i did a shackle flip a little while back and 2 weeks later i was getting vibes in 3rd gear (30 mph) under power i figured it was due to the pinion angle change. the angle is actually concave down when before it was concave up a bit. I welded in some angled shims and found one of the u joint bolts was a little loose. I tightened it up and now with the shims the pinion angle is about strait. I noticed a bunch of play in the u joint connecting to the pinion. like 1/4 of an inch. Now i get vibes at like 45 mph. They aren't extreme just annoying. I think I need to get bigger wedges to move the pinion down more to be at stock angle. This angle is not strait correct? ALso I was going to buy a new u joint.

 

If you have a single u joint at each end of the shaft, then the angles should be equal and opposite, preferably not much greater than 3 degrees. If you have a CV joint at the transfer case then the pinion angle should be near 0 degrees .
Mark

 

hmmm. ok that helps. I htink i need a bigger shim then. Ill try measuring some angles. I dont have a cv joint. i have a reg cab long bed f150.