Does anyone know if there's angled shims in the rear end on 4wd trucks? I added 2 inch blocks to my rwd, but for the life of me, I cannot remember if I added the shims when i had lowering shackles. Maybe the truck came with them.

I ask because I have a low speed 20-30 mph vibration and thinking the shims are causing it.
Thanks

 

I don't know but the angle the driveshaft makes with the pinion has to be the same as the angle it makes with the transmission shaft to keep the driveshaft from vibrating.

 

Thanks, that brings up a new point. I've got Rancho Quick-lifts, so the front is also 2 inches higher, not sure how that figures into this.

 

The front end height will not affect the angle of the driveshaft to companion flange at the rear axle.

As to the rear and any angle shims, I took 2" high OEM blocks out my '07's rear when I lowered it, I used new shorter U-bolts too. I think there was some slight taper to them, but there were no "shims".

 

I ended up putting in a 1/2 inch spacer bar in the carrier bearing which improved things significantly. Tomorrow I'll add another 1/8 inch to try and Permanently fix this.