Hey has anybody ever ran solid motor mounts on a 72 chevelle malibu. My car is a 307 car and I put a 502\350 trans. I raced the car a bunch but the bell housing starting cracking over time and forced me to park the car. After talking to many people Ive decided the solid mounts were the problem and I m changing everything back over to stock rubber mounts. Ive been told by many racers that they run the heck out of there car on rubber mounts. The car has no cage and the 502 is a boat motor that is not to radical. Im just looking for any advice you guys can give me.

Until I put the new motor in I had a solid on the drivers side,rubber on the pass. side,and poly transmission mount, I now have 2 solid motor mounts and the poly trans mount. No problems yet. I would never run a solid trans mount. Do you have both aligning studs on the back of the block? and all the bolts holding the transmission to the block?

I run the poly mounts. I took a cracked solid mount out of the one side. For a lot of street driving the solids can develop cracks just from vibration. I have a poly at the trans also, and had the bolts come loose from vibration. I have to get the driveshaft balanced and run it again, but may switch the trans over to stock rubber.

Beer,
Solid mounts are fine as long as you dont run all three. If you run solid mounts on the engine, you need to have a rubber mount on the trans. There are hundreds of race cars running solid mounts with no problems.
On another note, when I first built my 67 Camero drag car, I cracked 2 TH400 bell housings in a month. Trans builder told me it was probably a driveshaft out of balance even though I could feel no vibrations up to almost 8000 rpm. I had a new driveshaft made and never broke another bellhousing ... just don't know ???

I think there must be a out-of-balance condition in the driveshaft also. I had a 400 Turbo that had a balance problem and it cracked right where the trans. cooler lines connected.