shimming a rearend

I have a 89 yj I sprung over,instllaled a cv rear drive shaft ,new tires frnt end alinement,slip yoke elemanator,getting a vibration @ 25mph,someone suggested I shim the rear end so it angles up to the transfer case,HOW do I do this.5-6"lift,how do I measure to know what exactly is my lift

I have a 89 yj I sprung over,instllaled a cv rear drive shaft ,new tires frnt end alinement,slip yoke elemanator,getting a vibration @ 25mph,someone suggested I shim the rear end so it angles up to the transfer case,HOW do I do this.5-6"lift,how do I measure to know what exactly is my lift

When using a CV driveshaft, your pinion should point straight up your driveshaft so that your rear u joint operates at 0 angle. Ideally, when you had your spring mounts welded back on the axle after the spring over, they shouldve been welded on at the correct angle. You can use shims to correct this though. I cant tell you exactly what degree to use, that depends on how much lift you have, and how long your driveshaft is. When setting your angle up, keep in mind that while you drive down the road under power, the torque to the rearend is causing the pinion to raise a couple degrees more than it is just sitting still. This is assuming you dont have a torque bar. I just posted something about this on the XJ board. you need to go to a hardware store and get an angle finder. This will get you pretty close to the correct degrees.