Spring pack/shim question

I've already searched for those looking to flame, and have not found much to help. So......

I have a RC 4.5 with AAL, and Tcase drop, I just picked up some 3.5 RE full packs from a guy on here and he said they had 2 degree shims. I plan on using the leaf packs with MJ shackles which are about 1" longer than stock in order to achieve the 4.5 in the rear.

With that being said my question is are these shims correct for this set up, and should I loose the drop or shims, or keep one or the other, or both? Thanks in advance!

suspensions are funny things, no one can definitely say what will or will not work. try it and see, it's a simple job to change it out again if they don't work...

and for search, try google, they know their way around better than 's search engine

I agree with avnsteve I may or may not need them, it might help, it might make things worse. I would try and install them with the springs and see how it drives I would bet that it might help. If not there way easy to install and take out.

It all depends. I'm at 6 inches with a 1 inch drop crossmember and no shims. I'm running 2 inch extended shackes and 3.5 inch RE leafs and no shims. The diff is tilted enough to afford me a vibe free ride without a SYE. My 95 XJ has 3 inch aal rear and no TC drop, no SYE and it vibrates like the shaft's coming appart. What I'm trying to say is no two are alike. You should put it up the way it is and measure your angles. Try to get the two u joints turning on the same plane (or in phase) to eliminate vibration.

mflueras said:

It all depends. I'm at 6 inches with a 1 inch drop crossmember and no shims. I'm running 2 inch extended shackes and 3.5 inch RE leafs and no shims. The diff is tilted enough to afford me a vibe free ride without a SYE. My 95 XJ has 3 inch aal rear and no TC drop, no SYE and it vibrates like the shaft's coming appart. What I'm trying to say is no two are alike. You should put it up the way it is and measure your angles. Try to get the two u joints turning on the same plane (or in phase) to eliminate vibration.

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Shackles can also help you pinion angle too, some do shackles to correct a pinion angle and gain some lift. I am going to run some 2" shackles just for that reason.

thanks everyone, I guess i will just throw it on with the shims, see how it goes and take it from there.

I have a 2001 XJ, the same 3.5" RE rear springs (After a year of break-in they still give 4.25" lift fully loaded)
& a Slip yoke eliminator (No Extended shackles & No TC drop).
It took 6 degree shims to eliminate the driveline vibes.