I have vibration in the drive line that is occurring when I take off up until 20 mph. I've started with 1 (1/4") shim and gone up to 9 shims installed. At 8 shims the drive shafts are pretty even with one another. That's where I have it set now with the least vibration, but can't completely get rid of it. Anyone have any other senerios? Maybe different size shims?

I have 6" of lift in the rear. Rule of thumb is generally (1) 1/4" shim for every 1" of lift. That should put me at 6 shims, but it's not working.

 

Have you made sure that the slip splines in your driveshaft are lubed up enough? If they are not lubed then it can't slip enough and causes vibration like this.

 

The trucks only 7 months old with 4300 miles so everything should be lubed, but I'll check it out.

Another thing is the OUO blocks have 3 different pin holes to align the differential. I used the middle hole. Is it possible the rear end is to far up or to far back?

 

How's the pinion angle? U- bolts tight?

 

I have tapered blocks so the pinion angle is pretty good. I'm going to mess with it this weekend and get some pics of all the angles.

 

Did the problem start immediately after lifting it?

 

Yes. It did it the first time I took off after the lift was on.