Tranny still shifts fine, but I noticed a knocking/clattering noise about a week ago. I thought it was just something loose from the recent new motor install. The noise intensified as the days went by so I unbolted the converter and checked out the flywheel, everything looked fine there. Started it with the converter unbolted and everything was ok. Connected the convertor back to the flywheel and it still sounds like someone is under my car banging around with a hammer. I got under it while running and its definitely coming from the converter area. I've had a cracked flywheel before and this sounds nothing like it.

Since the ACT Performance transmission/ local speed shop built converter/balanced driveshaft install i've had a vibration coming from under the car it gets worse the faster you go until the car feels like its gonna fly apart. Its kind of a pulsating vibration. It would even vibrate in park if you revved it up. I had the converter sent back in after the previous install and they rebalanced it "said everything was fine but I noticed the weights were in different positions than before". It seemed to vibrate less than before and I rotated the converter to different positions until it I got the least amount of vibration. With the old motor it would still vibrate at high rpms and then the constant vibration from 53-54mph on up, just where I have the converter set to lock in. The new motor was spun balanced and it didn't seem to vibrate at all while at high rpms, but I still have the 53-54mph on up vibration. I think the old motor was getting the main bearings wore out from the vibration since it got worse the more miles I would put on it. Either I have a badly balanced converter and driveshaft or a bent input shaft and output shaft, or the vibration just resonates with the car while the driveshaft is at a certain rpm hence the vibration from 53mph and up.

I'm pulling out my hair on this vibration thing, but since I have to remove the tranny anyways because of a bad converter, or the tranny caused the converter to go out. I still have my stock 4L60E but it doesnt have the beefier parts in it to handle 400rwhp. I may have to take both of them to a shop and have them "frankenstein" both of them together with a fresh rebuild and a new converter.

Oh yea, the ACT Performance tranny shifts firm from 1st to 2nd but it shifts like a caddilac from 2nd to 3rd with a slight pause between shifts "feels kinda like riding in a luxury car", I have the tranny pressure max constant set at 115psi and the pressure tables set at 115psi@wot shifts. I think they forgot some parts when they built mine.

Sorry to ramble on but any tips or suggestions would be great.