70 Challenger - vibration problem

My buddy bought a 70 Challenger a couple of years ago and just completed the restoration. The car shakes and vibrates pretty badly at about 55 mph. He had new u-joints put on and had the driveshaft balanced. Now he can drive a little faster but it still shakes badly at around 65mph.

The automatic tranny was rebuilt, 440 six pack motor rebuilt and balanced. New wheels and tires balanced, front end aligned. It has an 8 3/4 rear.

Any ideas as to what could be causing this?

Thanks, Rob

There is a factory Technical Service Bulletin on "Vibration diagnosis procedure", it is 20 pages long, very thorough.

Go to this link;

http://www.hamtramck-historical.com/1974-Dodge-TSB-Index.shtml

Then drop down to Chapter 25, it is the fourth one down in this chapter. Click on each page number to read that page.

Barry

I had a similar thing happen to one of my cars, it would shake the doors off. It would vibrate badly even in the driveway. I had replaced the torque converter when I rebuilt the engine and transmission. It turned out to be a bad torque converter.