Engine Braking

[b1nda]

Does engine braking with a manual transmission hurt the transmission? Does it just depend on the transmission, etc?

[cfc1]

Well.. the way that i was taught to drive (years ago btw) was to go down my gears to help slow the car down.. I.E. use the engine break as well as the normall breaks. This should not hurt either the engine or the transmission.

[earpl]

i use the engine braking a lot, well most of the time.

[Demonic Angel]

Rich has always used engine braking and has always said it causes no harm at all.... so I tend to engine brake more these days than I used to!

I find you slow down quicker when combining braking and engine braking, than just braking alone....

[Kerby]

yeah i was taught to drive without usin engine brakin. but i have kinda got into the habbit myself. plus when ur approachin lights and they suddenly change ur always in the right gear to carry on

[Jones~32]

I always use engine braking, just got into the habit of it

takes some of the stress off the brakes :)

Mike

[cfc1]

And you find that you will get more life from your break pads

[GIDDLEPIN]

Try doing it on your test instead of block changing and they'll fail you

[T600]

I belive that engine / gearbox braking is correct in certain circumstances. The IAM teach:-

Gears to go, brakes to slow.

And that new brakes are very cheap compared to a new gearbox.

However, that doesn't mean you shouldn't use engine braking (apologies for double negative). Down a long hill using the engine to hold the car's speed is advocated. Using the brakes in these circumstances could lead to brake fade.

Also, when slowing for an obstruction ahead, using the engine to slow the car in the gear you are in is fine. But in this situation I wouldn't normally keep changing down the gears to get more braking as the car's speed reduced. I'd just use the brakes and be ready to change into the correct gear at the appropriate time.

It depends very much on the situation, the conditions, the vehicle you're driving etc.

[Red Yaris 54]

I was always told that it was cheaper to replace brake pads/shoes than clutches/gearbox :bookworm:

But now I drive the MMT as I brake the gears change down anyway

[Blue84]

I use a combination of both really, I was taught to drive by changing down the gears individually but also block changes too, I still do the odd block change now - depends on the circumstances really.

Extreme engine braking can't be good for the engine tho I imagine

[nrgizerbunny]

engine braking doesn't really harm the transmission. gearboxes are constant mesh (not like a push bike) and the power goes through the baulk rings.

Engine braking is good but it does mean you'll burn more fuel.

If you are changing down its usually if you mismatch the rpm you eat the clutch. which is why you should heel toe

[Black Knight]

nrgizerbunny, that would once have been true with carburetor engines where the air flow draws the fuel in. These days it isn't though. With modern fuel injection systems the ECU looks at the demand being made of the engine and the RPM and adjust fuel injestion appropriately. If the engine is being driven by the transmission (as in engine braking) it can cut fuel supply completely and will conserve fuel.

Engine breaking does absolutely no damage to the engine or transmission. The only time it could do is if you're trying to force past the syncro-mesh to get the gear you're after

[Gnome]

So in conclusion, no, it doesn't hurt your transmission...

:D

[GIDDLEPIN]

So in conclusion, no, it doesn't hurt your transmission...

:D

←

Only if you don't change from 5th to 1st at 100 mph!

[T600]

Or 5th to Reverse.

I'm pleased we're going to be back to two x 5 speed cars.

My last 3 cars all had sixth gear where reverse is on g/fs Corolla (and on my MR2).

Never quite got it into reverse at 70 on the motorway, but almost tried a few times. I imagine that would do some damage if it would go in.

[GIDDLEPIN]

Or 5th to Reverse.

I'm pleased we're going to be back to two x 5 speed cars.

My last 3 cars all had sixth gear where reverse is on g/fs Corolla (and on my MR2).

Never quite got it into reverse at 70 on the motorway, but almost tried a few times.  I imagine that would do some damage if it would go in.

←

It was the same in the gen7 that I had, not much of a gate between 1st and reverse, I always had to ease the clutch before setting off to make sure it went in the direction intended

[nrgizerbunny]

nrgizerbunny, that would once have been true with carburetor engines where the air flow draws the fuel in. These days it isn't though. With modern fuel injection systems the ECU looks at the demand being made of the engine and the RPM and adjust fuel injestion appropriately. If the engine is being driven by the transmission (as in engine braking) it can cut fuel supply completely and will conserve fuel.

Engine breaking does absolutely no damage to the engine or transmission. The only time it could do is if you're trying to force past the syncro-mesh to get the gear you're after

←

Yes I agree with you to an extent. But I have quite a lot of experience with Bosch And Siemens VDO fuel injection systems (I don't think either of which are used on toyotas!) from my formula student days and when the engine is braking it sprays in more fuel than when its idle.

