Hi
I'm looking for help to find whats causing a hollow thump sound from rear of my 728i. It mainly happens when going up hill and on bends and sometimes after stopping at traffic lights very quickly. Sometimes I wont hear it for a few days then suddenly it returns.

Have only got car back from garage but they could not find anything wrong. So would be grateful for any ideas on this.

Its a 728i 1998 with 69,000 on clock and in UK.

Hugh