Okay sorry for not reading the 12 pages of posts but this is what I get out of it.. My car has been brought to the dealer for this problem 4 times now.let me first say that I know for a fact it is a rock stuck in the rotor shield ... It's common sense..
First time- they told me this is "normal m3 behavior" yea okay smd normal behavior... So I took it home and hoped it would go away...
Second time- they told me they don't know why I keep bringing it back because they can't fix it. I told them if be back when it gets worse
Third time- the tec swore he knew what it was. The e brake. They changed it guess what? Still dinging. Like a motherfuck at low speeds ..
Took it back for a fourth time they changed my rear brake pads.. Now I know what your thinking, this makes no sense & the only thing left to do is check my rock theory ..well sure enough they refused and I'm still with the problem .. Yep