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I have a '68 C3 and recently installed a new RideTech rear coil over suspension. While replacing the suspension, I also change all U-Joint on driveshaft and half-shafts. When I took the car for its first drive, I had a bad vibration around 20 mph. I put the car back on the lift and can't seem to track down exactly where the binding is coming from. I unhooked the half shafts and still get the vibration, so I think have been able to isolate it to the driveshaft between the driveshaft and rear diff. I didn't have this problem before the suspension rebuild so I wouldn't think it's the posi cluckpacks. Because of a read diff leak, I did replace pinion and half-shaft seals. Retorqued the pinion nut to 65#. Added new gear oil (with posi additive) plus an addition small bottle of posi additive. Clearly I screwed something up, any thoughts?
Last edited by Travis Talbot; Apr 16, 2025 at 01:57 AM.
Do you know if there is a solid sleeve in the diff? It would not be original, but other than working with a solid sleeve, you don't torque the pinion but to a specific torque reading, like 65 ft/lb.
You have some expensive upgrades there. I would disconnect the driveshaft at the pinion and check the drag on the pinion. Also try indexing the driveshaft 180*
Binding at the rear diff...
