first hand experience with a 97 Ford F250
>Powerstroke towing a 5er that weighed 13,000 loaded.
>
>Glenn in Den.
>
>"
Glenn -
Didn't they teach you how to calculate GCVW? If you come to BC you will
find that you are way over the limit and liable to
(a) a fine
(b) being made to leave the rig at the scales until you have something big
enough to legally tow it.
Mo
Hugh
Hugh
W F Sill wrote:
>
snipped
JOE NEAR
I agree both types would get hot, but because hydraulic systems are
designed to work with a non-compressible liquid they don't work well
with very compressible brake fluid vapor.
You may warp a disc or even have a brake fire with either, but the with
the hydraulic system when they overheat you could lose all braking.
Joe Near
Robert Carr
After reading your comments along with other subsequent responses, I
concluded that my explanation of using the "moderate-heavy stab
method" left a lot to interpretation. So, let me try to clarify.
North of LA there is a stretch of Interstate 5 called the Grapevine.
It is a downhill(northbound) stretch of about 5-6 mi at a grade of
6-7%. When I tow my Travel Trailer down that grade, I feel that I have
two choices. Put it in 2nd gear and plan on using a fair amount of
braking or put it in 1rst and use no braking. Since I estimate that
2nd gear, by itself, would not be able to hold me much below 55
mph(too fast for me), I choose to move over to the low speed truck
lane(posted at 35mph), put it in 1rst gear, apply a little throttle
and proceed down the hill at 35mph. It is necessary to apply a little
throttle, since 1rst gear provides a little too much engine braking at
this % grade. Now I make a judgement that this technique will work for
up to a 9% grade, of course requiring much less or no throttle on the
higher % grades. Above 9% grade, I believe that additional braking
will be required. My only experience has been on a 10-12% grade coming
out of Yosemite. This grade, running about 5-6 mi in length, is a
twisty mountain road with a good number of hairpin turns. In order to
make a somewhat graceful decent I needed to hold my speed to about
25mph. 1rst gear engine braking alone would not accomplish that task.
My technique, in addition to 1rst gear engine braking, was to apply
moderate braking at somewhat periodic intervals such that I
constrained my speed to between 25 and 35 mph. In other words I would
allow the rig to increase speed to about 35, apply constant moderate
braking until the speed dropped to about 25 and then release brakes
and allow the process to repeat. For some definition of what I call
moderate braking, I would say that I would decrease from 35 to 25 in
about 10-15 seconds? This is what I meant in referring to the
"moderate-heavy stab" method, but only to distinguish my technique
from constant light braking, which still scares me. I am not proposing
that my technique is the best or the only way to go, just the way I do
it. Any additional thoughts?
Bob
JOE NEAR
What kind of mountains has this guy driven in? Downshifting shouldn't
hurt if you do it at a reasonable speed. I can't imagine going down some
grades in "regular drive".
Joe Near
Pete Dumbleton
given liquid boils). The more pressure you apply, the less likely the
fluid will boil. Don't believe me, test it for yourself. Stand on your
brakes as hard as you can in your driveway (rig up a small hydraulic jack
to push on the pedal), I'll bet the pedal bends before the brakes boil or
before the fluid in the jack boils due to excess pressure.
The fluid boils because the cylinder and lines are right next to the heat
producing shoes, drums and discs and can't drain the heat fast enuf to
prevent temp rise and subsequent boiling. If the cylinders were out in the
middle of the axles, pushing a long lever arrangement, they wouldn't boil
at all.
If you have water in your lines, they will boil quicker because the
boiling point is lower. I understand from rec.autos.tech or something
like that , that one drawback to synthetics is that if water *does* get
into the system it pools at the lowest points, which are often the
cylinders, and can actually cause rust. Older brake fluids slowly absorb
water and lose effectiveness. Both should be changed.
Erich Coiner
> Greg Surratt wrote:
> >
Fluid takes a while to cool . 20
> > >minutes at least . I hope I haven't frightened anybody here . Losing the
> > >brakes on a LEGALLY loaded RV is very rare.
> > Greg
I lost my brakes one night in my legally loaded truck and camper.
Since it happened only once I suppose that makes it rare.
My 8600 GVW truck was loaded to 8500 pounds and I was towing a 2000
pound trailer. I was well within my GCWR of 17,000 pounds.
I was descending Townes Pass into Death Valley near Stove Pipe Wells
California.
This hill is 7 or 8% with straight sections about 1/2 mile long followed
by a curve that was posted at around 45 mph.
I would allow the rig to rise up in speed to around 55 mph. Then I would
apply moderate/firm braking to drop speed to 45. Go around the corner
and let the rig roll up in speed during next straight. Repeat process.
After about 10 or 12 of these corners, I smelled that hot brake lining
smell. I decided I better slow down a lot more so I hit brakes in the
middle of the straight away. The pedal went right to the floor!
By pumping it a couple times I was able to get enough brakes that
combined with downshifting the trans (manual not automatic) I was able
to come to a stop before the next corner.
The safe way to descend this particular hill was to put the transmission
in 3rd and let engine braking hold it down to 45 all the time. I know
because that is how I finished the rest of the grade AFTER waiting over
an hour for the brakes to cool and the pedal the get firm again.
The rarity of one of these events is NOT related to the weight of the
rig. It is related to the experience and intelligence of the person
behind the wheel. I'm not any more intelligent today than I was 6 years
ago, but I am more experienced and the problem has not reoccurred.
Erich
W F Sill
>Welcome back Will, glad it was a good trip.
>Hugh
Thanks, Hugh & others. It was a great trip. No calamities beyond a
chipped windshield and many enjoyable experiences. Each time we make
this run we get more emphatic in our choices of secondary vs main
highways. We are not gonna tell ya which ones are great but here is a
tip: 4 or more lanes does NOT necessarily provide for smoother travel
- or even faster travel.
We negotiated the Appalachians, Rockies & Cascades with no problems,
and the closest call we had occurred the last day on I-81 when all
traffic came to a sudden stop with no warning, thanks to a
shorter-than-usual run of orrange barrels!
Additional remarks on steep grades: In 8500 miles we saw evidence of
a fair number of "leaving roadway" wrecks in mountain country,
virtually always on descending grades and usually on curves. We were
fortunate not to see any happen or even still in place, so it's
impossible to deduce how many were rv's. We saw a small but
significant number of people apparently oblivious to the potential
danger of dragging the brakes on long grades - but most were in cars
and only a couple were trailing a plume of smoke!
My opinion: those who think they are OK using brakes to control speed
are mostly living on luck. In addition to the terrible damage being
done to their brakes, sooner or later they will will round a
descending curve too fast and find a moose/horse/rockslide etc and
suddenly find they have used up ALL the reserve braking power and will
simply be unable to stop.
W F Sill
his technique for a long grade where gearing down doesn't quite get
the job done:
> . . .In other words I would
>allow the rig to increase speed to about 35, apply constant moderate
>braking until the speed dropped to about 25 and then release brakes
>and allow the process to repeat. For some definition of what I call
>moderate braking, I would say that I would decrease from 35 to 25 in
>about 10-15 seconds? This is what I meant in referring to the
>"moderate-heavy stab" method, but only to distinguish my technique
>from constant light braking, which still scares me. I am not proposing
>that my technique is the best or the only way to go, just the way I do
>it. Any additional thoughts?
Additional? No. I have probably already written too much on this,
but allow me to re-iterate: the technique you suggest is fine but
the key to safe descent is not stab vs 'light' drag - but minimizing
the heat load on the brakes so you can use them as intended - to STOP
when necessary. No matter which method is used, it is essential to
sense when heat buildup is occurring, and STOP to let 'em cool if
necessary.
Robert Carr
I don't disagree at all with your comments. As you know these
discussions on descending steep grades invariably become a discussion
on continual light braking vs stab. I guess both techniques have been
taught to truckers over the years, one method or the other being
preferred at selected points in time. Your absolutely correct that we
want to minimize the heat build up on brakes. For me that is
achievable in two ways. First use gearing (engine braking) to the
maximum extent possible and second reduce the downhill speed. The
faster you go down the hill while using braking, the higher the rate
of heat build up. If the brakes start going away half way down the
hill, then pull over and stop and let them cool. In effect this is
reducing the average downhill speed.
