[greenfrog]

Hi all,


I recently purchased a relatively new BMW 3 Series with the M Sport pack which includes the paddle shifters and whatnot.

Having switched from a manual car, I'm wondering if engine braking is particularly bad for the transmission in a car that can be in automatic mode OR manual mode, as I don't know the ins and outs of whats going on under the bonnet. I always used to downshift to about 3000rpm continuously to slow down when seeing a red light ahead for example (as well as using the brakes lightly of course). Is this a good idea in my new car?


Many thanks!

[sspade]

Even though I do not downshift my auto box to slow down... Im interested to hear the answer to this question...

[bimmer456]

I engine brake all the time that's what paddle shifters are for. 50k plus miles later no problem.

[outofphase]

I don't know a ton about the ZF transmission but my guess is you should be fine. The wear from the downshift should be relatively similar as that of an upshift. If anything I'd guess there'd be LESS load on the clutches during deceleration than when accelerating.

Hopefully someone with more knowledge can chime in.

[Wolfus Aurelius]

I've used engine braking only rarely, mainly when descending a steep slope in Colorado, New Mexico, or Texas (yes, Texas has some steep pitches). I thought that was the main use for it.

[floydarogers]

Given that recent ZF transmissions rev-match downshifts, I wouldn't expect any problems. My older e90 335d with the ZF6HP26 at 135K shows no problems attributable to clutch wear. Lots of people run in sport mode, which is fairly aggressive in it's use of downshifts, and no one seems to have complained of wear problems.

[kern417]

It's not going to cause the trans to fail prematurely if that's what you're worried about. Keep in mind that the car engine brakes no matter what when you're slowing down in gear. It's the most efficient way to slow down.

All the manual mode does is force the actuators to move when you tell it too. It's not really different from other automatics.

[Gen13 F36]

Go drive on sport or sport + mode on auto then just decelerate and you will know the car use engine braking when the transmission downshifts by itself. So I don't think there is harm on this. Unless your okay driving on comfort or eco pro😂

[Zanity]

Engine breaking is absolutely fine, like mentioned above, both in sport+ and ecopro, the car downshifts because sport+ keeps your rev up for power readiness and ecopro downshifts to save fuel. You'll notice this much more when you're going down hill and touch the brake, the car will downshift everytime. ZF8 is built for it, there's no damage done whatsoever. The shift is smooth too, if you feel a jolt then your transmission may have issues.

[NoCrease DeQuis]

I drive exclusively in Sport DS (shifter to the left), and the engine 'brakes' all the time through slightly aggressive downshifts. I have had the car for about a year (f30 328) and have had no tranny problems.

[BMWILUVU]

Originally Posted by greenfrog

Hi all,


I recently purchased a relatively new BMW 3 Series with the M Sport pack which includes the paddle shifters and whatnot.

Having switched from a manual car, I'm wondering if engine braking is particularly bad for the transmission in a car that can be in automatic mode OR manual mode, as I don't know the ins and outs of whats going on under the bonnet. I always used to downshift to about 3000rpm continuously to slow down when seeing a red light ahead for example (as well as using the brakes lightly of course). Is this a good idea in my new car?

Many thanks!

Whatever you choose to slow you down, wears down. You will be putting more wear on the ZF with engine braking. Brake pads are cheaper than a ZF unit.

[NYG]

Engine braking is what men do.

Realistically though, you're wearing out parts every degree your tire rotates, every stroke, every shift. Some argue that gearing and components of your drivetrain take a little more wear (insignificant and no scientific data to back it up) and that it makes more sense to wear out your replaceable pads than your drive train but there's a lot more to it than just wearing out pads. Kinetic energy converts to thermal energy which will affect more than just your pad but again, in daily driving this will be insignificant just like engine braking.

That being said, I've been engine braking my whole life and never had an issue as a result of it. It also forces you to be more attentive while you drive which is never a bad thing.

[upsidedownfunnel]

The transmission solenoids/clutch packs and torque converter lockup clutch are definitely being worked out when you downshift. I'm not saying you'll ever notice slippage or wear any faster than if you didn't, but I'm just wondering what the point would be. What's the goal? To save your brakes? To sound cool while you're slowing down? If it's the former, don't bother. If it's the latter, then do it. If that theoretically did advance transmission wear, you gotta figure it only costs fractions of a penny every time you do it at most. Probably cheaper than getting an exhaust. If it's for slowing down while going downhill, then definitely downshift without hesitation.

Even in a manual, it's my opinion that downshifting at a stoplight is unnecessary. You might save a couple thousand miles worth of brake life yet use up a couple thousand miles of synchro and clutch wear. Brakes are significantly cheaper and easier to replace as well. In an automatic, where transmission rebuilds and service are much more expensive than in a manual, I just don't see the point. I stopped doing this (for the most part) in my early 20s. Just realized there was very little point. I will do it if I know I won't be coming to a complete stop like on a turn or at an imminent green light, though.

