Strange feeling on 6MT gearbox

[spd974]

Hi guys,

My new F80 M3 with 6 speed manual transmission now has 650 miles on the odometer.

Tonight, I took it for a spin and set the throttle to Sport +.

I noticed something I never experienced with any of my previous cars: when going from a lower gear (let say 5th) to an higher gear (6th), if I let go of the clutch too fast, It feels like something is "slipping" in the transmission.

This only happens in Sport + mode. It is quite hard to describe but it just feels so weird.

Do any of you guys with 6MT gearbox know what I am talking about and if this is normal?

Thanks in advance!

[lore2486]

it could be the torque management system, it delays the shifts

[spd974]

I don't know but I am definitely curious to see if other owners with same gearbox experience the same thing.

[Brasko]

I drive a 6-Speed. What do you mean by "sleep"? My guess is there might be a little bit of turbo lag in the lower RPM's if you throw it into 6th gear to early.

[spd974]

Originally Posted by Brasko

I drive a 6-Speed. What do you mean by "sleep"? My guess is there might be a little bit of turbo lag in the lower RPM's if you throw it into 6th gear to early.

Sorry I meant to write slipping. Haha

[BMW M4 PWR]

Originally Posted by lore2486

it could be the torque management system, it delays the shifts

This is it in a nutshell^^^ Although it doesn't "delay" the shift. It's ECU programming that intentionally cuts power and feeds it back progressively during an attempted fast (or racing) shift. It is a feature of many modern manual transmission performance cars nowadays and was done to maintain reliably in the powertrain and reduce warranty repairs for the manufacturers. In almost all cases it kills the vehicles' true straight-line potential and is excessive. It can be tuned-out of the DME with a competent flash tune* I don't know as of yet who's been successful at doing that but several claim they can. It's something I will be tuning-out in my 6-spd M4 in the future for sure.

[spd974]

Originally Posted by BMW M4 PWR

This is it in a nutshell^^^ Although it doesn't "delay" the shift. It's ECU programming that intentionally cuts power and feeds it back progressively during an attempted fast (or racing) shift. It is a feature of many modern manual transmission performance cars nowadays and was done to maintain reliably in the powertrain and reduce warranty repairs for the manufacturers. In almost all cases it kills the vehicles' true straight-line potential and is excessive. It can be tuned-out of the DME with a competent flash tune* I don't know as of yet who's been successful at doing that but several claim they can. It's something I will be tuning-out in my 6-spd M4 in the future for sure.

If that is what it is, it feels really weird. My hand was on the gear lever and I could feel something going on. Really never felt this before.

[spd974]

And by the way, this is only noticeable in Sport+ mode.

[SakhirM4]

Originally Posted by spd974

And by the way, this is only noticeable in Sport+ mode.

That's because there is no rev-matching.

[spd974]

Originally Posted by SakhirM4

That's because there is no rev-matching.

In sport +, I rev match when going down gears (from 4 to 3 for example).

But what I noticed is when going up in gear (from 5 to 6 for example).

When going up in gear, rev match would mean delay when you let go of the clutch instead of blipping the throttle when going down in gear.

[SakhirM4]

Originally Posted by spd974

In sport +, I rev match when going down gears (from 4 to 3 for example).

But what I noticed is when going up in gear (from 5 to 6 for example).

When going up in gear, rev match would mean delay when you let go of the clutch instead of blipping the throttle when going down in gear.

I meant that there is no auto rev-matching in sport +

[spd974]

Originally Posted by SakhirM4

I meant that there is no auto rev-matching in sport +

Correct!

But still, this slip feeling and somewhat loss of power is something I have never experienced before going up in gear.

Going down in gear, if you mess up, you get strong engine break.

But going up, you typically feel nothing so that is why I am still puzzled and not sure everything is ok with the car.

And I am sorry if I am not super clear. It is pretty hard to describe.

[DavidGP]

Originally Posted by spd974

Correct!

But still, this slip feeling and somewhat loss of power is something I have never experienced before going up in gear.

Going down in gear, if you mess up, you get strong engine break.

But going up, you typically feel nothing so that is why I am still puzzled and not sure everything is ok with the car.

And I am sorry if I am not super clear. It is pretty hard to describe.

Haha, yeah, I am really confused by your post. First its sleeping, now its slipping. When shifting up in Sport+ the car does not try to rev match the upshift. In any normal car with lots of torque and HP and a "grabby" clutch you will experience a jolt when upshifting and letting off the clutch. You dont notice it in Efficient or Sport because the car is rev matching the upshift to make it smoother. I think what you are experiencing is normal. Up and down shifting in sport+ is a little jerky because the clutch is doing its job.

[BIGW0RM]

MQUEEF?

[spd974]

Originally Posted by ILSMKU

MQUEEF?

So I just drove the car again and did more tests...

It only does it from 4 to 5 or 5 to 6 in Sport + mode.

ANd along with the slip feeling, I can hear a sound that goes with it. It sounds like a "fart" or a weird dog barking kind of. Very hard to explain.

Am I the only one?

[ashmostro]

This is entertaining. Sport+ causes gas! :P

[Arcades]

Originally Posted by ashmostro

This is entertaining. Sport+ causes gas! :P

Hey! To some of us cars are people too you know~

The noise is exhaust though. The F80/82 Is known for it.

[spd974]

Originally Posted by Arcades

Hey! To some of us cars are people too you know~

The noise is exhaust though. The F80/82 Is known for it.

Weird thing is that it does not seem to be coming from the exhaust.

[BIGW0RM]

Originally Posted by spd974

Weird thing is that it does not seem to be coming from the exhaust.

Go pro it bud.

[spd974]

Originally Posted by ILSMKU

Go pro it bud.

I will try to record it with my phone to show you guys.

[SROC3]

I have a 6MT and do not have this issue. Also - going from 5th to 6th should not have to be a fast shift.....unless you're trying to get your license revoked - 5th gear fast shift to 6th I'd imagine would only happen on an airplane runway or on the Salt Flats. Lol. If that's not what you meant, then a regular shift to 6th from 4th or 5th should not cause any form of slippage and engage smoothly. Looking forward to the gopro vid

[spd974]

Originally Posted by SROC3

I have a 6MT and do not have this issue. Also - going from 5th to 6th should not have to be a fast shift.....unless you're trying to get your license revoked - 5th gear fast shift to 6th I'd imagine would only happen on an airplane runway or on the Salt Flats. Lol. If that's not what you meant, then a regular shift to 6th from 4th or 5th should not cause any form of slippage and engage smoothly. Looking forward to the gopro vid

Hahah true! Don't worry, when I meant fast I meant letting go of the clutch a bit too fast. I am not going fast since I am still breaking the car in.

But again, to be honest with you, if I let go of the clutch like a grandpa (meaning extremely slowly), then it is smooth. If I let go a bit faster (I am not talking about dropping the clutch at all), then it does it.

The fact that you do not experience it worries me.

On a brand new car that is that expensive, I did not expect to have such an issue.