A few months of running the ZZP poly motor mounts, I was getting this horrible squeaking whenever I'd hit bumps or switch from forward to reverse, or vice versa. The squeaking over bumps to me didn't seem that it could ever be pinned to motor mounts, but after totally investigating the root of the noise, that's what it turned out to be. I also had some nasty engine vibrations sitting at a stoplight, especially if there was a lot of load on the engine i.e. heated seat on, rear defrost on, etc. Since I knew I had poly mounts, and they were going to transmit vibration, I didn't really worry about it, but the squeak had to be corrected to save my sanity. I first sprayed them with WD-40, and this helped for about a day.

The poly cubes are just a hair wider than the metal spacer tube that goes thru them, so when the dogbones are fully tightened, it pinches them so tight they can't slide at all. Mine actually had impressions in the poly where the dogbone squeezed into them. So I took out the trusty ol' belt sander and shaved about 0.050" off of each side, so the metal tube protruded about 0.010" on each side. Reinstalled them, and not only is the squeaking totally gone, but a good 75% of the nasty engine vibrations vanished as well! It's extremely nice now! Still slightly more vibration than the stock rubber inserts, but far and away better than it was!

Anyone with this problem might want to check theirs too, and if there's any impressions in that poly cube, follow the procedure above. Worked fantastic for me!