BAD grinding sound.....HELP!

[Marc Gallagher <mgallagher@Langan.com>]

Hi all,

Here's the story:

97 glx, 67,000 miles, z-eng s/c.

On the drive home today on Route 78 in Jersey, down shifted to 4th doing
about 70 to get in the passing lane.  As I let off the gas to shift back to
5th and start to let the clutch out I get a semi-loud clunk.  hmmm

Nothing for another 20 miles.  Then down shifting on the off ramp to 287,
while letting the clutch out a mutch more pronounced thumping sound.
Sounded something like if you stick a piece of wood in a fan while it is
ont.  Real fast, repeated thumping.  Not a gear grinding sound.  At first I
thought it was something stuck int eh wheel well rubbing the tire as I
turned ont he ramp.  I now hypothesize (sp?) that once the engine/fly
wheel/clutch was back to cruising speed the thunping stopped.

After checking the wheel well for a foreign (or broken) object, I tried to
create the sound in the driveway and was somewhat successful.  It seems to
happen when releasing the clutch, before the clutch/fly wheel/engine/tranny
all get sync'd together.  Again, it is a deep, rapid thumping,  Not at all
pleasent.

Any ideas before I schlep it over to the shop?

cheers,
marc