As you know, I tend to look at things in a theoretical manner.
Although much simplified, I look at going down a hill as converting
potential energy into kinetic energy(speed). If a speed increase is
not desired, then braking is applied converting potential energy into
heat. Whether a person uses continual light braking or the stab
approach, the same amount of potential energy is converted to heat in
traveling from the top of the hill to the bottom. However, if the time
to travel from top to bottom is increased(lower average speed), then
the rate at which this conversion takes place is extended(lower heat
input rate). If the heat input rate and heat output(dissapation) rate
are suitably balanced(not necessarily equal), the brakes will not
overheat and will be there when needed.
One final thought. Speaking only for myself, I think it would be
easier to sense brake heat build up(fading) using the more
moderate/aggressive braking involved in the stab method, rather than
the continual light braking technique. I haven't given this a lot of
thought, but that is the way it seems to me.
Bob
On Sat, 26 Aug 2000 03:22:34 GMT, W F Sill <wi...@epix.net> wrote:
snipped previous reference
Robert Carr
of 1997. Got through that year without problems. In 1998 while going
under a overpass bridge under some kind of construction something
dropped and did a real number on the windshield right in front of the
driver. So I had it replaced. In 1999 on the first outing of the year
with the trailer a truck entered the highway from a service road. I
was closing on the truck, but still several hundred feet behind when
he threw up a stone or something and got the drivers side of the
windshield again. So I had that replaced. In 2000 on the first outing
with the trailer a small car decided to traverse from the left most
lane to the right most lane and threw up something and got the
windshield again. This time it wasn't quite so bad and was not
directly in the drivers view so I had it repaired with some kind of
pressure induced glue system. Supposedly it will prevent the crack
from spreading.
Although I don't remember ordering the option, I think my truck has an
object attractor mechanism on it. Been looking for the switch to turn
it off. Either that or it is all being caused by the fact that I
raised my deductible to $500 a few years ago.
Bob
W F Sill
>Hi Will, welcome back
Thanx.
>I don't disagree at all with your comments. As you know these
>discussions on descending steep grades invariably become a discussion
>on continual light braking vs stab. I guess both techniques have been
>taught to truckers over the years, one method or the other being
>preferred at selected points in time.
Yes, both have been taught, but for rv'ers generally there are some
very good reasons to avoid continuous dragging of brakes. You wrote:
> . . . .Your absolutely correct that we
>want to minimize the heat build up on brakes. For me that is
>achievable in two ways. First use gearing (engine braking) to the
>maximum extent possible and second reduce the downhill speed. The
>faster you go down the hill while using braking, the higher the rate
>of heat build up. If the brakes start going away half way down the
>hill, then pull over and stop and let them cool. In effect this is
>reducing the average downhill speed.
OK so far.
>As you know, I tend to look at things in a theoretical manner.
>Although much simplified, I look at going down a hill as converting
>potential energy into kinetic energy(speed). If a speed increase is
>not desired, then braking is applied converting potential energy into
>heat. Whether a person uses continual light braking or the stab
>approach, the same amount of potential energy is converted to heat in
>traveling from the top of the hill to the bottom. However, if the time
>to travel from top to bottom is increased(lower average speed), then
>the rate at which this conversion takes place is extended(lower heat
>input rate). If the heat input rate and heat output(dissapation) rate
>are suitably balanced(not necessarily equal), the brakes will not
>overheat and will be there when needed.
Also peachy, tho it can be argued that there are thermal differences
favoring one or the other, (Of course, in this arena it can be and is
argued that maximum = minimum, too! Hehehe. ) I like it when people
not only understand how things are, but take the trouble to understand
WHY things are the way they are!
>One final thought. Speaking only for myself, I think it would be
>easier to sense brake heat build up(fading) using the more
>moderate/aggressive braking involved in the stab method, rather than
>the continual light braking technique. I haven't given this a lot of
>thought, but that is the way it seems to me.
Well, it is easier for me, but as long as we remember the important
stuff (brakes are NOT designed for speed control) there is another
practical issue that weighs heavily in favor of the periodic stab
method vs "light" continuous application: Wheel brakes are heavy
machinery, built very strong but not very precisely. Because of this,
no two react *exactly* the same to light pressure. As a result, a
"light" (I keep putting that in quotes because nobody can agree on
what it means!) application may well cause one or two shoes/pads to
overheat and cause a serious problem while others have not even moved.
Those towing trailers are at MUCH greater risk from this phenomena,
since no trailer brake controller known to man can dependably match
the braking performance of the tow vehicle. Remember seeing smoking
brakes on a recklessly-driven "18-wheeler"? Almost always it is just
the trailer brakes.
Bottom line: IMO it is clearly better to get on 'em moderately and
intermittently (when engine braking won't quite get the job done).
That way all the brakes share the (heat) load. Best of all, avoid
touching them at all except to stop!
Bill Basham
when pulling a trailer with electric brakes.
As we all agree, the best way to come down a hill is with engine braking. If
you're stabbing and grabbing too often, that's the cue to slow down and
downshift. Also, a great way to increase engine braking a little is to turn up
the air conditioner all the way.
Theoretically, I think stab and grab dissipates more heat into the air, where
you want it. Hard braking heats up the surface of the drum/disc to a higher
temperature. Letting off the brakes improves the airflow over the disc a
little, and the transient high surface temperature means more heat goes into
the air, instead of being conducted into the disc. For a long period of
braking, more heat into the air means lower AVERAGE brake temperatures, which
is what heats the fluid and makes hydraulic brakes fade.
Big diesel trucks with air brakes are a different animal. The average brake
temperatures are higher because of the heavy loads, so the very high transient
temperatures produced by the stab and grab method might lead to a brake fire.
Also, riding the brakes while towing a trailer with electric brakes is pretty
uncertain. Trailer electric brakes aren't really adjustable precisely. Light
pressure on the tow vehicle brakes might be accompanied by heavy pressure on
the trailer brakes, leading to trailer brake failure or fires. For this
reason, I think stab and grab is the only way to go when towing a trailer.
Stab and grab and downshift! (not necessarily in that order)
Bill
Mike Niemela
like to share a recent experience about this.
Two weeks ago my bride found a '78 T-Bird that basically looks like it
just came off the show room floor. She has been looking for one for the
past few years since ours was destroyed by a fellow coming thru a red
light. The used car dealer told me that the brakes were "marginal" and
that they needed to be looked at. We bought the car knowing of this and
a couple of other defects. The used car dealer in this case amazed me
with his honesty.
I took the car to a remote location by way of seldom used streets and
did a series of stop tests. Under light brake load no problems were
noticed. When attempting a "panic stop" from 55 MPH the brakes would
hold well for a couple of seconds and then fade to practically nothing.
No soft pedal was noticed.
I pulled all four wheels and rear drums. The pads and shoes were nearly
new as were the calipers and wheel cylinders. The master cylinder
appears to be the original. Car has just over 60,000 miles showing and
appears to be the first time around.
Brake fluid in the master cylinder looked dirty. Hooked up the vacuum
system and pulled all the fluid out thru the calipers/cylinders and
flushed the system. Replaced the fluid with new synthetic and all of the
brake problems went away.
I suspect the fluid had never been changed in this system as the amount
of crud, goo and muck that came out of it was amazing. Why this was not
done when the new calipers and other brake parts were put in I have no
idea.
Main point of this too long story is be sure to change that fluid as
part of your routine maintenance program.
Welcome back Will, glad you enjoyed your trip.
Best
Mike N
Hugh
glass. Mine has always paid for breakage in full.
Hugh
Robert Carr wrote:
>
> Talk about chipped windshields. Bought my present truck in the spring
> of 1997.
snipped
>
> Although I don't remember ordering the option, I think my truck has an
> object attractor mechanism on it. Been looking for the switch to turn
> it off. Either that or it is all being caused by the fact that I
> raised my deductible to $500 a few years ago.
>
> Bob
>
> On Sat, 26 Aug 2000 03:11:31 GMT, W F Sill <wi...@epix.net> wrote:
>
Robert Carr
My comprehensive has a deductible of $500, used to be $250. I think it
comes down to the insured's choice. Maybe my choice was not the best,
although it worked OK until this truck came along.