Apparently its something to do with the density of the air fuel mixture. If you compress air by itself with no fuel to 10.7 bar (petrol) then you risk the chance of a supersonic shockwave over the top of the piston (if its moving at high Mean Piston Speed ie engine braking). As you may or many not know mach 1 is a function of temperature which happens to be a function of air pressure/density.

Hence the fuel spray can not be killed completely (for prologned periods of time) unless there is 0 RPM on the engine and that can't happen otherwise you'd lose power steering, alternator etc etc.

That was my take on things but I shall look up in my motronic manual as i'm sure i've made a balls up somewhere!

But I do agree with you about it not being as bad as cars with carbs! :D

have a nice day

sanj

[mikeb]

nrgizerbunny, that would once have been true with carburetor engines where the air flow draws the fuel in. These days it isn't though. With modern fuel injection systems the ECU looks at the demand being made of the engine and the RPM and adjust fuel injestion appropriately. If the engine is being driven by the transmission (as in engine braking) it can cut fuel supply completely and will conserve fuel.

Engine breaking does absolutely no damage to the engine or transmission. The only time it could do is if you're trying to force past the syncro-mesh to get the gear you're after

←

Yes I agree with you to an extent. But I have quite a lot of experience with Bosch And Siemens VDO fuel injection systems (I don't think either of which are used on toyotas!) from my formula student days and when the engine is braking it sprays in more fuel than when its idle.

Apparently its something to do with the density of the air fuel mixture. If you compress air by itself with no fuel to 10.7 bar (petrol) then you risk the chance of a supersonic shockwave over the top of the piston (if its moving at high Mean Piston Speed ie engine braking). As you may or many not know mach 1 is a function of temperature which happens to be a function of air pressure/density.

Hence the fuel spray can not be killed completely (for prologned periods of time) unless there is 0 RPM on the engine and that can't happen otherwise you'd lose power steering, alternator etc etc.

That was my take on things but I shall look up in my motronic manual as i'm sure i've made a balls up somewhere!

But I do agree with you about it not being as bad as cars with carbs! :D

have a nice day

sanj

←

That's an interesting theory. You are right though, most modern ECUs don't automatically cut fuel completely on overrun. Toyota's TCCS has an input from the brake light circuit, and it only cuts fuel completely on overrun when the brakes are being applied simultaneously. I think the reason for this is to prevent lurching that could be caused by total fuel cut. Many ECUs also have tip-in and tip-out algorithms to prevent instability or loosing traction, which means fuel is not cut instantly on overrun.

If you anticipate what's going on up ahead, and lift off the throttle in plenty of time, then there's no need to change down the gears to get braking in each one. The current gear should provide a usable amount of engine braking by itself. Also, applying the brakes as early as possible means you don't have to use them so hard, and they will last much longer.

[Black Knight]

If you were doing formula student I'm guessing you used some sort of high revving bike engine?

Not sure about these circumstances but in a road going car they don't normally suffer from this problem. You can run them for extended periods with no fuel injection without causing damage.

Some Toyota engines do use Bosch injection and management systems.

[Tegan]

I always use engine braking, just got into the habit of it

takes some of the stress off the brakes :) 

Mike

←

It may take stress off the brakes but pads and discs are cheaper to repair/replace than gearboxes! ;)

[Karma Supra]

My ECU definitely does not cut fuel on over-run.. the pops and bangs confirm that!!!

I was taught NOT to use engine braking if I wanted to pass my test, as they see it as a vehicle slowing down without the brake lights on!!

Then again also teach you to steer in such a manner that if the back end ever stepped out it would be imposible to catch!

I always gear down to slow down (even in my auto ;)) but usually tap the brake pedal first to let the half wit behind me know what I am doing.... it also helps keep my wheels cleaner

[COROLLA-KID]

i aways engine brake. had to change the pads once so im never doing it again ( who says im tight)

[Bibbs]

Last time I did *serious* engine braking .. 5th and reverse popped out the back of the G'box ..

[stevetubbyturbo]

when driving on the roads i have hardly any engine braking (the Surf being an auto) so i have to use the brakes more than most drivers would with a manual.

But when off roading and have the transmission in low its completely the opposite i hardly ever use the brakes as the transmission has loads of engine braking to the point that i can go down a very steep hill and not have to use the brakes as the engine is doing all the braking i need.