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Yes, neutral balance damper , no weights on convertor except a thin flat 8G weight on the back side. Never had a problem like this, and the machine shop says the notched flex has to be used. I thought that flex was for cast crank engines. Thanks for the replies. Yes , shakes in any gear.



Sounds like they balanced the engine wit hthe flexplate so I'm not surprised that it shook worse when you swapped on the real neutral balance one.

What's odd is why the neutral balance on the front and weighted on the rear ? The engine is NOT neutral now and any parts swap is going to be an issue.

I'd start by looking at the balancer on the front and the pulley that is on it.

Someone else said something about forged vs. Cast material, that doesn't matter if the rotating assembly was balanced as an assembly , which it sounds like it was .

Time to pull that motor.