Bob
On Sat, 26 Aug 2000 21:19:46 -0400, Hugh <hug...@dreamscape.com>
wrote:
>Hi Bob. Isn't your comprehensive insurance the one that covers the
>glass. Mine has always paid for breakage in full.
>Hugh
>
snipped previous references
Robert Carr
Did a little additional thinking(probably dangerous). As best I can
recall, I don't think I have ever had a seriously chipped or cracked
windshield in 47 years of driving, until now. I had one special case,
when I first came to Calif., in which I got into a sand storm crossing
between Las Vegas and LA. The windshield got so severely pitted that
you could not see out at night with other headlights shining on the
glass. I do remember that glass being covered fully by my
comprehensive, with no deductible. I think as time went on I chose to
reduce my rates by going to or increasing the deductible. Maybe it
follows that old line, "pay me now or pay me later". It's now later.
Bob
On Sun, 27 Aug 2000 03:31:28 GMT, Robert Carr <rac...@home.com>
wrote:
GBinNC
wrote:
><...> that old line, "pay me now or pay me later". It's now later.
It's also later now, right? <g>
Best wishes...
GB in NC
Lon VanOstran
you drive in the mountains.
Lon, who suggest a very large life insurance policy.
First Last
>
> On 8/22/00 >hazen...@webtv.net writes in the middle of a good post on how to
> safely decend mountain grades:
>
> >So here's wacha do : put very light pressure
> >on the brake pedal . Just enough to hold your speed where you want it .
> >KEEP your foot ON the pedal . That's right . RIDE the brakes . LIGHTLY
> >!!! Don't " pump" them . RIDE them. LIGHTLY .
John,
I recently did a trip into Bella Coola in BC (Canada) towing my 26ft
5th wheel with my 86 F250, S/C long box, C6 auto, 4x4, turbo 6.9 diesel
pick up.
Both going in and out one has to negotiate 18% grades with very
severe switchbacks.
I used low range four wheel drive in 1st gear and was able to walk down
at around 8 mph and only touched the brakes twice (momentarily) in about
25km (15 miles). That is the way to go down steep hills - if you have
four wheel drive. The brakes should be left for emergencies.
Hope it helps someone else - worked for me.
John
Sky Walker
=>Hi Will, welcome back
=>
=>I don't disagree at all with your comments. As you know these
=>discussions on descending steep grades invariably become a discussion
=>on continual light braking vs stab. I guess both techniques have been
=>taught to truckers over the years, one method or the other being
=>preferred at selected points in time. Your absolutely correct that we
=>want to minimize the heat build up on brakes. For me that is
=>achievable in two ways. First use gearing (engine braking) to the
=>maximum extent possible and second reduce the downhill speed. The
=>faster you go down the hill while using braking, the higher the rate
=>of heat build up. If the brakes start going away half way down the
=>hill, then pull over and stop and let them cool. In effect this is
=>reducing the average downhill speed.
=>
=>As you know, I tend to look at things in a theoretical manner.
=>Although much simplified, I look at going down a hill as converting
=>potential energy into kinetic energy(speed). If a speed increase is
=>not desired, then braking is applied converting potential energy into
=>heat. Whether a person uses continual light braking or the stab
=>approach, the same amount of potential energy is converted to heat in
=>traveling from the top of the hill to the bottom. However, if the time
=>to travel from top to bottom is increased(lower average speed), then
=>the rate at which this conversion takes place is extended(lower heat
=>input rate). If the heat input rate and heat output(dissapation) rate
=>are suitably balanced(not necessarily equal), the brakes will not
=>overheat and will be there when needed.
=>
=>One final thought. Speaking only for myself, I think it would be
=>easier to sense brake heat build up(fading) using the more
=>moderate/aggressive braking involved in the stab method, rather than
=>the continual light braking technique. I haven't given this a lot of
=>thought, but that is the way it seems to me.
=>
=>Bob
=>
Following your argument, when both method are in braking condition, both
method's heat dissipation surface area are the same.
When both method are not in braking condition, both method's heat dissipation
surface are increased, because all brake surface are exposed(not in contact),
BUT "continual light braking" can NOT not in braking condition. Otherwise it
is not called "continual light braking" method.
In the "continual light braking" method, the surface in contact to generate
heat can not be used for heat dissipation. Since we are in long down hill(if
not, why bother with this discussion), this becomes a big factor to build up
heat(if heat can not be dissipated, it adds up a lot in the long run).
So following your argument, stab method will have cooler brake system.
W F Sill
>I used low range four wheel drive in 1st gear and was able to walk down
>at around 8 mph and only touched the brakes twice (momentarily) in about
>25km (15 miles). That is the way to go down steep hills - if you have
>four wheel drive. The brakes should be left for emergencies.
Thanx for mentioning this. I have brought it up before, and it is
particularly useful for those with automatics descending really steep
grades. Without 4wd low range, it is virtually impossible to keep
speed under control for switchbacks without using the service brakes,
and over-use of same is mighty dangerous. And though it DOES matter
if you choose the stab method or the brain-dead continuous drag
method, if you abuse brakes to failure the only real difference is
that the latter will get you dead a little sooner than the former.
STAY OFF THE BRAKES as much as possible.
W F Sill
>In the "continual light braking" method, the surface in contact to generate
>heat can not be used for heat dissipation. Since we are in long down hill(if
>not, why bother with this discussion), this becomes a big factor to build up
>heat(if heat can not be dissipated, it adds up a lot in the long run).
>
>So following your argument, stab method will have cooler brake system.
I don't disagree, and further point out that the rate of heat
dissipation is hugely affected by delta T -- the difference in
temperature between the hot stuff and the ambient air. The stab
method creates high peak temperatures and dissipates heat faster for
that very reason.
I have not seen any credible detailed analysis of the differences, and
frankly think the whole question boils down to "which way will get ya
killed quicker?" If you ride, stab or feather your brakes enough to
cause failure, you can become a statistic.
Robert Carr
I don't disagree with your comments. However, I suppose someone could
present an argument that you get better heat transfer by conduction
from the shoe or pad to the drum or rotor. Then the larger surface
area of the drum or rotor could more easily lose the heat through
radiation. I, personally, would be hard pressed to prove that point in
a convincing manner.
Best I remember someone told me many years ago, long before RVing
entered my life, that I should not drag my brakes for long periods of
time. To do so, would cause overheating and loss of braking
capability. I presently use the gear down, supplemented by stab
braking, method to descend hills and will continue to do so until
someone can give me a clear cut explanation of why continual braking
is better.
Bob
W F Sill
>The only problem with using 4 wheel drive in a pickup with PART TIME 4 wheel
>drive (the kind where the owners manual warns you about using 4 wheel on dry
>pavement) is that the reasons for not using it on dry pavement will be
>amplified exponentially with the heavy load, low range and going downhill.
>The part time systems cannot be made to perfection and there will always be
>some "driveline windup." The part time systems with the simple gear
>transfer cases count on some minute slippage, tires to road, to correct for
>the system's limitations.
OK, I knew SOMEBODY would bring this up! 8-)
Technically that's at least partly correct, but few 18% grades are
long enough and/or on pavement to present a serious problem. It is
true that prolonged operation on pavement locked in 4wd (those WITHOUT
a center diff or a viscous coupling deal) can cause premature wear and
even failure. At the reduced speeds and rare situations we're
addressing, I feel the risk is minimal, and have done it myself with
no evident ill effects. Why? Because until you do it so long that
the grease gets hot in the differentials, the loads are no worse than
when you pop the clutch in yer driveway. The ONLY failtures I know of
that could be traced to running in 4wd on pavement came about after
many miles of doing it.
I don't personally feel that having a load pushing you makes a huge
difference as you suggest, however. If you are *carrying* extra tons
- yes, but when towing, the tires will slip about as easily as they
do emply.
>I had an idea of leaving the front hubs unlocked and going into low range
>but when I ran that by someone (here, I believe) I was told that would be
>the fastest way to snap an axle. I don't know enough about the system to
>understand why that would be but, unfortunately, I don't believe the 4x4 low
>range method is good for the truck on dry pavement.
