Clunk sound when decelerating - what is it?

[FatRear08]

So I’ve been getting this creak/light thud, usually just one, upon braking, downshifting while slowing down, and sometimes on acceleration usually from a stop. It’s not the familiar creaking from the door seals, but a more solid single creak from the rear of the car and doesn’t happen during constant speed. If I slow down or accelerate very easily, most of the time I won’t hear it. Car was in shop last week getting suspension done and everything looked good. Mechanically the car drives perfect. Anyone else experience this?

[ArieArie]

Originally Posted by FatRear08

So I’ve been getting this creak/light thud, usually just one, upon braking, downshifting while slowing down, and sometimes on acceleration usually from a stop. It’s not the familiar creaking from the door seals, but a more solid single creak from the rear of the car and doesn’t happen during constant speed. If I slow down or accelerate very easily, most of the time I won’t hear it. Car was in shop last week getting suspension done and everything looked good. Mechanically the car drives perfect. Anyone else experience this?

Something loose in the trunk or trunk compartment (where the compressor hides)?

[FatRear08]

All is secure in and around there.

[ArieArie]

Originally Posted by FatRear08

All is secure in and around there.

Try driving with the rear seats down, maybe it will help in locating the sound, or maybe it is part of the seat mechanism?

[FatRear08]

I’ll give that a try thanks! Never thought of the seats.

[Marshman222]

After the most recent software update (Nov 2017), I have the same exact issue in my MY '17 F80 Competition package M3. It happens when I'm braking, right before the downshift to 1st gear, but not during the shift. It makes this weird, soft 'clunk" sound when decelerating. It almost sounds like I have something in my trunk that's lightly bumping against the wall. I took everything out of the back of my car and messed with the seats, the sound still happens. When I play the radio, I can hardly hear it, but when I turn the radio off it's definitely noticeable.

Is this a normal sound, or should I bring it in to the dealership?

Also no issues on my last inspection. Let me know what you find out!

[FatRear08]

So far I haven’t found anything wrong. Was just in for a ride height adjustment 2 days ago and the boys said everything looked good. As I said in the first post, Car drives and runs 100 pct so for now I’m chalking it up to just another creak. I can live with it.

[theroadrunner]

DCT? mine will make a slight clunk/thud when downshifting from 3rd to 2nd or 2nd to 1st in D1 when cold, but never happens after its warmed up nor on acceleration.

[FatRear08]

Mine is 6MT and happens cold and warm. Who the F knows....

[jzmundy]

This actually just started happening to me as well. Ticked over 3000 miles this weekend and we are having much cooler weather. Not sure if there's a correlation...

[Celestion]

This is a normal noise for the 6mt. It may or may not also be normal for the DCT.

[FatRear08]

Finally got to the bottom of it. Center brace bolts weren’t torqued down. Tightened up and the creak/thud is gone.

[2jssepa]

Had same. Found three loose bolts in rear suspension. Re-torgued and all is fine.
BTW - had same issue 5k km's ago and dealer took 10 days to find it and correct it.

[damageprone]

Originally Posted by FatRear08

Finally got to the bottom of it. Center brace bolts weren’t torqued down. Tightened up and the creak/thud is gone.

Could you take a photo of this center brace so I could check mine? I have a DCT that has a slight thud when decelerating, but the general consensus is that it is normal.

[FatRear08]

Cars back on the ground, but google f80 M3 undercarriage and hit first pic. It’s the brace ahead of the resonator.

[rfeener86]

Bought my car in April in Munich (ED). Its done it since she left the factory. Yes it’s weird but so far with 4200 miles there have been no problems. Its ALWAYS makes the clunk when I begin driving in reverse. I haven’t cared enough to bring it to the dealers attention. Let us know what you find

[Andrew30azs]

Originally Posted by rfeener86

Bought my car in April in Munich (ED). Its done it since she left the factory. Yes it’s weird but so far with 4200 miles there have been no problems. Its ALWAYS makes the clunk when I begin driving in reverse. I haven’t cared enough to bring it to the dealers attention. Let us know what you find

My car make clunk noise on reverse too specially under load uphill

[gezed32]

mines DCT and i feel it sometimes too, i think its probably some slack in the driveline which is probably normal

[Andrew30azs]

Originally Posted by gezed32

mines DCT and i feel it sometimes too, i think its probably some slack in the driveline which is probably normal

Yesterday I tried to park my car uphill on reverse when I let off the gas I heard some buck , slack on my driveline , it was like three times . Do you have same thing ?

[BimmerDimmer6]

Trade it in / can't be good

[AndyLu]

I believe it's your differential. Our cars have some loud ass diffs.

[Andrew30azs]

Today I experienced something what I never had before after hard driving on manual paddle shifts i was trying to park my car uphill my driveway . And I heard some loud thud on the back then I’m trying to go forward and reverse again trying to repeat that noise I didn’t hear anything . What this could be ?


Day after I did same thing in the morning (no noises ) after work I drive pretty hard and it’s was the same thud noise on my uphill driveway (loud thud)