Today I replaced the rear transmission mount. Since I purchased the car in February I had occassionally ehard thumping noises when I went over bumps and dips. Checked for similar information here at camaroz28.com and decided it was a broken rear transmission mount. I decided on the GM replacement mount, PN 22201140, because of the possibility of vibration when using a polyurethane mount. There has been talk about a difference in height of the newer mounts and what to do to compensate for the change in pinion angle. I came across a different concern. When inspecting the underside of teh car the first time I changed oil I noticed the exhaust was very close to the X-Brace and thought this to be strange but it did not seem to be a problem. After I removed the original rear mount I set it next to the new rear mount and discovered there was at least a 1/2" difference in height plus the original rear mount was not broken. After I installed the new rear mount I realized the exhaust had been too close to the X-Brace. The thumping noise was most likely coming from the exhaust hitting the X-Bracket. If I did not want to spend the money on a new rear mount I could have been cured the problem by adding spacers between the X-Brace and the body. I took pictures. If anyone would like to see the difference just pmail me and I will send them. If someone has a page they would like to add these pictures to, let me know and I will send thetm to you. Time to change clothes and test the new rear mount.

 

just because it doesn't look broke doesn't mean it wasn't worn out.

i iinstalled the poly mount and noticed very minimal vibration, and i already had poly motor mounts and poly bushings on most of the suspension.

 

having the extra space between the exhaust and the X-Brace makes me feel better. I tested it and can't get it to thump. If it breaks I will try the poly mount.

 

the rear mount is the only mount.

and your list, of posi, and 2.73 kinda go with the LT1 and the 4L60E
and listing your stock rear mount is just weird

 

The rear mount is listed as a change (correction / repair) and not meant to be something I necessarily added for performance. When I research things I want to add or change I also look at the users signatures to see what they have done. In the case of the rear mount there are three choices, an older and lower in height mount if you can find one, a poly mount, and the newer and taller (PN 22201140) mount. Hopefully this can help a newby like me make an decision. Listening (and reading) to Injuneer and Shoebox has helped me tons. Hopefully we are all here to share information and be helpful to each other.

 

A search is much more effective for information then a signature is.

By your reasoning everyone should put their new oil filter numbers, replacement shocks, window motors, door seals, and the list goes on.
But I'm not saying your cant, its your sig. and I dont mean to question it. jsut struck me as odd.