Hmmmm. We have done that as well, and the same ideas apply: there is
very little more maximum strain from towing than empty. IMO an axle
so light than it cannot deliver enough torque to spin a tire on
pavement is too fragile to trust at all. So I don't THINK there is
much chance of snapping an axle - and if there is it is no greater or
less regardless of what gear you're in.
The "ideal" setup to cope with this issue of descending really steep
grades is a 2-speed transfer case with a full-time 4wd option. This
divides the loading equally and eliminates the "windup" problem.
Hugh
break the drive axle(s) as long as you aren't trying to accelerate. With
a load on the bed (as with a 5th wheel), you can get enough torque to
snap an axle when trying to speed up. Using low range to keep your speed
down won't generate enough torque to snap anything during a descent.
Hugh
Glenn wrote:
>
> x-no-archive: yes
>
snipped
> I had an idea of leaving the front hubs unlocked and going into low range
> but when I ran that by someone (here, I believe) I was told that would be
> the fastest way to snap an axle. I don't know enough about the system to
> understand why that would be but, unfortunately, I don't believe the 4x4 low
> range method is good for the truck on dry pavement.
>
> Glenn in Den.
snipped
John E. Balch
I sure would like to know how how a down shift would destroy a vacuum
modulator valve. I would say find another mechanic.
John E. Balch
>x-no-archive: yes
>The only problem with using 4 wheel drive in a pickup with PART TIME 4 wheel
>drive (the kind where the owners manual warns you about using 4 wheel on dry
>pavement) is that the reasons for not using it on dry pavement will be
>amplified exponentially with the heavy load, low range and going downhill.
>The part time systems cannot be made to perfection and there will always be
>some "driveline windup." The part time systems with the simple gear
>transfer cases count on some minute slippage, tires to road, to correct for
>the system's limitations.
>I had an idea of leaving the front hubs unlocked and going into low range
>but when I ran that by someone (here, I believe) I was told that would be
>the fastest way to snap an axle. I don't know enough about the system to
>understand why that would be but, unfortunately, I don't believe the 4x4 low
>range method is good for the truck on dry pavement.
>Glenn in Den.
>"W F Sill" <wi...@epix.net> wrote in message
>news:4akkqssdhm4estrad...@4ax.com...
>> Not long ago, First Last <user...@uniserve.com> wrote:
>>
>>
>> >I used low range four wheel drive in 1st gear and was able to walk down
>> >at around 8 mph and only touched the brakes twice (momentarily) in about
>> >25km (15 miles). That is the way to go down steep hills - if you have
>> >four wheel drive. The brakes should be left for emergencies.
>>
>> Thanx for mentioning this. I have brought it up before, and it is
>> particularly useful for those with automatics descending really steep
>> grades. Without 4wd low range, it is virtually impossible to keep
>> speed under control for switchbacks without using the service brakes,
>> and over-use of same is mighty dangerous. And though it DOES matter
>> if you choose the stab method or the brain-dead continuous drag
>> method, if you abuse brakes to failure the only real difference is
>> that the latter will get you dead a little sooner than the former.
>>
>> STAY OFF THE BRAKES as much as possible.
>>
>> Will KD3XR ---- the Curmudgeon of Sill Hill
>> Before flaming, pause. I post to help rv'ers
>> and annoy morons. Whichever shoe fits, wear it.
If the rig can get up the grade in two wheel drive, then I would not worry
about getting down in four wheel with the front hubs unlocked since the
stress on the steel parts would be the same in the differential. With an
excessive load, the gears will go before the axle on a long pull (or push)
on a grade. This can be a problem on a truck say with a half ton rating and
a large engine. If you have a manual transmisison with a compound low and
pop the clutch you can easily break an axle.
John E. Balch
I have no reliable way of knowing the engine speed. On a standard
transmission, I just do not exceed the speed for the up shift recommendaion.
I do not want to over speed the engine so will have to buy a tachometer.
bill horne
>
> Sky
>
> I don't disagree with your comments. However, I suppose someone could
> present an argument that you get better heat transfer by conduction
> from the shoe or pad to the drum or rotor. Then the larger surface
> area of the drum or rotor could more easily lose the heat through
> radiation. I, personally, would be hard pressed to prove that point in
> a convincing manner.
>
> Best I remember someone told me many years ago, long before RVing
> entered my life, that I should not drag my brakes for long periods of
> time. To do so, would cause overheating and loss of braking
> capability. I presently use the gear down, supplemented by stab
> braking, method to descend hills and will continue to do so until
> someone can give me a clear cut explanation of why continual braking
> is better.
>
> Bob
>
I agree, but there may be a definitional problem with 'stab braking'.
The GA Dept of Public Safety defines 'stab braking' as:
"Stab braking. (Only on vehicles without anti-lock brake systems.)
Apply your brakes all the way.
Release brakes when wheels lock up.
As soon as the wheels start rolling, apply the brakes fully again. (It
can take up to one second for the wheels to start rolling after you
release the brakes. If you re-apply the brakes before the wheels start
rolling, the vehicle won't straighten out.)"
http://www.ganet.org/dps/gcdl/5-4.htm
I don't think anyone is recommending that method for going downhill.
That leaves continuous light/moderate braking as opposed to intermittent
light/moderate braking - along with lower gears in both cases.
On which of those should be used for downhilling, the The GA CDL manual:
http://www.ganet.org/dps/gcdl/5-4.htm
has this to say:
"Remember: The use of brakes on a long and/or steep downgrade is only a
supplement to the braking effect of the engine. Once the vehicle is in
the proper low gear, the following is the proper braking technique:
Apply the brakes just hard enough to feel a definite slowdown.
When your speed has been reduced to approximately 5 m.p.h.
below your "safe" speed, release the brakes.
[This brake application should last for about three (3) seconds.] When
your speed has increased to your "safe" speed, repeat steps
1 and 2.
For example, if your "safe" speed is 40 m.p.h., you would not apply the
brakes until your speed reaches 40 m.p.h. You now apply the brakes hard
enough to gradually reduce your speed to 35 m.p.h. and then release the
brakes. Repeat this as often as necessary until you have reached the
end of the downgrade."
More on mountain driving is here:
http://www.ganet.org/dps/gcdl/2-13.htm
Note that the above does not imply that I'm recommending or demanding
that method for everyone. Y'all can evaluate the info and choose your
own method. Myself, I agree with the GA Dept of Public Safety. It's the
way I've always driven in mountains - towing or not towing - and it's
the way I'll continue to drive in mountains until a better
explanation/recommendation comes along - and I don't yet consider
explanations/recommendations on Usenet by ex-largecar drivers
necessarily 'better'.
--
bill
Theory don't mean squat if it don't work.
Robert Carr
I agree with what you said. I use the term "Stab Braking" to
differentiate from continual braking, since those are the terms
others have used. When I mention "Stab Braking" I mean the same as you
described in your final paragraphs. It, more accurately, is a form of
periodic or semi-periodic braking.
Thanks for pointing out the potential for terminology confusion.
Bob
W F Sill
a Georgia publication has the following:
>"Stab braking. (Only on vehicles without anti-lock brake systems.)
>
>Apply your brakes all the way.
>Release brakes when wheels lock up.
>As soon as the wheels start rolling, apply the brakes fully again.
Let the record show that I too have not intended THAT meaning in the
context of descending long steep grades. I prefer to say something
like "intermittent moderate application". Full lock would be absurd
descending grades, and probably everyone is already up to here with my
views on the lunacy of continuous dragging of brakes. In the future I
won't risk confusion by mentioing "stab" braking in this connection.
hazen...@webtv.net
gets misconstrued . Like " How come a purple man has green teeth ?
because he drove his motorcycle in red fire " . I SAID ::::: DROP
YOUR RIG IN A LOWER GEAR . THE ONE YOU'D COME UP THE HILL IN . THEN
LIGHTLY , NOT MODERATELY , RIDE 'EM . You wanna stab em ? go ahead !
When they fade YOU WON"T KNOW IT !!!!!!!!!!!!!!!!!!!!! If you ride
them , you'll FEEL the fade . GEAR DOWN AGAIN !!!!!!!!!!!!!!!!!!!!!!!
