It happens in all gears plus park and neutral. I have replaced the engine, motor mounts, transmission, converter, flexplate. i had a 350 in it before and now a 400 and i do have the right balancer and flexplate on it. i need help on maybe what else it could be. i looked to see if it was touching anywhere on my car but i didn't see any. could maybe the motor mount be bad because they were new when i put the 350 in before the 400 and it did it with both engines? bad harmonic balancer? anything helping would be great Thanks

 

I have the same problem. I just started a new thread on it too. Let's see what the pros have to say.

 

what mounts did you use, poly urethane mounts will cause a bunch of vibration.

 

Were these brand new balancer and flexplate? Maybe one of the weights came off.

 

Maybe bad u-joints or driveshaft? You said the tranny was replaced, did you replace u-joints?

 

I think we can rule the drive shaft and u joints out because he said it still does it in neutral and park.

 

LOL guess that didn't soak in.

 

the flexplate was new with the tranny. the balancer has been the same. i just tried the torque converter turning to the next bolt and i think i found a good balance point. hopefully this is it. thanks

 

Update?

 

I would check harmonic balancer.