vibration

Jeepers............ Sounds like a gremlin..............

The only vibrations I've had issues with have been with internally balanced motors using an externally balanced harmonic, or torque converter.......and vice versa.

I've had the issue with 3 cars, and it was usually solved when we determined if the motor was balanced internally or externally, then examining carefully the converter and balancer to be sure if they did or did not have counterweights.

Internally balanced motors (IS yours balanced?) cannot use an externally balanced harmonic.......they will have weights bolted to the back side usually and result in vibration such as you speak of.....but converters also are neutral or balanced externally, and can add to the vibration.

We've solved 2 cars now with vibration by removing external weights on harmonics and converters.

You probably know this already, but it's all I can add to the mix from our experience. You need the right combination to have no vibration. 8)