E46 M3 – “Clunking Noise” on Load Reversal

[vatkens]

I’m with BMW of North America, LLC. The M3 is a refined version BMW’s race cars. It is designed to provide optimum power and performance in a street legal package.

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. To achieve this maximum torsional rigidity, 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) the driver can receive an acoustic feedback, which can be interpreted as a “clunking or rattling” noise.

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.

If you have any questions, you can phone us at 800-831-1117.

[neil@domino.org]

Why do only some M3's do it then?

[The HACK]

Originally posted by neil@domino.org
Why do only some M3's do it then?

:dunno:

Every M3 I've ever driven (from E30 to E46) ALL exhibit the clunk.

[neil@domino.org]

Not going to argue with your experience, however, I'm in the process of trading my current M3 manual in for a new M3 with SMG 2.

I'd argue that my manual has +no clunk+ at all, so for the short period this topic will be interesting, lets believe that I am correct.

To ensure that I really want SMG 2 I've been on three test drives in three different cars. The newest 03 car that I took out [pre LED lights thought] clunked +really+ badly, even the salesman with me was embarressed. The others didn't clunk [or didn't as in my interpretation of clunk].

I've since heard of one other car that clunks as badly and went for a ride in it and it was the same as the car above. Whilst its great that BMW admit this is normal, its not so great if you are one of the suckers who gets a loud clunking car. I'm worried that the new car I get will be a clunker.

Neil.

[The HACK]

Not trying to argue with you, but I have also noticed that the clunking is relative to ambient temperature and also a specific shift pattern. It IS possible that the different time of the day you went to test drive the car could possibly have an effect on how much the SMG clunked.

Lastly, a lot of the clunking can be addressed with shift pattern and behavior. If you tend to like to do clutch dumps (like Stuka), the car will clunk in almost every single gear. If you feather your clutch and don't drive hard, your transmission will not clunk.

I guess we both have different experience wrt to the BMW transmission/driveline clunk. :dunno:

[in_d_haus]

Does that mean BMWs are Clunkers? :D :rofl:

[Stuka]

Originally posted by in_d_haus
Does that mean BMWs are Clunkers? :D :rofl:

Forgot about my clunker brigade?:drive: :bustingup :bigpimp:

Andy
02 M3 CB/Cloth SMG

[TGray5]

Originally posted by The HACK
snip..........
Lastly, a lot of the clunking can be addressed with shift pattern and behavior. If you tend to like to do clutch dumps (like Stuka), the car will clunk in almost every single gear. If you feather your clutch and don't drive hard, your transmission will not clunk

I guess we both have different experience wrt to the BMW transmission/driveline clunk. :dunno:

I also notice that smooth driving will minimize the clunk...and for someone new to SMG, being smooth is not easy. However, having said that, the first time I heard the clunk was after about 4 months of ownership, thus giving credence to the theory that it is due to the loosening up of the drivetrain.:dunno:

[psychik]

I’m with BMW of North America, LLC. The M3 is a refined version BMW’s race cars. It is designed to provide optimum power and performance in a street legal package.

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. To achieve this maximum torsional rigidity, 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) the driver can receive an acoustic feedback, which can be interpreted as a “clunking or rattling” noise.

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.

If you have any questions, you can phone us at 800-831-1117.

Hi,
is this clunking behavior attributed only to M3's? I have a similar issue in my '02 330i. When the car is cold (I try not to raise RPMs over 3000 until the temperature reaches optimal), I hear a clunking sound when I push the clutch in at around 2500 rpm while shifting from 1 to 2.
Is the 330i's drive train similar to M3, or do I have a different problem? I did take my car to a local NYC dealer, but they claim they couldn't reproduce that sound...

Thank you for any suggestions,
Oleg.