after driving about an 1/2 hr or so the passenger side rear develops kind of "thumping" noise. has new shocks/struts. tires/wheels are fine. nothing in trunk. mechanic cant find it
the cat and the muffler seem ok. Its NOT a rattle.
could it be something IN the muffler?

help!!

thanks,

nancy

 

If it hasn't been done, switch tires from side to side or front to rear to see if any change.

 

Is the thumping noise consistent with speed or is it heard over bumps? Had the rear differential mount been checked?