[Gabbykat]

I tried using the low gears when going down steep long hills so I don't have to brake as much but the BMW delivery specialist told me that doing so will not help the engine in the long run especially since I intend to keep the car for 10 years plus.

I'd always thought that switching gears when going up or down hills would save the engine and the brakes. Is that just old school?

Do you just leave it in 'D' and let the automatic transmission do everything?

[jordantii]

I am always in S or M unless I am cruising on an empty highway.

[Gabbykat]

Originally Posted by jordantii

I am always in S or M unless I am cruising on an empty highway.

Is yours an automatic?

Could you explain s gears? Is that just manual gears but sportier, more responsive amd in the sport mode?

[3.0L]

Originally Posted by Gabbby

I tried using the low gears when going down steep long hills so I don't have to brake as much but the BMW delivery specialist told me that doing so will not help the engine in the long run especially since I intend to keep the car for 10 years plus.

I'd always thought that switching gears when going up or down hills would save the engine and the brakes. Is that just old school?

Do you just leave it in 'D' and let the automatic transmission do everything?

I shift down a gear or two in both of my cars when going down a steep grade. So what if the engine is spinning 3000 RPM. Or even 3300 RPM. Your delivery specialist is full of it. These cars were meant to be driven, and that doesn't mean like the proverbial little old lady to church on Sunday.

[aozer]

Originally Posted by Gabbby

Is yours an automatic?

Could you explain s gears? Is that just manual gears but sportier, more responsive amd in the sport mode?

S is automatic but will stay at a higher rpm when cruising and give you more responsive shifts

if you put it in S and then shift yourself, the car will remain in manual mode indefinitely whereas if you have it in D and shift yourself eventually the car will return to auto mode

[TheCaptain]

Using the engine to do the job of the brakes will cause increased wear on the components of the drivetrain and reduce the wear on the brake pads.

Brake pads are designed to wear out and be replaced as necessary, the drivetrain is not.

[Elvisfan]

Putting more wear on the engine and transmission to save the brakes doesn't make any sense to me.

[Gabbykat]

Originally Posted by Elvisfan

Putting more wear on the engine and transmission to save the brakes doesn't make any sense to me.

I am so confused now. I'd always thought changing gears on hills was giving the engine more support and power. Instead of flooring it to go up a hill, i sometimes switch to a lower gear...like as if I was driving a manual. Or when starting on a hill, is it better to shift into a lower gear?

After talking to the delivery specialist, it seems like I was completely wrong?!

So i can't think of it as a manual then where you can get more power and control in a lower gear, say during winter driving when going slow is better than having to brake more?

[nike001]

Originally Posted by TheCaptain

Using the engine to do the job of the brakes will cause increased wear on the components of the drivetrain and reduce the wear on the brake pads.

Brake pads are designed to wear out and be replaced as necessary, the drivetrain is not.

Originally Posted by Elvisfan

Putting more wear on the engine and transmission to save the brakes doesn't make any sense to me.

What the hell are you guys even talking about?

Using a lower gear to slow the vehicle is called engine braking and is in NO way increasing wear on the engine/drivetrain (granted you're not downshifting 6,000+ RPM). I'm not even sure how one can argue that it does...? The momentum of the vehicle is what is keeping the engine rotating, and not fuel combustion. The compression itself of the engine is what ultimately slows the vehicle.

Like c'mon guys...

[B58togo]

^^

+1

It's like people who think downshifting manuals when approaching a stop will hurt their clutch and/or syncros.

[Joaco135]

^^^

+2

[Gabbykat]

So the BMW delivery specialist is wrong? Shifting to a lower gear will not damage the engine in the long run?

Do you also drive in a lower gear in snow/ ice conditions then?

[pikcachu]

Originally Posted by Gabbby

So the BMW delivery specialist is wrong? Shifting to a lower gear will not damage the engine in the long run?

Do you also drive in a lower gear in snow/ ice conditions then?

If you use the car it will wear the engine in the long run....

If you buy the car and just leave it parked... the engine will last more too....

If you upshift at 2k rpm the engine will last more than if you upshift at 5krpm...

Downshifting at every stop to 6k rpm will definitely not help with wear.... but ridding the brakes a mile going down hill and warp the brakes it's most likely more than the damage the transmission will get by going into 3rd at 4000 rpm for that time

[pz619]

I drive almost exclusively in M and I aggressively downshift. I treat it like a sports car that's fun to drive, not as a museum piece. If something breaks out of warranty, I'll simply fix or replace it. Honestly I'm not worried about it. The car is pretty stout.

