Pinion Angle Question

[Pinkyman]

So i know this has been covered 157,654,759 times, but im looking for some insight. Ever since i put my rear 3.5" IRO leaf packs in, ive been getting vibrations at 20-40, and at 70 its pretty pronounced as well. I know its my driveline, and im pretty positive that it has to do with my pinion angle due to the lift and shackles.

I put new u-joints in the rear over the weekend, and checked the fronts (they are fine) and the vibrations seemed to have gotten worse. The vibes at 70 go away when i let off the gas, and from 20-40, they seem to be there no matter what.

Can anyone tell me if rear shims may help resolve this? Ive heard that they can, and ive also heard that they dont do anything unless you have an SYE...
I am not looking to buy an SYE at this point, and my t-case bolts are seized and i dont want to break them quite yet. I have not had a chance to check my angles yet, and i know you cant tell from a picture, but im posting one anyways lol.

http://i38.photobucket.com/albums/e124/Rocketryan1/20160207_131417_zpse7nevaw7.jpg (http://s38.photobucket.com/user/Rocketryan1/media/20160207_131417_zpse7nevaw7.jpg.html)

[4.3LXJ]

Well, no wonder you get vibes. I can tell by looking that the pinion is too high, or you may need to drop the tcase. Here is a link so you can figure it out

http://www.xjtalk.com/showthread.php?t=7299

[Pinkyman]

Well, no wonder you get vibes. I can tell by looking that the pinion is too high, or you may need to drop the tcase. Here is a link so you can figure it out

http://www.xjtalk.com/showthread.php?t=7299

Thank you for the link! Ive been reading up on it lots, and i understand how it is supposed to be.

I guess my question is if i might be able to get away with just installing some rear shims, instead of dropping the transfer case. The u-bolts will come off easily, the transfer case bolts, not so much lol

[Pinkyman]

Also, does the lower centering pin on the leafs allow for any movement at all? Like, could i loosen up my u-bolts, and move my pinion down a little, and tighten the u-bolts back up and maybe get my angle better by a degree or so?

[4.3LXJ]

Thank you for the link! Ive been reading up on it lots, and i understand how it is supposed to be.

I guess my question is if i might be able to get away with just installing some rear shims, instead of dropping the transfer case. The u-bolts will come off easily, the transfer case bolts, not so much lol

Yes, you can install shims. first figure out what you need from the link I gave you. Then install them and that should be it. And no there should be no movement possible even if a little loose if everything is as it should be

[Pinkyman]

Well I think I have found my issue. Time to oder up some 6 degree shims tomorrow....

http://i38.photobucket.com/albums/e124/Rocketryan1/2016-02-08%2019.47.27_zpsjzv8w93c.jpg (http://s38.photobucket.com/user/Rocketryan1/media/2016-02-08%2019.47.27_zpsjzv8w93c.jpg.html)

[4.3LXJ]

That will do it. Anything within 4° difference is good

[Pinkyman]

Well i just ordered my 6* shims..... Im kind of nervous, that seems like a lot for a 3.5" lift and 1" shackles. I guess we will see, i just dont want to have to do it twice lol

[4.3LXJ]

The reason for that is that normally you would need 4° shims. But your extended shackle changes that for every inch of shackle. So 2" more shackle makes you need another 2° on that shim