[HighlandPete]

Originally Posted by upsidedownfunnel

The transmission solenoids/clutch packs and torque converter lockup clutch are definitely being worked out when you downshift. I'm not saying you'll ever notice slippage or wear any faster than if you didn't, but I'm just wondering what the point would be. What's the goal? To save your brakes? To sound cool while you're slowing down? If it's the former, don't bother. If it's the latter, then do it. If that theoretically did advance transmission wear, you gotta figure it only costs fractions of a penny every time you do it at most. Probably cheaper than getting an exhaust. If it's for slowing down while going downhill, then definitely downshift without hesitation.

Even in a manual, it's my opinion that downshifting at a stoplight is unnecessary. You might save a couple thousand miles worth of brake life yet use up a couple thousand miles of synchro and clutch wear. Brakes are significantly cheaper and easier to replace as well. In an automatic, where transmission rebuilds and service are much more expensive than in a manual, I just don't see the point. I stopped doing this (for the most part) in my early 20s. Just realized there was very little point. I will do it if I know I won't be coming to a complete stop like on a turn or at an imminent green light, though.

Very much my thinking as well.

Also add, if drivers use engine braking to save brakes, users are likely driving pretty hard to wear brakes fast. In that case there will be extra wear on the drivetrain, using heavy engine braking, as a substitute to brakes.

Users comment they don't feel there is extra wear, on what is that assessment made? 100,000+ miles use and analysis of the transmission fluid?

As I see it, work the gearbox harder, (including heavy use of engine braking), the least you can do is consider a fluid change at lower mileage than lighter gearbox use.

[SW6Steve]

330d
Let the auto box do it's own thing when slowing down. Never ever thought about down shifting using the paddles for slowing in traffic, traffic lights etc! Use the brake🙄
Paddles are for fun in the twisties!

[Gen13 F36]

Originally Posted by BMWILUVU

Whatever you choose to slow you down, wears down. You will be putting more wear on the ZF with engine braking. Brake pads are cheaper than a ZF unit.

Yeah of course but this is normal wear unless you down shift and end up with RPM at 6000 for engine brake....lmao

[Brett530]

This does not address driving around town using engine braking, but the concepts still apply (from the F30 Manual):

Hills
Drive long or steep downhill gradients in the gear
in which the least braking is required. Otherwise,
the brake system may overheat, resulting in a
reduction in the brake system efficiency.
Automatic transmission:
You can increase the engine's braking effect by
shifting down in the manual mode of the auto‐
matic transmission.

Avoid load on the brakes
Avoid placing excessive load on the brake
system. Light but consistent brake pressure can
lead to high temperatures, brake wear and pos‐
sibly even brake failure.

Do not drive in neutral
Do not drive in neutral or with the engine
stopped, as doing so disables engine braking. In
addition, steering and brake assist is unavailable
with the engine stopped.

Edit: the F30 LCI manual includes:
You can increase the engine's braking effect by shifting down, going all the way to first gear, if needed.

[NormanConquest]

Originally Posted by bimmer456

I engine brake all the time that's what paddle shifters are for. 50k plus miles later no problem.

Ditto I'm near 60k and do it quite often to get the gun shot sounds from my exhaust.

[Logicoeur]

Engine braking is just downshifting and then coasting. You will be fine.

[donkey]

Originally Posted by upsidedownfunnel

Even in a manual, it's my opinion that downshifting at a stoplight is unnecessary. You might save a couple thousand miles worth of brake life yet use up a couple thousand miles of synchro and clutch wear. Brakes are significantly cheaper and easier to replace as well. In an automatic, where transmission rebuilds and service are much more expensive than in a manual, I just don't see the point. I stopped doing this (for the most part) in my early 20s. Just realized there was very little point. I will do it if I know I won't be coming to a complete stop like on a turn or at an imminent green light, though.

I think it's a good/safer habit to always be in the correct gear. If it wears the tranny a bit more so be it.

Plus engine breaking takes a lot longer than regular breaking, so you might save yourself a few red lights, and save wear on that side of things.

[HighlandPete]

Originally Posted by donkey

I think it's a good/safer habit to always be in the correct gear. If it wears the tranny a bit more so be it.

The 'right or correct gear' is an interesting point for an AT. Should be in the right gear without intervention, according to mode selected and driver adaptation working on the fly.

Manual intervention.... is it really necessary? Likely more a driver's choice than necessary, as there is a lot of gear flexibility in current AT programming.

Even engine braking works automatically, particularly on hills, when we prod the brake and instigate a down change or two..

[upsidedownfunnel]

Originally Posted by donkey

I think it's a good/safer habit to always be in the correct gear. If it wears the tranny a bit more so be it.

Plus engine breaking takes a lot longer than regular breaking, so you might save yourself a few red lights, and save wear on that side of things.

While coming to a stop at a stoplight, there is no "correct" gear. You're coming to a stop. You can stay in 5th gear until about 50 ft from the stop. It takes less than a second to shift into whatever gear you need if the light suddenly turns green.

What advantage do you think there is to sequential downshifting at every stoplight? Why wear out your synchros like that?