I have a vibration problem to solve. This issue goes way back to the 80's when I last had the car on the road. From what I can recall, the vibration was more of a problem when I had 410 gears in the rear because of the higher rpm at driving speeds. I tried putting a vibration dampener on the tailshaft of the transmission which didn't seem to do much. I went back to 323 gears which made the situation more tolerable. The motor is a 340 T/A which was balanced when I had it built. I recently did a complete restoration of the car and had the motor again rebuilt. I added a Summit dampener, Gear Vendors Overdrive, new balanced driveshaft, and 410 gears again. The only thing that went back in original was the torque converter, which is a TCI. I still have a vibration that I think is even worse than before. Could this be the torque converter? It seems to be the worst at a certain rpm range and under moderate acceleration, like going up a hill where you can maintain rpm. It will diminish if I shift into overdrive. I know my pinion angles are good. What is the best method to troubleshoot this? I wanted to isolate the engine from the transmission, but it's not possible to unhook the torque converter and start the motor like a chevy. Thinking of pulling the tranni and having the converter tested, but want to get some thoughts from people with experience first.