If you see or smell brakes , apply light pressure ( it's gonna take
more now because you screwed up !! ) and GET OFF THE ROAD !!!! Quit
overloading your rig . You wana be a big boy , buy a Peterbilt !!!!!!
Go for a ride in a damn truck , Sill . I know you were a safety director
You were not a trucker . If you overload your rig , you are just flat
stupid. WEIGH IT !! Get a brake job . Take an escape ramp . Get
a real life . Haul a load for a company . Get A CDL . Pull over & make
love to momma . When was the last time you did that ???? Good Lord
Good " rope ' , eh ? I always get everyone to hang themselves .
If you still think I don't know my stuff , how come none of you has
quoted from a CDL manual ? I'll bet if you spent more time with your
old lady's in the back of your rig you wouldn't be on here . I don't
have one . I'm a damn hermit . Go make love , not war & stupidiity .
Long John
http://community.webtv.net/hazencajun/JOHNSANTIQUES
Pete Dumbleton
all four wheels engaged in compound low, all the power is applied with
great mechanical advantage to the rear drivetrain with great likelihood of
overstressing something to the point of failure. I guess it wouldn't be
so hot to have your drivetrain come loose just about the time you were
planning to rely on engine braking to slow your truck and trailer...
However, I suspect you'd be more likely to damage something trying to get
over an obstacle or going up rather than coming down a hill, because the
stresses of coming down would be within the design range for any rear
drivetrain. Unless of course you drop it into 4W-Low coming down a grade
at 45 mph and expect not to litter the road with hot, twisted steel...
bill horne
> Good " rope ' , eh ? I always get everyone to hang themselves .
> If you still think I don't know my stuff , how come none of you has
> quoted from a CDL manual ? I'll bet if you spent more time with your
> old lady's in the back of your rig you wouldn't be on here . I don't
> have one . I'm a damn hermit . Go make love , not war & stupidiity .
> Long John
>
> http://community.webtv.net/hazencajun/JOHNSANTIQUES
I have quoted from a CDL manual. Fading brakes must have caused you to
miss it. Here it is again:
The GA CDL manual:
http://www.ganet.org/dps/gcdl/5-4.htm
has this to say:
"Remember: The use of brakes on a long and/or steep downgrade is only a
supplement to the braking effect of the engine. Once the vehicle is in
the proper low gear, the following is the proper braking technique:
Apply the brakes just hard enough to feel a definite slowdown.
When your speed has been reduced to approximately 5 m.p.h.
below your "safe" speed, release the brakes.
[This brake application should last for about three (3) seconds.] When
your speed has increased to your "safe" speed, repeat steps
1 and 2.
For example, if your "safe" speed is 40 m.p.h., you would not apply the
brakes until your speed reaches 40 m.p.h. You now apply the brakes hard
enough to gradually reduce your speed to 35 m.p.h. and then release the
brakes. Repeat this as often as necessary until you have reached the
end of the downgrade."
--
dixie...@pbtcomm.net
downhill with my PU and TT, but let's review my options. I've got an
automatic tranny, I leave the overdrive off, normally I pull in 3rd
gear. So, when I come to a steep grade, would it be OK for me to
shift into 2nd and then if I see that my speed is too great and I need
to gear down, CAN I THEN SAFELY DROP IT FROM 2ND TO 1ST GEAR?
On Tue, 22 Aug 2000 16:02:47 -0700 (PDT), hazen...@webtv.net wrote:
>I'm writing this article for new drivers who may have graduated to a
>sizeable RV. I'm an ex- trucker with many years of experience hauling
>oversize loads in the Sieara Nevada mountains . Unfortunately , when you
>purchase or rent a big RV it does not come with instructions so I'm
>going to give you some free tips on one of the most dangerous parts of
>driving : coming off a long hill.
> First , let's talk about loading . Since you probably have never
>weighed your rig when she's loaded , you might be unpleasantly surprised
>that she's OVERLOADED ! The GVW ( gross vehicle weight ) should not be
>exceeded . Any truck stop will gladly weigh your rig ( about five bucks
>) . If you are overloaded you are exceeding your braking capacity . In
>the event of a serious accident , what's left of your rig will be
>weighed . If you've exceeded the GVW , you may well be found at fault
>in the wreck . Not good . Don't over load her .
> Now , as you aproach the downdrade , size up the situation . How
>steep is it . 6% is steep . anything over that is very steep . How long
>is the grade ? More than a mile is getting serious . If there are signs
>warning big trucks about the grade , you heed them too . You ARE a big
>truck . So here's watcha do : select the gear that you know you
>would come UP the hill in . If you have an automatic , ( most now are 4
>speeds ) it probably would come up a steep hill ( 6%) in second gear .
>If it's a very steep hill , drop her in first . Do all this BEFORE you
>start down & be going slow enough that you don't over-rev the engine .
>Slow down now , not later . If traffic is behind you , ( especially big
>trucks ) , pull over & let 'um by . We're RVin' , not in a hurry
>remember ? We're never in a hurry . If you are , you chose the wrong
>hobby . OK start off the grade . If the engine holds you back , great
>, but it probably won't . So here's wacha do : put very light pressure
>on the brake pedal . Just enough to hold your speed where you want it .
>KEEP your foot ON the pedal . That's right . RIDE the brakes . LIGHTLY
>!!! Don't " pump" them . RIDE them. LIGHTLY . If light pressure does
>not hold you back , increase the pressure GRADUALLY and select a lower
>gear. Bring your engine RPM's down so it will not over - rev the engine
>as you drop a gear . Now you should be able to decrease pedal pressure .
>Do not be tempted to go faster because you have traffic behind you . If
>there is a GOOD , SAFE spot to pull over and you know the grade will
>continue , pull over . Be courteous . Stay there a while , like 15
>minutes . Give the " brakes a break " . Let 'em cool off . Go make a
>sandwich or make love with momma ( hopefully that takes more than 15
>minutes :-). We ain't in a hurry .
> As you see the bottom of the hill , go ahead & gear back up & coast
> MAKE SURE it's the bottom . Donner Pass is very decieving . Just about
>the time you think you're there , you ain't .However , use flat spots &
>up grades to cool your brakes .
> Now , a little warning : Big trucks cannot stop AT ALL when their
>brakes are hot . On occaision , a rooky trucker can lose his " binders "
> If you see a big rig barreling up on you on a steep downgrade , he may
>have lost control . He may also just be an idiot or as Reddog puts it ,
>an " ARB " ( good name Bill ) . If possible get to the right . If he
>rear-ends you , it's over . A good indicator of a bad hill is the odor
>of hot brakes . Once you've smelled it , you never forget it . Actually
>hurts your nose . This means you're on a bad - ass hill & trucks
>frequent it . Watch your mirrors . Don't be bullied in to going faster
>by a trucker . If he tailgates you , pull over IF you can . If not ,
>try to ignore him . When he passes , turn him in . I hate to say it but
>on a reply to one of my recent posts , a guy spoke of having truckers
>busted by using his cell phone & exaggerating the problem by telling the
>police dispatcher that he thought he might be drinking . Tailgating is
>deadly and if it takes that drastic a measure to stop it , well so be it
> Alot of truckers will read this . I'll get bitched at . Well , don't
>tailgate & ya won't have a problem , will ya ? I'm pro - truck because
>they get our "stuff" to us . EVERYTHING . But I'm dead set against
>rotten drivers of ALL vehicles , ESPECIALLY trucks because they are very
>deadly. Don't worry Bill & Lon , I won't have one of my little " truck
>tantrums " .
> I think I covered it but main thing I'm trying to do on this NG is
>help us all stay alive . I've taken alot of flak from it & think I
>helped a few folks . Met some real cool people on here too . What I
>taught you today is the professional way to come down a hill . Mr two
>million mile man. In a large car . Y'all be safe . Enjoy the ride .
>Smile & wave .
> One last thing . If you don't have a CB radio , get one , When a
>trucker loses his brakes he generally starts screaming on the radio .
>Channel 19 . If you hear it , get off the road if possible . It also
>is a great way to find out how serious the grade is going to be . Have
>some fun . Help others out . Be nice . It will come back on ya' .
