I just installed a new rock on 4l60e and the poly mount. At normal speeds the car feels great, but at wot I can feel a lot of vibration. Is this possibly just the new mount or something worse? Anyone with the poly mount please chime in!

 

I had one in my car for a day, the vibration drove me nuckin futs. I put the stocker back in - problem solved.

 

Thanks for the info. I was hoping that it was just that damn mount. If I can't adjust to it, it will be out of there soon! I'm kind of picky about rattles and annoying crap like that so I'm sure it will be gone.

 

i installed one and never felt vibration, you sure you correctly torqued the mount?

 

mine only vibrates when im on the freeway and tranny is in overdrive...every poly mount affects every car different for some reason dont know why either.

 

I'm a fan of a single poly mount for the motor. It kills most of the twisting w/o causing nearly as much cabin vibration as most people get from a poly trans mount.

 

The key here is to not use poly mounts at all 3 engine and trans mounting locations. We have installed dozens of the poly mounts with no adverse complaints. Most of the time we see complaints is when stiff mounts are used at the engine and trans. Besides, using a poly mount at the trans and engine does not provide the trans case enough flex and will most likely crack it, worse in high h/p apps, but seen it in low h/p apps as well.
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Do you have poly motor mounts as well? I heard somewhere that if you have both of them that the trans mount might vibrate. At least that is what i heard.