67 Rear axle bounce

[Hart_Rod]

Originally Posted by oldman3

OK guys, I'm bringing up this old thread to update on the rear axle bounce.

A short story first, this thread is about 18 months old, Jimbo's wife had their baby, and has since had another, so his time as been limited to doing anything with the truck. We also had to change the engine (posted in his build thread today, last 2 pages). While we did that we also change part of the drive shaft alignment. I talked with several different drive shaft makers and they all said that it was possible that the 2 piece drive shaft could set up a wobble to cause the bounce. What we did was knock out the rivets from the carrier bearing bracket, and turn it upside down. Took a string from trans to rear axle pinion to make a straight line. Moved the bracket up till drive shaft was it line. Marked and drilled 4 holes, installed grade 8 bolts and tightened down. After breaking in the new engine, we when out on the four lane and man what a difference. We pulled a couple hard throttle pulls to 5,000 rpm in drive (3rd gear) and was smooth. Got up to 90 mph and still smooth. We still have a little vibration, so he is going to take the wheels and tires to a new shop in town that has a laser balance machine and works alot with large wheels. Here's a few before and after shots of the change..Jim

Glad you figured this out Jim. Come to find out my vibration was caused by a new set of Moser axles that were machined incorrectly...... go figure.... Oh well, at least I have it figured out now. Hopefully they will do the right thing and replace the axles free of cost.