JustExpectEveryProblem

Hello all,
One of many new members on the forum. Long time user, first time posting anything. So here it is, Soon I am going to be undertaking my second XJ project and be installing my second lift. Although, I am not an expert I have an okay understanding of how everything under the jeep works.
A little background on the jeep. Its an 01 Sport with an NP 231 t-case and a c8.25 rear axle. No worries about the low pinion front axle because I have a spare high pinion I will be swapping in for now. I am going to be running a 5.5 inch Rubicon Express long arm lift.
My questions to you. I know I'm going to be needing an SYE and CV rear driveshaft. Im not exactly sure what length shaft to get and brand. Secondly, I read something on the rubicon express website about shimming to change the pinion angle. What shims do I need to achieve my desired pinion angle after the 5.5 inch lift and no T-case drop? Anyone have any personal experience? If so feel free to share the size shims you used. I may have some follow up questions for your comments.

Thanks Everyone.

TRCM

You really should wait until the lift & SYE are installed, and then take measurements to see what length D/S is needed, and what angle shims are needed FOR YOUR JEEP.

Saves a lot of guess work and having to redo things if you guessed wrong.

I say for your jeep, cuz extra weight like bumpers & such can affect the shims needed.

WyoCherokee

I was able to get away with 4 degree shims at that angle and No SYE. But as mentioned above, wait until you get the lift installed and get the SYE installed. You can then measure for your driveshaft. many of the manufacturers show you how to measure when you get to the ordering process. When ordering something spec built like that, it is best to actually CALL the sales number so you can make sure you give them the correct measurement. Tom Woods or Adams are probably the 2 most popular.

Stroked98Xj

I will second this, with the additional recommendation that you do not buy ANY shims, but instead install the lift, install the SYE, and leave the rear perches unwelded until after the lift is complete. Put the weight of the Jeep fully on its suspension, and then measure for a CV rear shaft. Keep the rear perches unwelded until after your new shaft is installed, and then you can put a jack under the rear pinion and slowly rotate it up to match the drive shaft angle coming down.

Best practices suggest to line up the pinion yoke with the angle of the drive shaft, but that's at constant load. For a 4.0L, I point the pinion down 1.5-2 degrees. For a stroker or any V8 with higher torque, I point the pinion down 2-3 degrees lower than the drive shaft angle. This is because your pinion will rotate up a degree or 2 under power, and generally a U-joint manufacturer will specify they need at least 0.5-1 degree to properly move the needle bearings inside the caps. Let's face it, our Jeeps have axle wrap unless you 4-link it or build an anti-wrap bar, so getting the drive shaft and pinion angle is quite important in our short wheelbase lifted SUV's.

Bottom line, don't weld the rear perches until the very end, and have a custom CV shaft made to your specs. You can buy any XJ front shaft and have it rebuilt if you want to save a little bit of $$$ on the CV head - which is usually the most expensive part aside from labor.

TRCM

Rear perches....no mention of cutting and installing any new perches.......

But I agree, if you are putting on new spring perches on the rear axle, you just set them to your pinon angle and weld, no shims needed.

Stroked98Xj

Sorry, old habit. I forgot not everyone replaces XJ leaf perches. The OEM perches are so short and weak that every single XJ I've owned (5 now) all have suffered from bent over perches which induces clunkiness under the spring. If you're lifting the rear and have the ability to weld 1/4", now is a great time to add a stronger leaf perch with a wider base- also help lessen axle wrap.


https://www.ballisticfabrication.com...f-spring-perch

TRCM

I don't disagree..........but thought I had missed something.

JustExpectEveryProblem

Thanks for the feedback everyone. I will be waiting until the lift and SYE is on before ordering the shaft. There was mention of welding on new perches. In regards to that, I am not the best welder. Would it be worth it to go to a local shop and get better perches welded on at the right angle? Or just add some shims? Probably going to be doing some moderate weekend wheeling in the PA mountains. Keep in mind its only a c8.25 so I may swap later down the line.

TRCM

Just look at your spring perches once you have the leaf springs off.....may not be a bad idea.

If they aren't flat across the pad area front to rear, may be needed.

JustExpectEveryProblem

Sounds good I will assess the situation when I get there.