>Long John
>
>http://community.webtv.net/hazencajun/JOHNSANTIQUES
>
Vince Wirth
>I've appreciated all of the input on what I should do when coming
>downhill with my PU and TT, but let's review my options.
>AN I THEN SAFELY DROP IT FROM 2ND TO 1ST GEAR?
Dixie,
Most automatic transmissions will NOT drop to first gear because
of the vehicle speed. (over rev the engine). You need to come to a
stop or almost so before it will drop to first. The use of first gear is
not needed most of the time. I can think of only three of four times
that I have needed to use it with my old motor home.
Vince Wirth
http://home.earthlink.net/~vincewirth
W F Sill
>As usual , my original post gets great compliments & then like a joke ,
>gets misconstrued . Like " How come a purple man has green teeth ?
>because he drove his motorcycle in red fire " . I SAID ::::: DROP
>YOUR RIG IN A LOWER GEAR . THE ONE YOU'D COME UP THE HILL IN . THEN
>LIGHTLY , NOT MODERATELY , RIDE 'EM . You wanna stab em ? go ahead !
>When they fade YOU WON"T KNOW IT !!!!!!!!!!!!!!!!!!!!! If you ride
>them , you'll FEEL the fade . GEAR DOWN AGAIN !!!!!!!!!!!!!!!!!!!!!!!
> If you see or smell brakes , apply light pressure ( it's gonna take
>more now because you screwed up !! ) and GET OFF THE ROAD !!!! Quit
>overloading your rig . You wana be a big boy , buy a Peterbilt !!!!!!
>Go for a ride in a damn truck , Sill . I know you were a safety director
> You were not a trucker . . . . . .snipped.
WHOA! Siddown, relax, take some deep breaths, and then READ what has
been written on this topic. 95% of what you've said is OK. Don't get
yer knickers in a knot over one little detail. If you still think you
want to ride the brakes on a long steep grade instead of the tactics
that I and others have suggested, please feel free to do so.
But no matter how well you think it works on your truck, riding the
brakes is a foolish, dangerous technique for virtually all rv's.
Your expertise as a trucker is frankly not relevant on this particular
issue. Sorry you feel you've been attacked, but in fact you've been
supported on most of what you've written - especially on gearing down
and slowing down.
Nash
> On Tue, 29 Aug 2000 12:48:56 GMT, dixie...@pbtcomm.net wrote:
>>I've appreciated all of the input on what I should do when coming
>>downhill with my PU and TT, but let's review my options.
>>AN I THEN SAFELY DROP IT FROM 2ND TO 1ST GEAR?
> Most automatic transmissions will NOT drop to first gear because
> of the vehicle speed. (over rev the engine).
Here in California, there are a number of grades that are 8 to 10
percent that I normally decend in 1st gear. Both my motorhome
and pickup truck are Fords, they will not downshift into 1st until
I slow below 20MPH. With the gearing I have, 25MPH is 3,000 rpm
which is a safe engine speed for decending long grades in both
the truck and MH.
My truck is a F150 with the AOD and 302 V8. I tow a horse trailer thru
the mountains that weighs about 6,000 lbs loaded. I've had the truck
15 years (150,000 miles) and still have the original tranny, engine,
brake rotors and drums. The MH is a 23 foot Fleetwood Jamboree with
the Ford 460 V8.
--
_ ___,;;;/ | Ron Nash (na...@sdsu.edu) San Diego State University
,;( )__, )~\| |
;; // '--; | Gin-N-Tonic endurance horse
' ;\ | | Luv on Fire trusty trail horse
Robert Carr
If you wish to drop down to a lower gear, in order to take advantage
of additional engine braking, then first use your brakes to slow down
to a speed that is acceptable for that particular lower gear. For
example: I know that in 1rst gear my truck will run 35mph at 3500 rpm.
I don't choose to go above 3500 rpm. Therefore I will use my brakes to
slow to a speed of 30 to 35 mph before downshifting to 1rst gear. A
similar situation occurs when downshifting from 3rd to 2nd. I know
that 2nd gear produces a speed of approximately 55 mph at 3500rpm. I
will use my brakes to slow to a speed of 45 to 50 mph before shifting
to 2nd.
Bob
On Tue, 29 Aug 2000 12:48:56 GMT, dixie...@pbtcomm.net wrote:
>I've appreciated all of the input on what I should do when coming
>downhill with my PU and TT, but let's review my options. I've got an
>automatic tranny, I leave the overdrive off, normally I pull in 3rd
>gear. So, when I come to a steep grade, would it be OK for me to
>shift into 2nd and then if I see that my speed is too great and I need
>to gear down, CAN I THEN SAFELY DROP IT FROM 2ND TO 1ST GEAR?
>
snipped previous reference
Ian Burton
>Apply the brakes just hard enough to feel a definite slowdown.
>When your speed has been reduced to approximately 5 m.p.h.
>below your "safe" speed, release the brakes.
>[This brake application should last for about three (3) seconds.] When
>your speed has increased to your "safe" speed, repeat steps
>1 and 2.
snip
>bill
>Theory don't mean squat if it don't work.
Now I can add to this with some conviction based on real experience.
Driving my F250 with truck camper (1100 lbs UNDER GVW) 2 weeks ago in
Manning Park in BC, descending from the subalpine, I developed/
noticed a knocking sound in the front end when going over the
washboard. Visual inspection under the front showed nothing loose and
noticed that light brake pressure stopped the knock. Being aware of
brake fade etc (so I thought) I left the tranny in low and crept down
the long grade behind a motorhome applying a very light pressure to
the brake pedal. The descent was fine, with no sign of brake fade or
even smell for that matter. When at the bottom, I stopped at the stop
sign for about 20 seconds with foot on brake, crossed the highway and
went to step on the brakes on the other side for the corner to the
campsite. Nothing! The pedal went right to the floor.
After letting the brakes cool, and obviously, the fluid recondense, I
removed the wheel and found that the knocking was a slightly loose
caliper due to wear in the hardware. Stopped at next brake shop and
had the caliper retainers replaced.
Don't ride the brakes.
Ian
Hugh
transmission will shift to second and when speed drops enough, it will
shift to low. One problem I haven't seen mentioned yet is, if you are in
low range and the engine over speeds, the transmission will upshift to
second.
Hugh
W F Sill
>. . . So, when I come to a steep grade, would it be OK for me to
>shift into 2nd and then if I see that my speed is too great and I need
>to gear down, CAN I THEN SAFELY DROP IT FROM 2ND TO 1ST GEAR?
YES, in fact I recommend it highly.
BUT, don't try it going too fast. And do NOT wait until you are going
too fast to do anything right! Some trannies (most?) simply won't
shift down until you slow to a certain preset speed, and even if yours
does you need to avoid overspeeding the engine. You really ought start
very slowly down those steep grades - especially unfamiliar ones.
Pete Dumbleton
owner's manual carefully, that dropping the auto trans-axle into 2
*blocks* it from downshifting to 1... Choices were D (actually
overdrive), 3 and 2. No 1, and no way to force it to 1.
Told another Saturn driver about this. He was skeptical and couldn't find
it, until we both looked it up in his manual.
Do your homework...
Robert Carr
You may drop the lever into low range at any speed you want(assuming
your vehicle has some over speed protection mechanism), but the
transmission may never shift to low. If the downgrade is sufficient,
no higher gear (even second) will slow you enough to allow the
transmission to actually shift into 1rst. You may actually have to use
brakes before the desired gear is obtained. I choose not to rely on
the over speed protection mechanism, and therefore slow to a speed
acceptable for the desired gear change.
Bob
On Tue, 29 Aug 2000 13:26:55 -0400, Hugh <hug...@dreamscape.com>
wrote:
>You can drop the lever into low range at any speed you want, the
>transmission will shift to second and when speed drops enough, it will
>shift to low. One problem I haven't seen mentioned yet is, if you are in
>low range and the engine over speeds, the transmission will upshift to
>second.
