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No vibes before lift. 3.5 in. Lift that got me 21" from center of the wheel to bottom of oem flare on the front and 22" on the rear. Rude measurements of TC tail is about 2.5 degrees down, driveshaft 19 degrees down, and rear pinion about 5 degrees down
Do you have a tcase drop in? Simply installing leaf spring shims isn't going to fix your vibes. You have a hard angle going into the tcase which you need to lessen by either dropping it down or installing an SYE.
No, don't have a SYE and I see what you mean. Looks like the angle from the TC is worse than the diff. I was hopeful to get by with shims. Guess I will do the SYE and maybe a front shaft will work. An emoggie of tossing money out the window is needed right here.
You could likely get by with a TC drop. You can make your own with some square tube and a couple longer bolts. TC drops are typically frowned upon, but they do work. My father has had one in his YJ for years. No issues.
I'm not saying you shouldn't shim the rear because it certainly looks like it needs some but that's not where your problem is completely. Without taking some of the severity out of the angle at the Tcase, you're still going to have vibes regardless of shimming the rear diff. And TBH, a good rule of thumb is to just factor in an SYE even with a 3.5" lift lol. Sucks but they usually make life better.
With the SYE you should shim the rear axle so it is 2 degrees below pointing at the transfer case. Meaning the angle between the diff and the driveshaft will be 2 degrees different. Here is more info than you need: http://www.4xshaft.com/driveline101.html
Assuming you are doing the full kit, I suggest you pull the TC from the Jeep. Adds about 1.5 hours to the job (bolts are a PITA to get to), but makes the job easier. Much easier to work on the bench than under the Jeep. I was able to use the front shaft out of a 4 door, AW4, 4.0l. I am running an 8.8 though. As far as setting pinion angle, I did that when I welded the spring perches on the axle.
It doesn't matter what angle is more severe actually. You can shim the the difference to parallel the tcase. I do it on all the jeeps I lift and works great. Usually use 4-6° shims depending on lift. Shims typically won't work for over 5" of lift as the angle is to great requiring a SYE.
Look up how driveshaft angle work for that style of driveshaft.
Don't waste you time with a tcase drop.
And yes a SYE is the best route but not the only one.
Last edited by MoparNJeep; 12-20-2016 at 08:35 AM.
12-18-2016, 01:49 PM
Need help on shims for rear diff.
