Did anybody change the DCT clutch?

[OM VT3]

Originally Posted by Sneaky Pete

I though OEM was around $2300?

Sorry you're right not sure why I was thinking 4k

[RomanK]

Originally Posted by DrFerry

The DCT jerk between shifts and even down shifts can be mitigated and improved by:

A) Selecting the S2 or D2 shift programs using the button in front of the DCT shift lever.

b) Lifting the accelerator pedal very slightly (1/8th of an inch or so) during the up shifts.

See image below:

_

Please, don't think that i am full newbee. I know it very good. I just can't explain to you on the good english what I mean.

I mean not the hard shifting... I mean not so good shifting under very small throttle in hard traffic when it require 1-2-3 gears in D mode. DOWNshifting i mean. I think it is connected with my clutch... what do you think about it

?

[dparm]

Originally Posted by DrFerry

The DCT jerk between shifts and even down shifts can be mitigated and improved by:

A) Selecting the S2 or D2 shift programs using the button in front of the DCT shift lever.

b) Lifting the accelerator pedal very slightly (1/8th of an inch or so) during the up shifts.

See image below:

_

Lifting will actually make it worse, as the mechatronics unit may decide not to shift if you change the throttle input. This is not an SMG -- you do not need to lift slightly to smooth shifts out.

The DCT will be slightly jerky in higher DriveLogic modes. This is because it is using the clutches more aggressively and not slipping them as much, which gives a faster shift (for spirited driving). If this isn't to a driver's liking, they can run it in a lower DriveLogic mode and it will be nearly seamless. The DCT should not be lurching -- that would be a sign of a problem, which it seems like the poster you quoted is claiming.

[dparm]

Originally Posted by DrFerry

dparm,

I'm not suggesting a big, full lift out off the gas - as many do with a manual. I suggested a 1/8th of an inch lift in my post above. That technique works very well to smooth out (reduce jerk) DCT shifting in normal to aggressive style driving, and especially with DCT WOT shifting.

Okay, thank you for clarifying. My point remains that if you want the smooth operation, run a lower DriveLogic mode and it feels like a normal slushbox automatic.

I almost never used anything below mode 5 since I prefer the slight snap feel when driving harder -- it's a sporty car after all. I guess I am confused why people would want the number feel from a car like this...those sporty attributes are why I bought it, but I guess some people have different priorities.

If OP is noticing the M-DCT's behavior suddenly changing, then something is clearly wrong. If his is operating normally, and he doesn't like the feel of the M-DCT, I feel like that would be something you'd notice right away on a test drive...

[RomanK]

Originally Posted by DrFerry

Other than asking what shift logic program are you using (D5?) I can't really comment anymore. I have not experienced the "not so good shifting under very small throttle in hard traffic, when 1-2-3 gears are required in D mode. My D mode is smooth especially in D1 (snow mode), D2 and D3 shift logic programs.

Are you running the latest 240E DME software and/or some kind of Engine or DCT software flash tune?

Ok, I use standart 220E DME software and DCT GTS software.

I am using all the programs and D2 and D3 and D4 and D5. But it does not matter on what I tried to explain. I know how it influense on car feeling..

I feel that my DCT gearbox works properly and I can it understand because I know
mechanism DCT and I know how it works.

I am Russian speaking guy and I can't explain so good in English my feelings of working of my dct and clutches. I will try one more time.

My feelings is that my clutches switchs on not so on time how it should be on new car. I can explain it for example if I run manual gear box with damaged clutch that I need to release my clutch pedal more to start moving than it would be on new clutch... understand? So the feelings the same on DCT in D mode, I feels that clutch should be already connected with flywheel at one moment but it connects a little bit later and I feel the small kick because my flywheel already turns more faster than should turn at the connecting moment. So other words - my clutches delay.

So my feels that my clutches should be adapted... Maybe I should did it after the coding DCT GTS software? I did not it. Maybe it is a reason.

And I repeat, dct works awesome, there is no big problem at all. The little inconvenience only on small speed and low throttle in big city traffic.

I used my car without any problems... but yesterday I tried the same car with the same miliage of my friend and I understand that his car more smoother at small speeds and low gears. The difference between our cars is - his car has BPM DME software from Mike Benvo, that is all.

Very sorry for my English...

[deansbimmer]

I think you answered your own question by considering the DCT clutch adaptations being cleared and relearned using BMW software. Try that first.

[RomanK]

Guys, I think I found my problem.

Can you tell, do you know any tuning flanges of differential to solve the problem of LEFT OEM flange?

My problem here:

Too big backlash with a clunk... I heared that there is often problem and there are a tuning solution of it... Does somebody know?

[deansbimmer]

It is normal for the differential output to have exaggerated radial play. Every M3 I've worked on has had a lot of play there. See technical bulletin from BMW below.

It is also normal for the axle shaft to slide back and forth a slight amount.

