I own an 04 sierra 3.5L truck. On steep grades down hill I sometimes brake until I can shift to a lower gear. Is this hard on the transmission? I recently had to rebuild the trans. It would shift from first to second and free wheel into third with no power.
using the engine as a brake on a down hill steep grade with trailer (6000 lb)
- Thread starter asgreig
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HappyWanderer
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The proper way is to downshift before starting down the hill. The rule of thumb is to go down the hill in the same gear that would be needed to climb the same grade.
When speed needs to be reduced, apply the brakes firmly until speed is reduced 5 to 10 MPH and then release. Repeat as necessary. This is called stab braking, which is a technique used to prevent overheating the brakes. Do not ride the brakes, and don't wait until you're going too fast before downshifting.
When speed needs to be reduced, apply the brakes firmly until speed is reduced 5 to 10 MPH and then release. Repeat as necessary. This is called stab braking, which is a technique used to prevent overheating the brakes. Do not ride the brakes, and don't wait until you're going too fast before downshifting.
AStravelers
Well-known member
I don't believe using engine braking is any harder on the transmission than any other use you experience in normal driving. On the other hand if you don't use engine braking and your brakes fade from overheating on a long down hill, you could loose the truck, trailer, and more importantly your life.asgreig said:
As far as wear and damage, a 6000 pound trailer being pulled by a 3.5 liter engine is really working the engine and transmission very, very hard. I would be surprised if your truck was not a max load or maybe overloaded with a 6000 lb trailer.
If you havn't weighed your rig, I recommend you stop in at a CAT truck scale and weigh the rig.
Gary RV_Wizard
Site Team
It's near impossible to damage a modern tranny by manually shifting - it simply will not shift until it is mechanically safe to do so. Shifting at the max acceptable rpms is probably a bit harder than normal shifting, but still within its capabilities. I serious doubt if transmission braking had anything to do with your rebuild.
Wanderer gave excellent advice on braking technique. If you reduce speed and downshift at the top of the hill, you won't have to brake & downshift on the down grade.
Wanderer gave excellent advice on braking technique. If you reduce speed and downshift at the top of the hill, you won't have to brake & downshift on the down grade.
John From Detroit
Well-known member
AStravelers said:
I have had people INSIST that use of the engine brake (Grade brake on an ALLISON) caused early Tranny Failure...
That said. I fully agree with AAStravlers.. with one special case exception the engine can not brake harder than it powers... and if you hit that exception... Well a new 8.1L Vortec last time I checked sold for 7,000 dollars and diesels are more expensive and you are gonna need one (Sized engine is the exception).
Plus installation.
I do not believe the transmission will be over stressed.
However if YOU downshift manually. Do it at the top of the hill before you start down. Same as I do in many RV parks where I want to stay under 5-10-15-20 MPH and well even the car, in LOW, all by itself, goes faster at full idle down a hill (I know, tested the theory last night and on one hill I topped and downshifted at 10mph, 25, in LOW by the time I hit bottom)
I believe you meant 5.3 engine, not 3.5.
Keep trailer brake use to a minimum by using your gears.
The so-called stab braking was taught to truckers that use air brake systems. Those trucks have air valves that might not all work exactly the same and using the brakes lightly might result in some wheels doing nothing. If you repeatedly apply the brakes hard, nothing good will happen, just keep the braking to a minimum.
Keep trailer brake use to a minimum by using your gears.
The so-called stab braking was taught to truckers that use air brake systems. Those trucks have air valves that might not all work exactly the same and using the brakes lightly might result in some wheels doing nothing. If you repeatedly apply the brakes hard, nothing good will happen, just keep the braking to a minimum.
sc4668
Well-known member
My Ford F250 HD has a tow mode button and it does use the transmission to automatically down shift when going down a hill and it works great.
Old Blevins
Well-known member
Good point. Asgreig, does your Sierra not have a tow/haul mode? Maybe a button on the end of your shift lever? If so, it will downshift automatically going down a grade to keep you at the speed where you applied the brake. On my Silverado it?s pretty hard to spot that button unless you?re looking for it.sc4668 said:
O
Oscar Mike
Guest
Whenever I am towing I push the Tow/Haul Button and leave it there. No need to change back and forth, you have a computer doing the work of coordinating engine, transmission, etc. let it do its job.
When towing, use tow/haul and leave it there.
As for downshifting to help with braking, it all depends on how tow/haul in your particular vehicle is designed. Tow/haul might be something as simple as the transmission shifting a bit later in each gear, to managing speed going downhill, my 2001 Tahoe only did the former and my F250 diesel does a full compliment of shifting to maintain speed and performance uphill or down.
As for downshifting to help with braking, it all depends on how tow/haul in your particular vehicle is designed. Tow/haul might be something as simple as the transmission shifting a bit later in each gear, to managing speed going downhill, my 2001 Tahoe only did the former and my F250 diesel does a full compliment of shifting to maintain speed and performance uphill or down.
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