[TheCaptain]

I didn't mean to give the impression that engine braking should never be used, obviously it's a balance between that and regular braking, and using either to an extreme is harmful. The notion of 6k RPMs is just a made up number. Using engine braking from 6k is more harmful than from 5k, which is more harmful than from 4k, and so on.

Perhaps it's a bit technical, but it's the inertia of the vehicle that keeps it going, not the momentum, and retarding forces within the engine act to change the speed of the car. If you want to characterize it using momentum, the force from the engine acts over a period of time, so the engine applies an impulse to the car, and this impulse changes the car's momentum. The change in momentum is equal to the impulse.

[ianp622]

Ok, could people talking about engine wear elaborate? Because in an automatic, you're going to have some difference in speed in the torque converter (which is mostly a bunch of slush), and you're going to have a load in the engine, which is normal. The pistons will be moving at a different speed than what's coming in through the torque converter (so it's already damped), and it's really just the timing of the combustion that is slowing the car.

The advantage of safety in saving your brakes downhill is the primary concern. If you have a long downhill slope your brakes might fade from the heat, and that's much worse than having your engine help a bit with slowing. After all, if you coast to a stop, you're engine braking, but nobody worries about that.

[Maynard]

Originally Posted by TheCaptain

Using the engine to do the job of the brakes will cause increased wear on the components of the drivetrain and reduce the wear on the brake pads.

Brake pads are designed to wear out and be replaced as necessary, the drivetrain is not.

This is the key - wear out those brake pads and change them - MUCH cheaper. Analogies to letting the car sit and not drive it are silly - this is a case of 'which part do you want to wear out - brake pad or internals').

Originally Posted by nike001

What the hell are you guys even talking about?
......
Using a lower gear to slow the vehicle is called engine braking and is in NO way increasing wear on the engine/drivetrain (granted you're not downshifting 6,000+ RPM). I'm not even sure how one can argue that it does...?

Sorry to burst the bubble, but engine braking DOES put a particular and fairly unique type of stress on an engine. It isn't the worst thing you can do but it does put in stresses, and they are 'backwards' to usual stressors in most cases (i.e. instead of force coming through the piston/crank/drivetrain, they are feeding back the other direction). You do this on a low level every time you lift throttle, but upshifting down a hill will greatly accentuate the forces involved, and the wear from it. This is part of the extra wear and tear you see from stop and go driving (you know how it isn't just the brakes that you worry about in a commuter car, but also the engine and tranny?). Many of those parts are not built to take that type of stress, or are wearing much faster in that mode - many materials wear-in in one direction and then are sheared the opposite way. I believe that this is also very different for manuals vs. autos, but my AT tech info is pretty outdated for these cars. Engine braking got most of it's play from truckers, who are using it for very different reasons and with very different machinery; FWIW, I think it is LESS destructive now, with port FI, than it used to be, but still unnecessary wear.

Bottom line is that if you want to eliminate a rather pointless way to find out what BMW charges for engine parts and service, you use the brakes instead (that is why the nice engineers overbuilt them), especially if you are feeling the need to upshift to get more braking action.

And to the other poster who asked about going UP hills, downshifting to stay in the power band is best (which in these cars isn't hard, as it kicks in fully by about 2k rpm).

[ZPrime]

Originally Posted by Maynard

This is the key - wear out those brake pads and change them - MUCH cheaper. Analogies to letting the car sit and not drive it are silly - this is a case of 'which part do you want to wear out - brake pad or internals').




Sorry to burst the bubble, but engine braking DOES put a particular and fairly unique type of stress on an engine. It isn't the worst thing you can do but it does put in stresses, and they are 'backwards' to usual stressors in most cases (i.e. instead of force coming through the piston/crank/drivetrain, they are feeding back the other direction). You do this on a low level every time you lift throttle, but upshifting down a hill will greatly accentuate the forces involved, and the wear from it. This is part of the extra wear and tear you see from stop and go driving (you know how it isn't just the brakes that you worry about in a commuter car, but also the engine and tranny?). Many of those parts are not built to take that type of stress, or are wearing much faster in that mode - many materials wear-in in one direction and then are sheared the opposite way. I believe that this is also very different for manuals vs. autos, but my AT tech info is pretty outdated for these cars. Engine braking got most of it's play from truckers, who are using it for very different reasons and with very different machinery; FWIW, I think it is LESS destructive now, with port FI, than it used to be, but still unnecessary wear.

What are you on about??

There is no appreciable additional wear to a motor when using it to "engine brake" a car. You are effectively "engine braking" every time you lift throttle. The ECU cuts spark and fuel, and the engine simply continues to reciprocate and act as a giant air pump. The closed throttle plate (or intake valves in the case of a throttle-less BMW) cause the intake stroke to create a vacuum, and that is what helps slow the car.

