I tried searching, but did not find anything really matching what my car is doing. My car is shaking pretty violently in reverse and under overrun only.

I'm thinking it is a mount somewhere in the driveline, but am not sure which one it could be, as I just got the car and am not that familiar with the driveline mounting yet.

Does anyone know which one would cause severe juddering under reverse torque, but operate smoothly while accelerating forward?

 

Engine mounts.

 

I had a car that was shuddering when applying the clutch and it was due to fluid on the clutch disc and was worse in reverse because we tend to "feather the clutch" the most in reverse. I'd suggest that you check the clutch inspection hole in the lower bell housing to see if there's evidence of failing rubber clutch disc. Could also be loose or failed transmission mount. What did you mean by "overrun"?

 

By overrun I mean on when downshifting and engine braking. Even double clutching and matching revs it does this. Are the engine and transaxle mounts visible with the car up in the air? Is there a diagnostic procedure to check one vs the other?

 

Bad torque tube bearings will do that. Get louder while decelerating or in reverse while ok while accelerating.

 

After some more testing, it appears that coasting in gear is fine, it's the initial application of negative torque that upsets the driveline.

By my count there are 2 engine mounts and one transaxle mount. Anything I'm missing?

-Tom

 

I have the same issue when downshifting into second gear. I filled my transmission mount with sikaflex but it did not help much. I guess I have the original motor mounts and these are 23 years old now and have probably seen their best days.

 

the bad motor mounts will definitely cause problems, as will a bad trans mount - look at any of the FAQs that tell you how to change, a collapsed mount is pretty obvious. Don't use the cheap mounts, they don't last and don't work well.

 

alsoI have seen the rubber center on a stock factory clutch being broken causing this, and a bad ring and pinion as well on another vehicle. put car in gear, handbrake off, lift up rear or put on a 4 wheel post, remove transaxle coupler inspection seal, grab coupler by hand and try to turn left and right. If it moves at all when in gear, you need a new clutch disc my friend. PResto

 

The clutch and motor mounts are pretty new. Also, while smogging the car yesterday, I didn't see any movement of the motor when on the dyno rollers between shifts or during transitions from on to off throttle. I suppose the last thing would be the transaxle mount. The car already has LR semi solid motor mounts, I figure I may as well get the semi-solid transaxle mounts as well unless any of you want to talk me out of it.

 

then it just may be your ring and pinion.

 

maybe you somehow assembled the ultra mounts incorrectly as a possibility besides the ring and pinion? did you try the test i mentioned above?

 

There's a centerforce clutch that the PO installed in the car so there shouldn't be a rubber hub to fail. I think it's the transaxle mount...it's the only mount that has yet to be replaced.

 

ok .. but do you have proof that the clutch was replaced? you can't trust anybody. jack up the car and wiggle the transaxle, if mount is toast you will have a lot of movement.

 

If anyone ever looks this up, it was a loose bellhousing...tightening the bolts cured it. Hope this helps someone in the future.