Originally Posted by mkoesel
Guys - here is what caused my "cowbell".
There's no way I'd have found this if I (we, actually) hadn't had the car on a lift and been able to shake the hell out of everthing under the car, and then been able to visually inspect it all to track it down.
And, it could very well be that there are other exhaust clamps, hangers, etc., that could cause the same thing, some of them perhaps hidden even better than mine was.
I believe your issue would be a vibration noise rather than the cowbell noise that goes clunk clunk clunk (from the rear wheel) as you move slowly.
However, I did see that thread you posted. That's scary that the hardware BMW is using would breaks so easy!!