Downshifting a car to a lower gear to help maintain the speedlimit on a decline is actually the smart thing to do, because it helps prevent the brakes from overheating. Do you want to drop it down to 2nd and let the RPMs sit up near redline; well no, that's not the greatest thing (more RPM = more heat and stress on all components)... but running it in vacuum at 3-5k on a downhill isn't going to kill it or cause any major wear to the motor that's any different from what you'd get from accelerating to freeway speed or mashing the throttle to pass a slow-poke.

With a planetary / torque converter auto, the only concern I'd have is if the transmission doesn't rev-match. I haven't driven the ZF auto that's in the F22/F23 so I don't know if it does or not? If it doesn't rev-match / throttle blip on a downshift, there's going to be additional wear on the transmission due to the speed mismatch.

[Maynard]

What I'm 'on about' is that it does not make sense to use additional engine braking (downshifting) when you already have a braking system that is designed to be race ready, and with at least 2 separate systems to help avoid fade ('overheating'). You aren't driving a 40-year old Peterbilt with janky air brakes that needs this technique.

Engine braking does put a different kind of load on an engine - the braking comes from the vacuum effect of closed throttles while the engine cycles, and force is being fed back through the driveline in reverse. That is not the typical situation in the tranny or the cylinders, especially in a turbo motor, where they are used to being pressurized (pretty much the opposite forces from the acceleration examples that you mentioned). It can, and does, cause certain kinds of wear that will be amplified if you are downshifting to create higher revs. The engineers spent tons of time designing the AT programs, so if it doesn't downshift for you, there is probably a good reason. I don't know if that counts as 'appreciable' extra wear in your book, but since the possible damage is likely to show up beyond the warranty period I'm sure that the potential costs would be VERY appreciable, so for me I'll skip the financial Russian roulette. Bottom line is, if you are going to take some action to slow down, best to use the brake instead of downshifting.

[inc235]

I don't think race-ready include long downhill braking scenarios (like 5-8% grade >1mile).
In general, I agree there will probably be no overheating but having engine rev ~3k rpm probably doesn't hurt engine either since we use it anyways.
Whenever you let off gas pedal in sports mode, it holds rev/engine brakes, so, would you shift up to keep rpm <2k then?

Originally Posted by Maynard

What I'm 'on about' is that it does not make sense to use additional engine braking (downshifting) when you already have a braking system that is designed to be race ready, and with at least 2 separate systems to help avoid fade ('overheating'). You aren't driving a 40-year old Peterbilt with janky air brakes that needs this technique.

Engine braking does put a different kind of load on an engine - the braking comes from the vacuum effect of closed throttles while the engine cycles, and force is being fed back through the driveline in reverse. That is not the typical situation in the tranny or the cylinders, especially in a turbo motor, where they are used to being pressurized (pretty much the opposite forces from the acceleration examples that you mentioned). It can, and does, cause certain kinds of wear that will be amplified if you are downshifting to create higher revs. The engineers spent tons of time designing the AT programs, so if it doesn't downshift for you, there is probably a good reason. I don't know if that counts as 'appreciable' extra wear in your book, but since the possible damage is likely to show up beyond the warranty period I'm sure that the potential costs would be VERY appreciable, so for me I'll skip the financial Russian roulette. Bottom line is, if you are going to take some action to slow down, best to use the brake instead of downshifting.

[RotorOver]

Here's an experiment those with an AT can try. While driving in Sport mode apply the brake. What happens? The automatic transmission downshifts and RPM increases. Looks like engine braking to me. How is that any different than manually downshifting when slowing (assuming you're not taking RPMs to 5-6k)?

[pikcachu]

Originally Posted by RotorOver

Here's an experiment those with an AT can try. While driving in Sport mode apply the brake. What happens? The automatic transmission downshifts and RPM increases. Looks like engine braking to me. How is that any different than manually downshifting when slowing (assuming you're not taking RPMs to 5-6k)?

There is nothing wrong with downshifting while you brake
The difference is that the brakes are the one doing the work.... you just downshift to stay on an optimal RPM range torque/hp wise...

It's not you downshift to break...it's that you downshift because you braked

Problem with using downshifting for braking is that is very uncontrollable also.... you will get a lot of braking around 6krmp and you might even get some lockup but as rpms go down you lose braking.... you would be transferring weight like in squirts....instead of a smooth transfer you get with the brakes....

You won't see drivers using downshifting for braking in racing either.... and they sure don't care if the transmission would last just 1 race...it's just braking with the transmission is hard to control... like unconsistent lurching....which doesn't translate to fast