Should a person shift down on a mountain pass? - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 05-09-2005, 12:05 AM   #11
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It doesn't hurt to use the lower gears in the trans to go down a steep grade. That'* why they're there.

Steve, kinda wrong on how a diesel works. What makes the car slow down (gas engine) is when there'* no throttle input the TB plate is closed, and when the engines running up in RPMS with no throttle, it'* trying to suck all the air it wants into the engine but is being restricted by the TB plate. In turn making the compression of the engine slow the car down.

On A diesel.....They don't have a TB plate in the intake, so they can get all the air they want. So when you down shift the only way it really slows down the truck is with the service brakes, hitting the rev governer, or a Jake Brake.

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Old 05-09-2005, 01:11 AM   #12
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Dropping a gear is good on high gradient decents, it does save your brakes. Just remember to put it back in.

Don't shift like a manual though all the time. Completely differen't and pointless.
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Old 05-09-2005, 01:38 AM   #13
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I wouldnt use first, i would down shift from D to 3rd or maybe gradually into second, holding the brakes will make them "fade" just like ssesc said, and my dad being a truck driver as well knows that well to.
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Old 05-09-2005, 02:06 AM   #14
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My dad was a truck driver before he went to school to be a physican and has given me the whole "always use first gear" talk many times.

I aggree on a RWD automatic and any car/truck with a stick.


But I was not entirely sure about the 4t60e and 4t60 tranies since they dont seem to hold up as well as RWD cars.


We are talking rocky mountains here....lots of steep "hills" sorta speak, 12% and 15% grade signs are not uncommon


I just thought that these trannies would not like being at 35mph in 1st gear for 25 minutes or so

Also I meant hitting the brakes hard every so often..when I say ride the brakes. but hitting them failry hard to get down to 20mph or so then going back to 60 and then getting back down to 20.
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Old 05-09-2005, 03:26 AM   #15
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I agree with above- its OK to use if used correctly

HOWEVER- i found out something te hard way

do NOT use downshifting on steep wet roads that are bumpy.

My car started doing the jig down a hill cause the diff wasnt allowing for an even slowing force to the wheels and my back end was getting light. I got half way down hit an unevenly raised bump, back end was light enough to send me all the way around. it was NOT pretty facing back up the hill i just came down.

Moral of the story:
Get a bigger system in teh trunk

OR

Use brakes more when wet and bumpy
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Old 05-09-2005, 09:31 AM   #16
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id say just put your flashers on and use the first or second geear going down the grade and keep it under 35mph. less brake fade and less wear on motor from keeping the RPM'* down
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Old 05-09-2005, 09:31 AM   #17
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id say just put your flashers on and use the first or second geear going down the grade and keep it under 35mph. less brake fade and less wear on motor from keeping the RPM'* down
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Old 05-09-2005, 09:37 AM   #18
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Could also just use "threshold braking" also. Find your target speed for the hill....For example you don't wanna go faster than 45 MPH down the hill.....Start down the hill......let the ve3hicle coast up to 50 MPH and then step on the brake quickly but firmly to get your sped down to your thresh hold again. Good for everyone......
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Old 05-09-2005, 10:38 AM   #19
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when i downshift my truck to slow down while going downhill i hate it... just cant justify putting two tons solely on my transmission...
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Old 05-09-2005, 10:43 AM   #20
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Straight from the 1998 Owner'* Manual...

Quote:
Know how to go down hills. The most important
thing to know is this: let your engine do some of the
slowing down. Shiftt o a lower gear when you go
down a steep or long hill.
Quote:
A CAUTION:
If you don’t shift down, your brakes could
get so hot that they wouldn’t work well. You
would then have poor braking or even none going
down a hill. You could crash. Shift down to let
your engine assist your brakes on a steep
downhill slope
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