Brian71583

Soon my 8.25 I built will be going into my XJ. It should have been in 2 weeks ago but cracked leaf springs and broken degree shims delayed progress.

Due to different issues I have had with my Jeep I am not taking for granted that anything was done correctly by the PO in installing the lift.

Its a stock engine/tranny/TC with a 4.5" lift.

The TC has a 1.25 drop on it.

The original D35 had degree shims that cracked in half upon removal.

How can I figure out what angle shims I need to install my 8.25? Do you normally need a TC and degree shims both? I don't want to have to get the new leaf springs and install them and the rear and measure then order the shims and have more down time. I'd like to install everything correctly at the same time if I can.

Lead Foot

To set up a stock rear driveline (single u joint at each end) properly the angle of the t case output needs to match the angle of the pinion. (parellel, not necessarally pointing right at each other) Most people will actually leave the pinion pointed a little further down to compensate for the little axle wrap that allows your pinion angle to change and rotate upward under torque. Looking at these angles first will help you find out if you need to shim the rear spring perches. If you find your driveline isnt long enough and it pulls out of the transmission when at full droop then you need an SYE or you might be able to get away with a t case drop.

To properly set up a front stock driveline (single joint on one end, double cardon joint on the other) in the front, or the rear with an SYE.... Then your goal is to have the pinion angle perfectly strait with the driveline angle itself. Esssention the pinion will point directly at the center of the double cardon joint on the driveshaft that is bolted to the fixed yoke equipped on the front or back (SYE) of your transfercase.

I hope this helps.
Kris Froehlich

Brian71583

Ok...so.. If I am reading your response right and I measured correctly I don't need any shims. Is that out of the realm of possibility with a 4.5" lift and 1.25" TC drop, or did I measure something wrong.

Right now my Jeep is on jack stands because there is no rear in it. My TC output is level so I found the angle of the TC cross member. That is 5 degrees. So that puts my TC output at a 5 degree angle down.

The new rear is sitting on saw horses so I chocked the rear so that the spring perches were level and measured the angle of the rear at the top of the pinion and that is also 5 degrees. so I would assume that when mounted on the leaf springs the pinion should be angled up 5 degrees???? Would I be right with that assumption or aren't the spring perches a level spot.

Both matched 5 degrees so I would think I don't need any shims?

Lead Foot

You are on the right track but that is ALOT of assuming. Your pinion angle on your axle will change depending on specific spring arch and length of shackles. I doubt the perches are ever level. It is for sure possible that you dont need shims though. Sadly, you need to bolt everything together, get the rig sitting on its own wait, then torque everything down. From there you can start measuring angles and decide if you need to add some shims in there or even remove the t case drop.

I can also almost garauntee you that your t case output is not level to the crossmember with that 1.25" drop being on there. Probably the best way to measure this is put the driveline in the case with the slip pulled out just enough to get your angle finder and level in there or even better a digital angle finder. If you have a smart phone with the gravity meter thing and a flat edge on the case like an iPhone you can also download an app for this.

Then do your refiguring. like I said, I think you get the concept. Just got to get everything together first and measure from better locations.

SeriousOffroad

Ditch the T/C drop.
Install an SYE.
http://www.seriousoffroadproducts.co...it-87-06-XJ-TJ

Remove the OEM spring perches and set a pair of Anti-wrap Perches on the tubes.
http://www.seriousoffroadproducts.co...x-Spring-Perch

Lower the heep back onto the axle (with the tires in place) and use a floor jack to raise the pinion so it points directly at the t-case output. Tack weld the perches and then remove the axle to weld the perches on.

Reinstall the axle

Done

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Lead Foot

Yes, this is the most correct way to do it. Shims can be a pain to work with and dont last to as much abuse.

Im sure that a SYE is already on your list, at least I hope it is. I wouldn't go through the hassle of cutting off the stock mounts, buying new ones, and welding them on though until you have assembled your current set up and know for sure you need to adjust the pinion angle. That would be a waste of time and money in my opinion. If it ain't broken, don't fix it.