rburt07 — Your report makes me think of another possibility. "Bells" implies metal-on-metal contact. Under that fiberboard spare wheel cover in the trunk, my anti-theft wheel nut adapter socket is attached to the wrench by a plastic cable tie. If the adapter is badly positioned, it could knock against the wrench and make a ringing sound on bumps.

Noni — Do you have anti-theft wheel nuts? If so, check out the above.

Stan