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Discussion Starter #1
Hey all, had a sudden onset of terrible rear end clunking/vibration on my new to me M3. Didn't go very far with it happening, maybe a few hundred yards. Anytime I try to get the car moving, let off the clutch, the rear end vibrates like crazy and I have the mechanical sympathy to not try any further. Reverse seems to be a lot better with an initial clunk but nothing further.

Unfortunately I was in the process of driving the car home (from the purchase) when it happened so I was without any tools or ability to really do any investigating. Therefore the car is at a random shop, 8 hours away from home until it's fixed. I also very seriously doubt that the PO was trying to cover anything up prior to selling and that this is just unfortunate timing on my part with a 20 year old car.

From some preliminary research it sounds like it could be the rear diff bushings as it kind of seemed like shifts were a little clunky prior to the sudden bad vibration onset.


I also saw that the rear subframe could be a culprit but it was reinforced within the past year or two with very little mileage added since, so I doubt that's the issue.



Any other input would be greatly appreciated.

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Could be tires, rear suspension or bushings, driveshaft, guibo, csb or differential. Needs to be inspected. If the car sat for a while I'd start with checking for flat spots on the tires

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Discussion Starter #3
Could be tires, rear suspension or bushings, driveshaft, guibo, csb or differential. Needs to be inspected. If the car sat for a while I'd start with checking for flat spots on the tires

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Definitely not the tires, vibration/thumping starts as soon as letting off the clutch and persists.

Guibo and a bunch of other rear end parts were also replaced recently so unlikely to be them either. But the car is en route to a shop so hopefully they'll be able to do all the diagnosing necessary.

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Discussion Starter #5
PPI was done, not by me, but the car was sold on Bring a Trailer and was presented as such.

Turns out the bolt that holds the front of the differential in to the bushing backed out because the threads were messed up. Nothing that anyone could realistically expect to find on a PPI or know about prior.

Thanks for the input though!

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