After having spent a month or so trying to kill all the tail end rattles in this IPD'd 245 rear end, along with a sloppy rear seat, tail gate, and used factory dog gate, I quite by accident found the final MONSTER thunk and rattle!

On occasion, the rear muffler would slip out of the driver side mount... which resulted in the exhaust hitting on the passenger side with a thunk. When I would re-connect the driver side hanger, the thunk would go away, but a high frequency rattle would appear at around 2500 RPM. Well, while I was making sure the driver side rear exhaust mount would stay put, I went to remove the rubber coupler pin that bolts into the frame with a 17mm wrench... that sucker was loose by three full turns and I was able to remove it by hand. Note that it also holds the exhaust heat shield against the frame rail!

To keep the rubber mount from slipping off the end of the frame mounted pin, I threaded it at 10x1.25 and added a lock nut to ensure the rubber hanger won't slip off again. That fixed the hanger slipping off, and tightening the mounting pin against the frame rail cured the final mystery rattle.

Sure with urethane bushings, there are a few sub-30HZ thunks to be heard, but at least the dang bumble bee noises have been eliminated!

Just something else to look for while noise trouble shooting!

jorrell
--
92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!