67 Rear axle bounce

[oldman3]

Ok guys I'm going to try this again. This time I'm asking the question in the correct forum.

I posted a question in the 67-72 message board in May 2011, about this problem. That thread number is 463544 if anyone wants to read it. I got back several answers and tried a couple things, but still have the same problem. So her goes.

I redid a friends 67 pickup a couple years ago. We installed a drop kit from CPP. Kit #6370BDK 3" front/5" rear. We did a 5" coil spring drop #RCS603-5 in the rear with relocators for shocks, new shocks, c noth, etc. The pickup is a 67 longbed stepside. It was orginally a 1/2 ton heavy duty long bed. We kept the longbed and added a gas tank at the rear of the frame. What is happening now is when you run down the road at about 70 mph, the rear axle bounces like a rubber ball. It's not real bad, but you can see it if you watch from another vehicle. Since that original post I've removed the 5" coil spring (thinking it couldn't handle the weight) and installed 4" drop heavy duty coil springs #RCS603-HD from CPP. Changed the angle of the shocks, changed tires front to rear (same size) and it has made NO difference.

I've got about 25 pics of the old setup and changes made. I've got pinion angle, trans angle, two piece drive shaft angle, trac bar angle, shock angles, etc. When I first posted this problem I was not aware of the Suspension forum, I now check and read it daily. I have a couple items I think maybe the problem, but I want to check here and see what others think.

I'll stop running off at the mouth and post some pics with info....Jim