67 Dart 270...Project Old School

One of the things that bugs me on the Dart is the wonderful pulsating vibration that seems to start around 60 MPH. Getting in and out of the throttle changes the pulses. The 8 3/4 is rebuilt with new axles and bearings. The driveshaft is new from Victory drivelines. When I had the front end aligned I also had them rebalance the rear tires. The tires were out of balance, but it didn't make any difference in the vibration I am feeling.

The vibration really feels like it is coming from the rear end. After doing a search, I found out about u-joint working angles. I pulled out my angle finder and quickly realized I never set the pinion angle on the rear.

First up I measured the rake of the car which I got 1 degree negative. Measuring the engine I got 2 degrees down. The drive shaft measured 2 degrees down and the rear was pointing 1 degrees up. Hummm...that doesn't look right.

Saturday morning I hit all the parts stores in the area and managed to come up with four, 2 degree wedges. I was going to have to stack two wedges on each side in hopes of getting 4 degrees of change. I loosened the U bolts on the rear and slid in two wedges on each side and tightened everything back to spec.

When I re-measured I got -3 degrees on the rear and 3 degrees down on the driveshaft. Road testing showed the vibration was still there, but now it didn't start until 61/62 MPH. However, at 50-55 MPH the car felt much smoother.

I am thinking I need to come up with either a 6 degree or a 7 degree wedge to get the nose of the rear down a bit more. What has been your experience?