Vibration from below.......

[luckycat]

My 87' 325IC has aquired a new and exciting vibration! When I accelerate quickly, I mean really on it, a loud thumping can be heard from beneath the car. I recently replaced the clutch (3000 miles) and replaced the entire drive shaft last year with a low milage used one. I have not had the time to pull the drive shaft back out to inspect it, but it seems solid. Normal driving is fine.
Could I have reassembled the drive shaft incorrectly? Any thoughts???

Thanks! Jim

[Trob]

I just put a tranny in my ix and it's doing the same thing at slow speeds. I think it's a heat shield but I have'nt had the time to take it in and have it checked out.

[bad man working]

Sounds like a prop shaft fault to me check the front rubber coupling and the centre mount