>Hugh
>
snipped previous reference
Hugh
the group. I should have been more explicit in my answer. Naturally the
brakes need to be applied as well as downshifting. I was referring to
placement of the shift lever in low. If done with the intent of
maintaining a speed downhill, if the engine overspeeds, the transmission
will shift to next higher gear. This would be a real shock to the driver
if he was expecting his speed to remain in a safe range. If the grade
forced the shift change and his brakes were already at the marginal
stage, he'd have a "fun" ride.
Hugh
Robert Carr wrote:
>
> Hugh
>
> You may drop the lever into low range at any speed you want(assuming
> your vehicle has some over speed protection mechanism), but the
> transmission may never shift to low. If the downgrade is sufficient,
> no higher gear (even second) will slow you enough to allow the
> transmission to actually shift into 1rst. You may actually have to use
> brakes before the desired gear is obtained. I choose not to rely on
> the over speed protection mechanism, and therefore slow to a speed
> acceptable for the desired gear change.
>
> Bob
snipped
Hugh
Hugh
Vince Wirth
> if the engine overspeeds, the transmission
>will shift to next higher gear.
Hugh,
With my C6 it will Not shift up if the lever is in first gear. I have
to watch the RPM's and add some brake when it exceeds 4000 RPM.
Vince
Hugh
Thanks for setting me straight.
Hugh
Robert Carr
I'm kind of getting the impression that all automatics may not
provide for controlling the actual transmission downshift from 2nd to
1rst as a function of speed. I know that my GMC owners manual says
that if the speed is too high, it will not downshift. Unfortunately
they never tell me what that speed is and I have never established
what it is. Someone, earlier in this thread, mentioned that he had two
Ford products that would not shift down unless the speed was below
20mph. I know mine will shift down at 30 to 35mph. So even if the
vehicles have this provision, it may vary all over the place as far as
what speed it will occur at. Guess each owner needs to establish some
knowledge of what speed is appropriate for downshift, especially if
they are depending on that gear for safe downhill travel. Guess we are
really getting down to basics here. Amazing how these threads develop,
all the way from braking technique to how to shift your transmission.
Bob
On Tue, 29 Aug 2000 16:59:54 -0400, Hugh <hug...@dreamscape.com>
wrote:
AJKing554
hazen...@webtv.net to listen:
>WHOA! Siddown, relax, take some deep breaths, and then READ what has
>been written on this topic.
Will, one of the things you got to miss (unless went back and read them) was
being told at least three times a day to "STAY THE HELL AWAY FROM BIG TRUCKS"
by this stream of consciousness know it all. Now he has come up with a new
"lesson" for us, "HOW TO DESCEND GRADES", and I wonder how long he'll beat this
one to death.
Alan
ajki...@aol.com
bill horne
And he gets really hurt and pissed if you drift off his chosen rant, so
try to show a little compassion here, particularly if you're a
politically correct Democrat - walk the talk and maintain the thread.
--
bill horne
>
> Hugh
>
> I'm kind of getting the impression that all automatics may not
> provide for controlling the actual transmission downshift from 2nd to
> 1rst as a function of speed. I know that my GMC owners manual says
> that if the speed is too high, it will not downshift. Unfortunately
> they never tell me what that speed is and I have never established
> what it is. Someone, earlier in this thread, mentioned that he had two
> Ford products that would not shift down unless the speed was below
> 20mph. I know mine will shift down at 30 to 35mph. So even if the
> vehicles have this provision, it may vary all over the place as far as
> what speed it will occur at. Guess each owner needs to establish some
> knowledge of what speed is appropriate for downshift, especially if
> they are depending on that gear for safe downhill travel. Guess we are
> really getting down to basics here. Amazing how these threads develop,
> all the way from braking technique to how to shift your transmission.
>
> Bob
>
I think the impression you should be getting is that all transmissions
are not created equal, and that general statements are not to be
trusted.
I can speak with authority about My 96 Chevy PU 4L60-E with the 5.7L
engine, but for no other model, make, year, or engine/trans/diff
combination. I can't even speak for the same thing owned by someone
else.
So, if I start from a standing start with the selector in 2nd, the
vehicle starts in 2nd - not 1st.
If I start from a standing start in 1st, the thing upshifts to 2nd all
by itself at 28 mph (at moderate throttle).
If I'm in 2nd, and above 28 mph, and select 1st, it will not downshift
to 1st until speed reaches 28 mph or less.
At one point in all this stuff, I managed to accelerate in 1st to 40
mph. What shift sequence and/or throttle depression allowed this, I
don't know.
At any rate, if you want to know what your specific vehicle does under
specific conditions, you need to test your specific vehicle under your
specific conditions. Anything else is likely to be theoretical dogshit
which may or may not apply to you and your vehicle under certain
specific conditions.
The bottom line is TEST Your vehicle under Your conditions, and then
you'll KNOW. And theory still don't mean squat if it don't work.
Jon Porter
>The answer to this question is quite simple, in my opinion.
>
>If you wish to drop down to a lower gear, in order to take advantage
>of additional engine braking, then first use your brakes to slow down
>to a speed that is acceptable for that particular lower gear. For
>example: I know that in 1rst gear my truck will run 35mph at 3500 rpm.
>I don't choose to go above 3500 rpm. Therefore I will use my brakes to
>slow to a speed of 30 to 35 mph before downshifting to 1rst gear. A
>similar situation occurs when downshifting from 3rd to 2nd. I know
>that 2nd gear produces a speed of approximately 55 mph at 3500rpm. I
>will use my brakes to slow to a speed of 45 to 50 mph before shifting
>to 2nd.
>
downshift above the rated speeds. Auto transmissions in the last couple of
decades have been designed with a lockout feature that prevents a forced
downshift if the speed is too great for it. I've had that happen to me. The
tranny stayed in it's present gear range until the vehicle slowed down
enough for it to downshift. I think that many manual transmission have a
similar feature as well.
Jon Porter
>In 1979 or 80 I was able to buy and install a kit in my C6 transmission
that
>would allow manual shifting to any gear. Is such a kit still available? I
>think it came from John Geraty in Southern California. He was writing for
>Trailer Life and operating a shop at that time.
B&M still makes such kits. Check out a local Performance shop to get one, or
try the catalogs (ie: JC Whitney )
Jon Porter
<39abae60...@nntp.pbtcomm.net>...
>I've appreciated all of the input on what I should do when coming
>downhill with my PU and TT, but let's review my options. I've got an
>automatic tranny, I leave the overdrive off, normally I pull in 3rd
>gear. So, when I come to a steep grade, would it be OK for me to
>shift into 2nd and then if I see that my speed is too great and I need
>to gear down, CAN I THEN SAFELY DROP IT FROM 2ND TO 1ST GEAR?
>
It depends some on the transmission and how fast you are going. The manual
for the chassis of the m'home should tell you what the speed range is for
the various gear ranges. My experience has been that I can safely get the
auto-transmission to downshift into a lower gear as long as I'm not above
the top speed rated for that gear setting. In cars, often as high as 30 mph
for the L speed.
However, a forced downshift such as this is hard on the clutches in the
auto-transmission. You'll be fine doing it once in a while as needed, but if
used as a brake to slow down the vehicle from a higher speed you'll shorten
the life of the transmission. If you are above the normal 1 - 2 upshift
point for the transmission (typically about 15 mph) then that's too fast and
there will be a definite high-rev response from the engine. The engine can
take it, but it strains all the parts of the whole drive train.
I have done a high speed downshift in cars in the past when I was scared
enough to do so. Avoided accidents that way, although it's hard on the whole
drive train. I figure that's better than the possible results of a
collision!
Best way to do it is to use the brakes until you have slowed enough to
safely shift down into the range you want.
I used to drive school busses for a while. Had a fellow driver who was
approaching a stop light at an intersection at about 45 mph when his brakes
failed completely. He took the standard tranny from 4th to first. It stopped
the bus, but blew out the tranny onto the roadway. Somebody else had to come
pick up the kids at that intersection and finish the route for him.
Oh, one other thought on this topic - There is a major difference in braking
systems between trucks and m'homes. Trucks use air brakes while most m'homes
use hydraulic brakes. You can boil the fluid in a hydraulic system. Trucks
don't have that problem because, well, it's an air pressure system. Note
that many Class A m'homes use air brakes as well.
