How do I?

Got vibrations. I need to measure my angles, (pinion, etc.) in the rear. I have an angle finder, but where do I take the readings from? Also once I have them, how do I figure out which size shim to get. I'm sure this is a simple thing, I just need a bump in the right direction.:huh:

Do you have a CV shaft or a Slip yoke?

As xj trail said what shaft do you have? I thought you installed a sye and double cardan. If you just have the stock shaft you might need to do the t case drop route. Others have more experience with that stuff

i have a stock shaft on a 99. I installed a 2" rancho add-a-leaf to correct sagging stock leafs and get vibes mostly during deceleration.

Ok the best way to measure it is to place the angle finder on the flat part of the yokes both at the slip yoke and the pinion yoke. There will be a place just flat enough to place the angle finder on. Jot down both angles, they should be with in 2 degrees of each other or think of it like this;

If you could draw an imaginary line straight out of both yokes at the angle they are at now the lines should not intersect or if they do it would be a long ways away from your Jeep.

Example;
Say if your pinion yoke is at a 6 degree angle pointing upward and your slip yoke is pointing 6 degrees downward all would be good or if they are with in plus or minus 2 degrees of each other it would be acceptable.

You will have to take the angles that you have and figure out which shim you need and which way to shim the axle.

Use good quality steel shims and new center pins.

I hope that helps, others may add thier opinions or expert advice.

Thankyou xjtrailrider. That is the info I was looking for. If it does end up that I'll need shims, any suggestions on where to get them. I'm thinking I'll need some new u-bolts as well. I re-used the stock ones and with the AAL they are just about out of thread. I would think that the added space of the shims I'd be pushing it.

If you have a double-cardan driveshaft then your rear axle pinion should be pointing at 2 degrees below your transfer case output shaft, reguardless of angles. If not you need to measure the angles and adjust with axle shims.

The diagram below shows the correct configuration, if you have a double-cardan constant velocity driveshaft.

Ok, so after reading the OP reply, I noticed he said he has a stock driveshaft in that case, the rear axle pinion should be parallel to the transfer case output shaft. This diagram shows the correct configuration if you have stock driveshaft:

nice diagram.....


Step 1.
put the angle finder in the middle of the ds.Note the number.This is the horizontal slope of the ds.

step 2.
take the angle finder and place it on the round part on the axle tubes near the diff cover.Subtract whatever number you get from 90.This is your pinion angle

step 3.
subtract the pinion angle number from the horizontal slope number of the driveshaft.This is your driveline angle.