Crazy vibration after trans mounts

[gburk]

Hey guys,

I have a 90' 325is and today I installed 95a poly garagetastic transmission mounts and have a crazy vibration now (closer to a shaking feeling dependent on engine rpm). I installed matching motor mounts the other day with no issues.

The problem happens both in neutral and in gear, however it's definitely worse under load. It seems to start around 2500 rpm and smooths out quite a bit in 3rd gear. I have not tested in higher gears as I am afraid to break something further.

I was feeling a bit of vibration in my seat on the highway from about 60-70 mph prior to the new mounts but thought maybe the rear wheels were out of balance. The driveshaft, csb, and guibo were replaced somewhat recently and I don't think they are causing my issue because it happens when out of gear as well.

Clutch was also replaced recently, is it possible something is out of balance?

Any insight would be greatly appreciated!

[uturn]

I installed 95a poly..... I installed matching motor mounts....

Factory is ~55a to soak up some vibrations. Going harder transmits more of your drive train noise.

[Elysian]

That high a durometer is going to transmit a lot of vibration from the engine to the body. Don't recommend that on a street car, unless you're okay with more noise and vibration.

[gburk]

Factory is ~55a to soak up some vibrations. Going harder transmits more of your drive train noise.

That high a durometer is going to transmit a lot of vibration from the engine to the body. Don't recommend that on a street car, unless you're okay with more noise and vibration.

I expected vibration but the car almost feels unsafe to drive with the amount of feedback I’m getting. It literally is shaking the cabin. I drove a friends s52 swapped e30 with solid mounts and had nowhere near this feeling. It leads me to believe something else could be wrong.

[dude8383]

Swap them out... takes just a few minutes to do it (well minus jacking the car up and such). Not only that it happened right AFTER you changed them.

[gburk]

Swap them out... takes just a few minutes to do it (well minus jacking the car up and such). Not only that it happened right AFTER you changed them.

Swapping them is easy, I just suspected that maybe the stock mounts were covering up another issue that the poly mounts may have revealed.

[dude8383]

You would have felt that long ago. A bad flywheel or pressure plate or whatever driveline vibration would certainly present itself even through rubber mounts. The 95a is pretty firm :up:

[gburk]

You would have felt that long ago. A bad flywheel or pressure plate or whatever driveline vibration would certainly present itself even through rubber mounts. The 95a is pretty firm :up:

I sure hope so. The car is also very new to me but I still think I would've felt it before.

Let's hope you're right!