Noise: rear end.C5
 

After a dyno tune a clunking sound became noticeable and is now not annoyance but a concern as the car is scheduled for a track day Sat. My C4 has clinking sounds and the axle u joints were replaced to resolve that issue. The C5 sounds a bit more chunkier than the C4 clinking. Seems the sounds are reduced under slight acceleration. Any of you drivers or technicians have any thoughts. Thanks.

could be a ton of things. check all the bolts in the rear suspension and brakes for tightness.

Check the spindle nuts on the rear wheels. They are known to come loose once in awhile. I've had to tighten mine a couple times.

Loosen rear spindle nuts, popaxle ends in, lube axle splines and retighten nuts to spec. Fixed noise on mine.