I am experiencing a drive shaft vibration at about 55mph. The car seems fine at all other speeds. There is no noise from the u-joints or anything else when accelerating or braking.
You can actually feel the drive shaft (lightly) hitting the underside of the car if you place your hand on the transmission tunnel. The support bearing appears to be in good shape (tight and smooth)as do the u-joints (no play). I did replace the rubber donut for the support bearing and this seems to have made some inprovement.

I'm suspecting an out of balance drive shaft. Any ideas?

Jan 9 - Thanks for the replies, but guess what? I can't BELIEVE that I forgot to mention that I replaced both of the motor mounts and the tranny mount when I replaced the bearing donut!

I wrestled with drive train noise for some time, did the donut and bearing thing, tailshaft bushing then finally the tranny mount. That did it! Cheap and easy to do. My noise was more like an intermittent rumble or vibration that could be felt on the tunnel but it was not like anything hitting or striking the underside. It was dependent on speed but even that varied but always over 45 mph.
Drive shaft should not ever be out of balance unless it was damaged in some way.

Did you check the tranny mount? I had a similar problem after replacing all Drive shaft components and the tranny mount was toast. Did the trick to stop the vibration.
Good Luck.
Mike

I dont know but....

I have a similar but worse problem. My u-joint is completley shot, the needle bearings are all gone, it has a ton of play, and probally will snap soon.

Obviously, I am hoping to replace it before it snaps... that rubber doughnut you replaced, mine is old and i want to repalce that too. What is it actually called so I know what to have the brain dead parts guy look up?


Thanks, Brian

Brian -

I got mine through IPD. It's called a rubber center mount for the support bearing and sells for $12.50. The old unit was cracked and probably the original. The new unit feels substantially firmer.

If I had it to do over, I would also replace the center support bearing while I had everything apart. Although it seemed tight and in good shape, there has to be a chance that this bearing what is causing my problem. I'll probably end up replacing it before this little adventure is over!

- Curt