Downshifting to use engin brake coming downhill

[1engineer]

If you seriously think you're not adding stress to a transmission by engine braking, you're delusional. The speed is being dissipated by friction in the trans and that equals heat which equals wear. You should google that tho. Also, I doubt I would die... However, I'm sure it's entirely possible to overheat your brakes and pikes peak isn't the only place it can happen. My solution would not be to use my transmission instead.

No [MENTION=78273]Jeremy556[/MENTION] is not delusional. You actually think friction in the transmission is what slows you down?
Question: What is the difference in the "stress to a transmission" of backing up a really steep hill in reverse versus coming down that same hill in first gear and not using the brakes?

 

[Jeremy556]

If you seriously think you're not adding stress to a transmission by engine braking, you're delusional. The speed is being dissipated by friction in the trans and that equals heat which equals wear. You should google that tho. Also, I doubt I would die... However, I'm sure it's entirely possible to overheat your brakes and pikes peak isn't the only place it can happen. My solution would not be to use my transmission instead.

What is slowing you down is the pistons compressing air.
So what would your solution be? Normal vehicles cannot descend Pike's Peak, or other similar grades without quickly overheating their brakes to the point of failure.

 

[hearno]

These aren't jake brake equipped motors. Yes, the engine's compression cycle is part of it but so is friction in the drivetrain. Also, not being able to match revs puts more stress on the clutch packs. Holding yourself on a hill with the trans and not brakes is discouraged in the owner's manual. My solution would be to stop for a minute to let the brakes cool down.

 

[1engineer]

These aren't jake brake equipped motors. Yes, the engine's compression cycle is part of it but so is friction in the drivetrain. Also, not being able to match revs puts more stress on the clutch packs. Holding yourself on a hill with the trans and not brakes is discouraged in the owner's manual. My solution would be to stop for a minute to let the brakes cool down.

So that's why on the 5th gen Toyota has automatic built in engine braking?

 

[eddiebx]

These aren't jake brake equipped motors. Yes, the engine's compression cycle is part of it but so is friction in the drivetrain. Also, not being able to match revs puts more stress on the clutch packs. Holding yourself on a hill with the trans and not brakes is discouraged in the owner's manual. My solution would be to stop for a minute to let the brakes cool down.

How/when would you even need to rev-match if you're trying to go down a hill in one gear, lol. If it bothers you that much you can slow down to a stop first and then drop the gear and continue rolling down.

I don't mean this question offensively, but do you know how to drive a manual transmission extensively? If you do, descending down a hill in lower gear as OP is talking about is no different than you shifting into 1st or 2nd letting go of the clutch completely and just coasting down; no clutch slipping at all, hence no rev-matching needed or even possible for that matter. The only time you would need to rev-match is if you're going too fast and want to downshift w/o slipping the clutch, but that's just for that exact instant while you are accomplishing the downshift.

Out of curiosity what page of the manual are you talking about? All I see in the manual is this:

●Use engine braking (downshift) to maintain a safe speed when driving
down a steep hill.
Using the brakes continuously may cause the brakes to overheat and lose
effectiveness. (→P. 175)

Here's the nifty chart that the above paragraph is pointing us to. I doubt Toyota would publish these kind of recommendations if they thought it would damage our drive trains

 

[Jeremy556]

These aren't jake brake equipped motors. Yes, the engine's compression cycle is part of it but so is friction in the drivetrain. Also, not being able to match revs puts more stress on the clutch packs. Holding yourself on a hill with the trans and not brakes is discouraged in the owner's manual. My solution would be to stop for a minute to let the brakes cool down.

Go turn a crankshaft with a wrench, then remove the spark plugs and try it again.

It will take you all day to get down the mountain, lol. You must live in a flat area.

 

[Greg_Canada]

Go turn a crankshaft with a wrench, then remove the spark plugs and try it again.

It will take you all day to get down the mountain, lol. You must live in a flat area.

I will agree that Hearno is completely incorrect.

Once a trans is in gear, you're not wearing out the clutch packs. It's likely a smaller load than what full throttle puts on the transmission.

I'm sorry but you are being plain ignorant. You are using the engine to slow yourself down. And guess what, when you engine brake, it does not use any fuel. Yep, the injectors are shut off. Crazy eh?

 

[hearno]

Oddly enough, when my camry's transmission went out and toyota declined to cover it under warranty after opening it up, their reasoning was "abuse." Guess what I used to do with it... Downshift to save wear on my brakes.

 

[1engineer]

Oddly enough, when my camry's transmission went out and toyota declined to cover it under warranty after opening it up, their reasoning was "abuse." Guess what I used to do with it... Downshift to save wear on my brakes.

So you are basing this argument over one personal experience? Sorry for your loss but the other guys are right - you are wrong.

