Thanks Tugly, I will be looking at the electrical end of things when I have time. For now, the vibration has been tracked down to the torque converter for sure. The new TC and flex plate wobble around just as bad as the old ones did. I'm thinking bad trans pump bushing and/or converter not properly centered in the crankshaft adapter ring.

Chris

 

Thought I would close out this old thread. It took over a month but the problem was staring at me all along. The culprit was an off balance torque converter.

Here are photos of the TC hub that pilots it to the crankshaft adapter:





The forward end of the hub where it goes into the crankshaft spacer ring is unevenly worn. It is shiny on one side but dark on the other, indicating that the converter wasn't properly centered.

The problem was compounded by the fact that when I installed a new torque converter I made the same mistake . In a hurry to get the truck back together, I didn't make sure the converter was centered, and it wobbled just like the old one. Since the symptoms were the same with a new part I started looking elsewhere and wasted more time.

Moral of the story: take your time installing flexplates and torque converters. Make sure the input shaft, stator and pump are all properly engaged as the converter is slid into the transmission. Draw up the bellhousing slowly, keeping it parallel to the engine adapter and free of anything that might prevent proper alignment. Verify that the converter hub is centered on the crankshaft before the nuts are torqued down. It only slides into the ring about 3/16 inch so it's easy to miss.

Hopefully someone else might benefit from my mistakes and not have to pull a transmission 3 times in one month .

 

Lots of good info here. Thanks for sharing

 

Well I've got a similar vibration, and was hoping your balancer would solve it. Glad you found it. TC/flex plate has crossed my mind as well.