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Holding gas instead of brake on hill when stopped -- wear on transmission?

12K views 33 replies 16 participants last post by  keeton 
#1 ·
While stopped at a crosswalk on a fairly steep hill this morning, I noticed that the driver in front of me did not appear to be holding the brake while stopped, and I'm guessing that this driver was using the gas pedal to sort of "equilibrate" the backward rolling motion the vehicle would have without the foot brake being held by depressing the accelerator pedal just enough to keep the vehicle from rolling backwards. I know that in a manual transmission vehicle that doing this is very bad for the clutch, but I'm not knowledgeable enough about these newer automatic transmissions to know if this will do damage or wear to any part of the transmission, or if in general this is a bad idea. I tried it at the next crosswalk I stopped at, and it worked quite well to keep my RAV4 from rolling backwards (and I found it easier than using hill-start-assist or the parking brake trick). However, as I plan to keep the RAV4 for a long time, I don't want to do anything potentially damaging to it. Thanks in advance for any info on if this has no effect on the vehicle's longevity, or if it is a (potentially) damaging thing to do!
 
#2 ·
No, it's ok to hold the gas.
 
#3 ·
while you have an automatic transmission it still has clutches in it.....when the engine is at a lower rpm the clutches do not engage....however as the rpms go up the transmission builds pressure and slowly engages them to the point of full contact.....by holding the car on a hill using only the gas you are basically riding the clutch as if you had a standard......you may not do much damage doing it here or there.....do it long enough and you will kill your tranny......use the hand brake or hill hold function.....
 
#5 ·
by holding the car on a hill using only the gas you are basically riding the clutch as if you had a standard......you may not do much damage doing it here or there.....do it long enough and you will kill your tranny
Absolutely not true. AT use torque converters that function like hydraulic clutches with slippage. Doing that wastes gas and heats the tranny, but it doesn't directly wear clutches.

Edit, I didn't mean to say there are no clutches in AT. I meant to say the poster is incorrect stating that holding the car with gas is like clutch riding in manual tranny. It's not. Amen.
 
#8 ·
Sounds like a bad idea to me. First you'll create a hell of a lot of heat in the fluid from the torque convertor, second, it's just not safe. Should you accidently press the gas a bit harder you risk running over someone in the crosswalk and if you let up too much you risk rolling back into the car behind you if there's one there. Use the brake!
 
#11 ·
...First you'll create a hell of a lot of heat in the fluid from the torque convertor, second, it's just not safe....
This. The slippage is in the torque converter and heat is generated in the transmission fluid. Even then, our Ravs (along with virtually every modern car) has a water cooled transmission, which would mitigate all but the most egregious hill-holding (i.e. with a heavy trailer).

These issues have been known since my Dad's old Dynaflow. You do not put additional wear on the clutch pack(s) by keeping an automatic in the same gear.

Now, doing a drag racing start by dumping it from neutral to drive at 5000 RPM...>:D
 
#9 ·
my point was that using the gas and bringing the engine up to 1000,1200,1400 or more rpms to hold the car will in time damage the transmission.....and while i dont know auto transmissions that well i do know adding power from the engine to compensate for things such as hills or heavy loads will burn out clutch packs......like i said holding a car with an auto like that will damage a transmission.......
 
#12 ·
OK, as it sounds like it would quite probably be damaging to the transmission, I'll avoid it altogether and improve my skill with using hill-start-assist and the parking brake (which does need improvement, as although I often drive on hills I've rarely needed to stop on a steep incline with anyone behind me, so therefore I'm inexperienced). Thanks for all the responses!!
 
#29 ·
Actually, it is the other way around. The transmission fluid has lines that run to the radiator. There is a separate heat exchanger in the radiator for the fluid. As I said before, virtually all new cars today do it this way. You have to go waaay back to find some old Chevy Powerglides and Ford Fordomatics that did not use an auxiliary cooler.

I can't post a direct copy/paste image here, but the oil cooler lines are very well illustrated in the transmission chapters of the RAV4 service manuals.
 
#17 ·
I never said to keep the car on a hill by pressing gas. It's just unsafe and waste of gasoline.
Use the brake pedal for crying out load, the one to the left from the gas pedal.

The hill assist works for a couple of seconds and hand brake is great for uphill starts with manual tranny, but I don't see a point of using it in auto unless the hill is mighty steep, but then you can use the hill assist function for the short transition between brake pedal and gas pedal.
 
#18 ·
I've no qualms about using the accelerator to hold while stopped uphill except on some of San Fransco's hill-top intersections. It doesn't take much throttle at all. But you still have Hill-start Assist Control (HAC) which is far easier and safer to use than the emergency brake.
 
#21 ·
I guess perhaps my use of "hill" was unclear—the roads I'm taking about are some of the steeper streets in the Berkeley hills area, where even an automatic will roll backwards when moving from footbrake to gas pedal. It looks like hill-start-assist will be my best option.
 
#22 ·
Agreed. There are some hills around my area that the simple brake pedal to gas pedal doesn't work so well. Especially if there is a vehicle right on your butt at a light.

For this I use ebrake or left foot on the brake and right foot to start going.

Do what works for you Kauri as I think some of the replies from here are from folks in areas without steep hills.
 
#23 ·
Isn't applying gas to hold car still on a hill the same as applying the brake to hold car still at a stop light on level ground.? In both instances the car is in drive but stationary. The only difference I see is the "idle' speed is a little higher in the hill scenario.. Am I missing something? Is a high idle speed detrimental for an auto trans in drive when car is stationary?
 
#27 ·
I would think not.......at an idle of 7-800 rpms or whatever it is for the rav4 the transmission is designed to have some engine torque applied to it.....once you start raising the engine rpms you start building pressure in the transmission.......now you have higher engine rpm and transmission fluid pressure but the car is not moving......go outside and get into your car......put it in drive.....put one foot on the brake and one on the gas......using the gas raise the engine to 1000....1200 or so rpms and see how long til you start smelling something funny.....by using the gas to hold the car on a hill will have the same results.....
 
#24 ·
I don't have to deal with steep hills, or any hills for that matter, but if I did this makes the most sense to me:

cutthroat22 said----
"For this I use ebrake or left foot on the brake and right foot to start going."

It's pretty basic stuff folks :shrug:
 
#31 ·
Why would Toyota implement Hill-start Assist Control (HAC) if they didn't intend it to be used? It's for exactly the situations the OP described. So either use it or hold the foot brake with your left and let the engine idle.

As mentioned there are several reasons not to hold a car on a hill with the throttle but damage to the transmission isn't one of them. Yes, it will waste gas and generate a little heat in the torque converter but the TC is designed to slip and the radiator will dissipate the heat. No bands or clutches which could wear are slipping. They are all fully engaged or released.

We don't encounter such hill starts in my area but if I did I'd hold the car with the throttle if it was for a few seconds. Any longer I'd use the brake. (My HAC is not working due to the pedal arm sensor going bad and getting replaced with a resistor.)
 
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