 

[LandCruiser]

Before I started driving AT trucks I barely used the brakes. Most driving situations could be dealt with by engine braking... and downshifts really help control deceleration.

I know new transmission algorithms incorporate downshifting and all, but they can't see what's ahead like I can.

I think that an entire generation raised on automatics doesn't even get that engine braking is normal, acceptable, and a good thing.

...except exhaust brakes, those are just damn obnoxious and sound like Satan taking a shit.

 

[JB.]

Hearno,

The owners manual has a ton to say about engine braking. Nothing is cautionary from a wear standpoint and it explicitly recommends engine braking when descending steep hills.

 

[badhabits]

:lookout:After 40 years driving everything from 2 to 24 wheels, both manual and auto all I have ever been taught is to use lower gears on a down hill slope. This practice may be slightly harder on some parts of the drive train if not applied correctly,(shifting to fast or into to low a gear). Loosing your brakes is far worse than the slight wear on the drive train. Engine compression has been a valid braking method for descending hills for almost as long as there has been transmissions. Do not try to tell me that running in lower gears destroys transmissions, ask any truck driver. Driving the 4runner is no different.

Yes I meen 24 wheels I drove heavy equipment haulers. My maiden voyage in a road tractor was over rt 60 in WV.
:driving:

 

[badhabits]

Before I started driving AT trucks I barely used the brakes. Most driving situations could be dealt with by engine braking... and downshifts really help control deceleration.

I know new transmission algorithms incorporate downshifting and all, but they can't see what's ahead like I can.

I think that an entire generation raised on automatics doesn't even get that engine braking is normal, acceptable, and a good thing.

...except exhaust brakes, those are just damn obnoxious and sound like Satan taking a shit.

First time I heard that description of a jake brake.

:toilet:

 

[jambo]

Mine does it automatic. 2012 sr5

 

[diverscale]

Before I started driving AT trucks I barely used the brakes. Most driving situations could be dealt with by engine braking... and downshifts really help control deceleration.

I know new transmission algorithms incorporate downshifting and all, but they can't see what's ahead like I can.

I think that an entire generation raised on automatics doesn't even get that engine braking is normal, acceptable, and a good thing.

...except exhaust brakes, those are just damn obnoxious and sound like Satan taking a shit.

:shocked:

 

[1000MPH]

This thread is depressing:yield:

...except for the jake brake stuff

 

[icsa]

Oddly enough, when my camry's transmission went out and toyota declined to cover it under warranty after opening it up, their reasoning was "abuse." Guess what I used to do with it... Downshift to save wear on my brakes.

Well, it depends on when you downshift. You don't downshift to slow down; you first use the brakes to slow down to the appropriate speed, then downshift to the gear that matches that speed. Engine braking is used to maintain speed.

 

[ThePro]

Well, it depends on when you downshift. You don't downshift to slow down; you first use the brakes to slow down to the appropriate speed, then downshift to to the gear that matches that speed. Engine braking is used to maintain speed.

No, engine braking is just that: braking. It uses the resistance of the engine to decelerate instead of, or in addition to, wheel brakes. The ECU is smart though, it won't let you downshift to a gear where the RPMs would be too high. You hear the little "beep beep" warning if you try that. If you are within the rev limits of the next lower gear, downshifting will slow you down. That is both normal/acceptable use and by design. I am not sure how that stuff is in any way unclear...

 

[LightRanger]

Well, it depends on when you downshift. You don't downshift to slow down; you first use the brakes to slow down to the appropriate speed, then downshift to to the gear that matches that speed. Engine braking is used to maintain speed.

In HS we moved from Orange County to snow country. My mom, who grew up in Orange County, didn't really know how to drive in the snow, but people had told her to use her brakes less and engine brake.

On the way back from XC ski practice in our 2WD Suburban (bought in Orange County long before we knew we were moving), we were descending a long grade on I-80 in a pretty gnarly storm. My mom decides to downshift without lightly braking to a better shifting speed first...

Nothing like sliding sideways at 35MPH in a Suburban with eight highschoolers and a screaming mother. :bounce: She made me chain it up after that... for the remaining five miles to the snowline. Unfortunately I wasn't allowed to drive other kids, or we would have been fine.

 

[icsa]

No, engine braking is just that: braking. It uses the resistance of the engine to decelerate instead of, or in addition to, wheel brakes. The ECU is smart though, it won't let you downshift to a gear where the RPMs would be too high. You hear the little "beep beep" warning if you try that. If you are within the rev limits of the next lower gear, downshifting will slow you down. That is both normal/acceptable use and by design. I am not sure how that stuff is in any way unclear...

There is a difference between "what you can do" and "what you should do". See the Suburban example above.