Bldrbuck
Bldrbuck
new fluid put in.
Robert Carr
I don't disagree with the final conclusion on testing your own vehicle
under your own conditions. I also understand your signature line, but
I don't think I have seen any theory in this segment of the thread
related to down-shifting. I have, however, seen a reasonable amount of
opinion on the subject. Some of these opinions are likely based on
experimental fact(a specific vehicle under a specific condition), but
not theoretical dogshit. From these opinions it seems reasonable to
conclude, as you apparently did, that a little testing is in order to
insure that a lower gear is entered when required. That is probably
the best general conclusion that can be drawn from these discussions,
at least for now. That is why I stated "Guess each owner needs to
establish some knowledge of what speed is appropriate for downshift,
especially if they are depending on that gear for safe downhill
travel".
Just my opinion
Bob
bill horne
>
> Bill
>
> I don't disagree with the final conclusion on testing your own vehicle
> under your own conditions. I also understand your signature line, but
> I don't think I have seen any theory in this segment of the thread
> related to down-shifting. I have, however, seen a reasonable amount of
> opinion on the subject. Some of these opinions are likely based on
> experimental fact(a specific vehicle under a specific condition), but
> not theoretical dogshit.
Ok, I'll concede that I may have unjustifiably overenthused a bit there,
and I retract 'theoretical dogshit'. I think I may be developing a
kneeje...ummm...conditioned response that I'm going to have to work on
unconditioning.
> From these opinions it seems reasonable to
> conclude, as you apparently did, that a little testing is in order to
> insure that a lower gear is entered when required. That is probably
> the best general conclusion that can be drawn from these discussions,
> at least for now. That is why I stated "Guess each owner needs to
> establish some knowledge of what speed is appropriate for downshift,
> especially if they are depending on that gear for safe downhill
> travel".
>
> Just my opinion
>
> Bob
--
bill
Theory don't mean squat if it don't work.
hazen...@webtv.net
to want to initiate a good one. Does it not seem strange a " newbie "
from " webtv" takes stage ? All I want to do is help . Not argue . I'll
argue but not
if it is over something a scientist can't decide like " brake ride " or
" brake stab" . Please remember I no longer drive 18-wheelers. I'm an
RVer like you who now has an antique shop. I'm not up on the technology.
I never proclaimed to know it all . I just wanted to help new folks .
Especially those with big machines . I want all of us to enjoy this
experience my folks introduced me to in the 50's. Now , it is not as fun
,by far. You tell me it ain't ( SP ) . We were lucky to see free
camping , helpful safe truckers , cool cops , and so on . That shit is
over , my friend . We used to DRINK out of roadside streams . If you
broke down , someone stopped ; helped you . I'm sorry as hell if I
remind you of those days because they DID exist. I had no kids , prefer
being a hermit because I like living in the past . I try to give you all
a taste of it but it's gone . Most of you on here are about my age ( 50
) & you missed even that because I spent my childhood in rural Nevada .
I'm sorry you couldn't share that with me . Bill , Lon , Mark , Jim , ;
you know who you are . I'm glad I met you but saddened life changed. I
just try to make it better but the " chemult " gets me going . Nevada
is still real mellow in the NE section. VERY lonely. That's why I'm
here & I surely invite you . John
http://community.webtv.net/hazencajun/JOHNSANTIQUES
bill horne
>
> Yes, I get upset at a stray from a topic I create . You guys don't seem
> to want to initiate a good one. Does it not seem strange a " newbie "
> from " webtv" takes stage ? All I want to do is help . Not argue . I'll
> argue but not
> if it is over something a scientist can't decide like " brake ride " or
> " brake stab" .
I think we're already past 'stab', but the main issue is still being
argued - How to go downhill? Continuous light braking (riding the brakes
all the way down), or periodic 'just hard enough' braking?
In another post, you asked for a CDL quote, and I've posted it twice.
The GA CDL describes periodic application of brakes - not the continuous
application you recommend.
So the questions become -
Are you right and the GA CDL wrong? Or,
Is your method an old method which has been superceded? Or,
Do current CDL manuals for numerous other States recommend continuous
application? (Which could mean that both methods are being currently
advocated by various official State entities)
> Please remember I no longer drive 18-wheelers. I'm an
Yes, I remembered that. It's why I ask if it's possible that your method
of continuous braking has been replaced by the method in the GA CDL. I'm
an ex-Boy Scout. When I was one, cut/suck and a constricting band was
the recommended first treatment for snakebite. That's no longer true.
Times change, things change. Has downhill braking maybe also changed?
> John
>
> http://community.webtv.net/hazencajun/JOHNSANTIQUES
can...@dtgnet.com
>On 8/29/00 > W F Sill wi...@epix.net writes in the futile cause of getting
>hazen...@webtv.net to listen:
>
>>WHOA! Siddown, relax, take some deep breaths, and then READ what has
>>been written on this topic.
>
>Will, one of the things you got to miss (unless went back and read them) was
>being told at least three times a day to "STAY THE HELL AWAY FROM BIG TRUCKS"
>by this stream of consciousness know it all. Now he has come up with a new
>"lesson" for us, "HOW TO DESCEND GRADES", and I wonder how long he'll beat this
>one to death.
>
>Alan
>ajki...@aol.com
Would be interesting to know how many times you've brought a megaton
vehicle down a steep grade, as compared to haz. The person who has
been there/done that generally knows more than the person with an
opinion, particularly when that opinion is not based on actual
experience.
Besides, everyone knows how to descend a steep grade:
Slowly.
Canoli
Robert Carr
determine if some don't know it or they know it but don't apply it. Of
course, maybe it is only some of the Southern Californians that don't
get it<g>.
Bob
On Wed, 30 Aug 2000 09:26:18 -0700, can...@dtgnet.com wrote:
snipped a bunch
First Last
>
> Slowly.
>
> Canoli
Yes, but there are a lot that don't. These are the problem.
John
John E. Balch
I think the best way is to find the lower gear that lets you get down the
grade with almost no breaking. If you have ever had breaks fade almost
completely away, you know what an upsetting feeling that is, almost not
being able to stop and in a runaway situation. I remember reading years ago
that on a normal car, breaks could take 1000 horse power for a short time,
but if it were constant, it would drop to 10 horse power. This would have
been for drum breaks, which is what most RVs use on the rear wheels where
most of the breaking power comes from. If you have a really long grade to
go down, just be very careful not to overheat those breaks because this is
your life and the others on the road ahead of you. Why take out some young
family and yourself because you want to get to the bottom of the hill ten
minutes faster than you should have.
John E. Balch
Gear down low enough so you need breaks only for the sharp corners and you
will be safe, but also it will save on break repair bills which can be
substantial. Think of the time it takes to make the money to pay for the
break repair job compared to the time you save coming down a grade faster
than the engine can break the rig. Thinking this way, you will be way ahead
time wise if you go slower.
Dick
from the west. It gets a lot of use by truckers who do not heed the
dozen or so warning signs that preceed it. "Truckers, it is not over
yet. There are six more miles of 6% grade. Stay in low gear" etc.
etc. It is followed by "Dead Man's curve". It maintains it's name on
at least a yearly basis. Coming down the hill the smell of burning
brakes is always there.
bill horne
I think you've missed the point. No one in their right mind is
recommending Not downshifting for downhilling. The issue is that when
downshifting is not enough - and it frequently is not - is it better to
ride the brakes all the way down, or to use them periodically. What's
your position on that, and why?
And what's a 'young family' got to do with it. Are old or middle-aged
individuals less important? If 'young family' is supposed to provide
better justification through emotion, then you should go all the way,
and use 'a cute little girl and her cute little kitten'. That will
obscure logic and prevent rational thinking much better than 'young
family'. I think it even works better than, "If it'll save just one
innocent life..."
Gary - KJ6Q
but accurate!
--
Gary - KJ6Q
====================
The fable,"The grasshopper & the ant", reveals the
existance of socialist attitudes - even in Greek times...
"Play today - live off your neighbor tomorrow..."
"bill horne" <red...@rye.net> wrote in message
news:39AD7356...@rye.net...
> "John E. Balch" wrote:
> >
<<SNIP>>