I bought my E92 M3 from a dealership as a 4-owner car out in La Habra about 14 months ago. I was always looking around for an E92 M3 with a DCT transmission. I was happy to find a simple black/black E92 M3 with decent miles and it was a competition with the carbon fiber roof. I was pretty stoked to pick this one up for myself.
After a few weeks of driving it I noticed that the car had a clunky sound in 1st gear. They called it the "cowbell" noise. It sounded like a cowbell getting hit, but only from a stand still. It sometimes happened in 2nd gear when I was slowing down.
This video explains it all, but it was basically the center support bearing. I heard two sounds. The first one was a cowbell noise, which was a big clunk. Then I heard something like sand moving around. Something was rubbing. My driveshaft was rubbing on my heat shield.
We also replaced the guibo or the "Flex Disk".
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I hope that this helps you figure out your issue. This completely got rid of the sound for me, plus the engagement from a stop to driving is much better. Thanks to Precision Dynamics for the install!