12 Bolt in a Nova help...

[bs46488]

I just got my 1970 Nova LS swap project on the road. I have about 200 shake down miles on the car.

The previous owner put the 12 Bolt with 4 leaf Z28 springs into the Nova and had new 3.42 gears installed in 2011. It has been a project since that time and has been sitting/moving back and forth in my garage.

I replaced the outer axle seals because of a leak and put in fresh conventional 80w90 gear oil and a bottle of additive. About a 100 miles ago I added a 2nd bottle of GM additive.

The rear end has a horrible jerking/clunking noise. The noise is extremely loud and you can feel it in the car at low parking lot speeds. Going straight down the road no issue, but as soon as you hit the gradual turn on the exit ramp it hits hard and feels like the axle will continue to go straight. When driving around a corner the axle feels like it shifts positions. My dad watched me drive the car at low speed circles and he can see the outer axle/wheel hub physically jerk front to back.



I can't find any loose suspension parts. Everything is torqued to spec. No noticeable wear items in the rear.

Any suggestions on what to try next?