centuryhouse

I'm finally going to put a 3" lift on my 2000 XJ this week. After all the reading I'm confused about one thing.

Are shims usually needed on a 3" lift if you are getting a SYE?


In addition to the lift components, I am installing a brand new Adams Driveshaft Custom made 1310 Rock Crawler CV Driveshaft and a Rough Trail Sye Kit.

Thanks!



2000 Cherokee Sport, Chrysler 8.25, 321 transfer, new SYE and rear driveshaft.

bad_idea

I just did a SYE in my 90 w/ an 8.8 install at the same time. That is the extent of my experience I am speaking from, nothing more, nothing less.

The instructions that came with my PORC SYE stated the pinion should be 2 degrees down (when the axle wraps under acceleration, it will be at 0). So yes, you will need to shim. You will need to guess and test a bit to find the right angle. It's a PITA.

Give you an example. The driveshaft is at 10 degrees, the pinion is at 5 degrees. A 3 degree shim should get you to 8 (a difference of 2). WRONG. When you tip the axle, the driveshaft angle changes too. You'll probably only put in a 2 degree shim at that point and the pinion will be at 7 and the driveshaft at 9. These numbers are all pulled straight from my *** for the purposes of illustration.

I did the SYE and 8.8 at the same time to alleviate the headache of shimming. I was able to put the 8.8 in w/ the spring perches loose and rotate the axle until the pinion angle was right. Then I tacked the perches on and welded it out.

If you don't want to install a new axle at the same time, I would suggest the following. Measure your initial pinion angle and driveshaft angle after the SYE is installed. Loosen u bolts on axle, jam a screwdriver in between the spring perch and spring to act as a shim. Keep jamming deeper until your angles are right. Subtract the new degree from the old, there is your required angle. Theoretically.

ROGR333

Every rig is different. My 92 has a 3" that was on it when I bought it. The *** sagged like they all do so I added rear shackles and got her level but immediately noticed bind in the u-joint at the xfer case. Did an sye and debated on shimming the rear but didnt... 0 prob. Buddy with same set up on his 92 needed them to eliminate vibration. Bottom line you wont know how much shim you'll need until she is lifted and rolling anyway.
Side note, my 97 with a 4" lift and 1" trans spacer didn't need an sye or shims... Go figure.

centuryhouse

Interesting. Thanks for the info guys. Funny thing, for the last 4 years I've thought about lifting and didn't because the SYE was cost prohibitive, but I'd hard you could get vibrations if you didn't. So I finally sprung to get the SYE so I wouldn't have to deal with that, and got a lift - and then realized the SYE doesn't eliminate those problems, it actually causes some of them :-/