Transmission mounts - pic

[boz42]

Cars are more forgiving that 4x4's. They do not have an extra 100-200 pounds hanging off the tail off the transmission. If you mix poly & rubber you run a risk of breaking a bellhousing off the trans. An engine & trans need to torque at near the same rate. If the trans had rubber & the engine had poly the transmission could try to torque further than the engine. The weak piont between the two is the bellhousing. The same princapal applies to building custom engine & trans mounts. All the bushings need to be inboard (meaning close to the engine or trans,) or outboard meaning near the frame.

Of course the greater the horsepower/torque the engine produces the greater the impact mixing poly & rubber mounts can have. In a stocker you would prolly never have a problem.

 

[toomany]

FWIW, I'm running rubber motor mounts and poly trans mounts (same kind the op needs). Been running the setup for a few years. Daily driving, towing, offroad, etc. Haven't had any problems with things cracking or getting all bent out of shape. This combo (350/465/205) has been swapped into 3 trucks, each time new (rubber) motor mounts are put in.

Not trying to start any arguments, just stating my experiance.

 

[kgblazerfive]

Probably been working fine cuz of the new rubber mounts, try a set of beat up old ones then the issues start happening.

 

[4xcrazy]

beat up old worn out motor motor mounts will cause problems anyways.

I recently had to change out the trans mount on the '94 pick up, was broke, bouncing around, banging, nasty. changed it, noticed the motor also sitting slightly angled, decided to swap out those mounts too, driver side was sitting on the frame, passenger side almost. Was a real chore on this thing with the 4.3 for some reason, but after all new mounts, wow what a difference in drivetrain vibrations seriously reduced, much better shifting and overall driveability.