RC Monster 8ight motor mount problem

Hello,

I recently purchased an RC Monster motor mount for my 8ight buggy. When I installed the Kyosho (46T) plastic spur gear on the center diff I noticed that the diff screws and the spur gear teeth rubbed on the motor mount. I attempted to shim the rear diff bearing back for more spur gear clearance away from the motor mount, but that ended up binding the driveline. I swapped between the stock steel spur and the plastic Kyosho gear about six times trying different shim configs and no shims before milling the motor mount on a lathe to allow clearance for the diff screws and spur gear teeth. I am a little disappointed with the motor mount, since additional work was needed. Most of the forum posts that I have read recommend using the plastic Kyosho spur gear.

Please advise if I missed something or if it was supposed to be shimmed another way.

Thanks