Pinion angle question

Ok so after I installed my stiffeners and crossmember my pinion angle changed. I had 6 degree shims in but they were to great. I put 2.5 degree ones in and I still vibed so I put some 4 degree ones in and still. My driveshaft is reading 16 degrees and my axle is reading 17 degrees. And thats with the 4 degree shims in there right now. So If im reading this right I would need a 1 degree shim correct??

I'm glad your asking this.... I've been wondering how this works as well

Haven't been following your build, so I have to ask: What kind of drive shaft are you using?
If you have a stock style drive shaft(single U-joint at each end) The pinion shaft should be approximately parallel to the transmission output shaft.

If you have a CV(double cardan)joint at the trans output/single u-joint at the pinion, the pinion should be approximately parallel to the drive shaft. Most people build in 1/2- to 1 degree "pinion down" angle, on the theory that the axle is going to be rotating up slightly under torque loading.

If you want to go a little more in-depth try Tom Woods web site:
http://www.4xshaft.com/
Follow the "tech info" link at the top.
Start with "Geometry 101", then "vibrations" and "slopes vs angles".

Hope that helps. Good luck!

As in your other thread,it sounds like 3* shims would be correct.What driveshaft are you running?Has it been checked out and properly balanced?