[NoVa-Corvairs] strange noise

[Daniel Goldberg]

The honeymoon is over ...

There is a steady "whump, whump" coming from the rear of my Corsa.  The sound comes on when the car is in gear and I am accelerating -- no noise when I'm coasting in or out of gear, so [I think] that rules out a bum wheel bearing.  There is also no noise when I spin the wheels by hand with the rear in the air -- in fact, I have yet to duplicate the sound with the car not in motion.

Everthing underneath seems tight and in place.  Also, the transaxle is full of new gear oil.

Any ideas?