Bloody Cow Bell Noise Solved
Just in case know one else has found the cure, i did yesterday.
It wasn't pebbles.
That bloody cow bell noise is the passenger break guard. I used my trusty poking device 'old billiard cue' and pushed it back away from the disc quite firmly. I found with mine in particular, it was pinging off the disc at about 5 o'clock, i.e third the way round clockwise. I got the Mrs to drive on idle, backwards and forwards in an empty quiet car park and i spotted the problem straight away.
Solved. Was driving me nuts. A new M3 that sounds like it has a knackered exhaust.
I'm confident that will solve the pain for many of you. Actually glad, so many people had the same problem and i wasn't alone as BMW were no help at all. Can't replicate..........the norm.