Neither of those are likely to be causing any significant noises you describe. Unless the small amount of noise that might be generated in certain driving scenarios is causing you great distress.

"Customer may complain of a drivetrain rattle or knocking noise during a load change, e.g. 1st to 2nd gearshift at low engine speed, coming from the rear axle area. Further drivetrain checks reveal that the right side rear axle output flange appears to have more play (approximately 0.5mm to almost 1mm) when compared to the left side output flange. INFORMATION
The radial play on the right side rear axle flange is a normal design characteristic of the new M differential lock style rear axle used on E46 M3 models. Therefore an M3 differential should not be replaced due to a difference in play (when comparing left to right side differential output flange play) since this will not eliminate a drivetrain rattle or knocking noise.
IMPORTANT: In order to transmit engine torque to the rear wheels instantaneously, without any time lag, the whole M3 power train was designed with maximum torsional rigidity. Consequently, the flywheel mass and its damping capability has been reduced to a minimum. As a result, during an abrupt torque transfer (e.g. 1st to 2nd gearshift at low engine speeds) driver receives an acoustic feedback, which can be interpreted as a "clunking or rattling" noise. This characteristic is common in many high performance vehicles. Activation of the "Sport Mode" offers an additional increase in driving dynamics. As a result, acoustic feedback from the power train may be even more pronounced. The acoustic feedback characteristic is not a symptom of a failure, and does not compromise long-term reliability of drivetrain components (clutch, transmission, differential), nor does it adversely affect performance of the vehicle. WARRANTY INFORMATION
For information only."

[RomanK]

I have big bump and kick and clunk from rear subframe when I push/release throttle pedal.

It is not something from DCT because clunk from rear subframe exactly.

I have solid subframe and differential bushings.
I have new flex dics, I have normal driveshaft, I have new driveshaft constant velocity.
I have new right half axel.

One problem that I have is a backlash from left flange... I think it is too big. My diff master investigated all rear part of my car and nothing else found there...

Don't know what I should change to solve my problem.

[RomanK]

"Customer may complain of a drivetrain rattle or knocking noise during a load change, e.g. 1st to 2nd gearshift at low engine speed, coming from the rear axle area. Further drivetrain checks reveal that the right side rear axle output flange appears to have more play (approximately 0.5mm to almost 1mm) when compared to the left side output flange. INFORMATION
The radial play on the right side rear axle flange is a normal design characteristic of the new M differential lock style rear axle used on E46 M3 models. Therefore an M3 differential should not be replaced due to a difference in play (when comparing left to right side differential output flange play) since this will not eliminate a drivetrain rattle or knocking noise.
IMPORTANT: In order to transmit engine torque to the rear wheels instantaneously, without any time lag, the whole M3 power train was designed with maximum torsional rigidity. Consequently, the flywheel mass and its damping capability has been reduced to a minimum. As a result, during an abrupt torque transfer (e.g. 1st to 2nd gearshift at low engine speeds) driver receives an acoustic feedback, which can be interpreted as a "clunking or rattling" noise. This characteristic is common in many high performance vehicles. Activation of the "Sport Mode" offers an additional increase in driving dynamics. As a result, acoustic feedback from the power train may be even more pronounced. The acoustic feedback characteristic is not a symptom of a failure, and does not compromise long-term reliability of drivetrain components (clutch, transmission, differential), nor does it adversely affect performance of the vehicle. WARRANTY INFORMATION
For information only."

As for this. I totally understand what this quote is talking about. I understand it.. But I have another. I have big kick and bump, not from gearshift but just pushing and releasing of throttle pedal on any gear...

[RomanK]

Originally Posted by RomanK

Can you tell, do you know any tuning flanges of differential to solve the problem of LEFT OEM flange?

Nobody heared about it?

[Patrón]

Originally Posted by RomanK

Nobody heared about it?

do you by chance have aftermarket swaybars?

[deansbimmer]

Originally Posted by RomanK

Nobody heared about it?

The left flange? Nothing has been made aftermarket that I'm aware of, probably because it's an aspect of design. If yours has worn excessively then replacing the diff or rebuilding it with new parts will eliminate the play that has come with age and wear.

[BPMSport]

You do not need to readapt after this kind of software change because the physical characteristics have not changed. Adaption is usually carried out in the event of a hardware change - such as new clutch, pressure sensors, mechatronics unit, etc..

[GORDON.M3]

Originally Posted by Mike Benvo

You do not need to readapt after this kind of software change because the physical characteristics have not changed. Adaption is usually carried out in the event of a hardware change - such as new clutch, pressure sensors, mechatronics unit, etc..

+1, it is clearly mentioned that DCT adaption should be only relearned when there is physical hardware change done to the transmission. Sure some people do it when fluids are changed but not recommended.

[p4tr0n17]

So glad I found this thread!! Suffering the same issue as RomanK, slight bump when coming on/off the acceleration in lower gears/rpms.

Did you find a solution?