Well after I broke the 3rd rubber mount on my car I figure it's about time to install a poly one. I got the mount on and went for a drive, I cant believe the amount of road noise that increased. I knew it was going to be more but not this much, plus I have a new rattle in my dash somewhere now. Now I really dont care about the increase in noise or the rattle, it kinda goes along with the symphony of squeeks and other noise from my lcas and panhard rod and other poly components. But the thing I do care about is the slight vibe I get from anything over 75mph. I thought the prothane mount solved the poly tranny mount vibe issues, thats why I bought it. Anyone else getting this vibe from this brand mount or am I the only one?

I've been using the prothane mount for a while now. Yes, you do get more of the vibration transferred throughout the car since it is a harder unit than the rubber. On the other hand, my T5 feels like a rocks solid beast with this thing installed. Before, The shifter would be moving all over the place with the stock rubber mount which flexed all over the place.

poly rear trans mount is the only way to go. I broke 3 of the rubber ones in a week, and I put in the poly one that has the metal interlocking arms (so it cant rip apart) and its been working great for a year. I agree about vibration sucking, anything over 80 in my car and it feels like im driving a jackhammer.

I changed so much rear suspension stuff i dont know what gave me the more road noise and vibration, but my tranny feels solidly mounted to the car instead of moving aroun so i am pleased with using it.

whens the last time you had your driveshaft balanced?

One issue with some poly mounts is that they are a bit taller which raises the rear of the trans and slightly increases the angle between the driveshaft and the output shaft of the trans. The result is that the U-joint has to work a bit more and results in a vibration being felt at higher speeds. My solution was to add spacers between the trans crossmember and the frame to bring things closer together.

Pete

I know its not the ds because I never had any problems with the stock mounts vibrating. I've been up to 141mph without any vibes with the stock mounts. Plus, I have the JG1 ds.

Good idea, Im gonna try that. But I was told that the prothane mounts are the exact same height as the stock ones, I should've compared the two to double check

Probably stock new ones, I'd imagine though that the rubber mounts would compress more keeping the angle proper. With the prothane mount, it wouldn't compress as much and change the driveline angle. Just a guess.
I had my driveshaft re-ballanced and it came back with a lot less vibrations. At 80 mph, the center console would vibrate so much that my GPS would bounce off onto the passenger seat. Now it stays up there no problem up to at least 112 mph hehe.

instead of keeping that spacer between the mount and tranny and spacing the cross member lower, take out the spacer between the mount and tranny. i actually was told not to use that when i installed mine because of the same problem, the angle it puts the shaft at is to much.

"I know its not the ds because I never had any problems with the stock mounts vibrating. I've been up to 141mph without any vibes with the stock mounts. Plus, I have the JG1 ds."

Don't assume that. Your stock rubber mount was probably absorbing more vibrations than your current poly one(un-noticed vibrations become noticeable).