[cdigerlando]

I'm getting ready to redo my motor mounts so they are more heavy duty. The liquid filled rubber stock mounts probably just won't do for the new built motor. I've purchased some high strength urethane casting compound and some mold release spray from McMaster-Carr. It is the less pliable 94A compound. For starters I cut away most of the rubber from my most damaged mount. It was torn and had no more fluid in it. I then blow torched and burned away the remaining rubber. The next thing I will do is wire brush the remaining carbon to expose the metal. I may try to etch or otherwise better prepare the metal for the urethane. I'll look at the paperwork on the urethane casting compound to see the best way to do this.

I don't want to rely solely on the urethane bonding with the metal for connection to the mount. I thought of drilling holes in the top and bottom of the mount to help "attach" the urethane filler to the top and bottom circular mount plates. I'm also considering installing some through bolts to better reinforce the mount to the top and bottom plates. I would screw these bolts in before the mount was installed so that they would only stress when the engine twists and yanks on the mount, giving it extra support. I am thinking of drilling 8 holes radially around the top mount and 8 holes radially around the bottom part. Then tapping threads through every other hole in the bottom to accept the bolts. Then I will cut a piece of PVC to match the diameter of the mount and the height. I'll spray the interior of the PVC with release compound and the 4 through bolts. Then I'll bolt everything together. I'll then mix the compound and inject it through one of the 4 holes on the top, allowing the urethane to bleed a bit through the holes so it better attaches to the top and bottom plates. When everything cures I'll cut away and remove the PVC circular mold and unscrew the bolts. I'll then drill out the bolt holes a bit so that the bolts don't touch the urethane and help to disconnect it from the mount. Then I'll loosely re-attach the bolts, so when the engine twists they can stop the motor from stressing the urethane too much.

Let me know what you think. I know that Mike (LAN) was also thinking of casting his own mounts.