Driveline alignment: 2wd to 4X4

Box stock '98 XJ 2wd. 4.0L Installed '98 AW4 with np231. Lifted Jeep 2" with pucks in front, stiffer leaf aft. Wedges between leaf springs and axle pads supposedly good for 2" lift. (correctly mounted with thick part toward the back of the jeep.)

Angle between engine and drive shaft is 10.6º drive shaft to differential is 7.7º Drive line operating angle is 2.9º, but each U-joint is well beyond the recommended 3º and of course, the drive train rumble from about 25mph through 40 mph is awesome. (angles carefully measured with Tremec's app)

I guess my question is WTF? Is it possible that the 2wd 8.25 diff has the spring mounts at a different angle than the equiv 4wd -- given the much shorter driveshaft in the 4x4?

The remedy, short of an SLE, seems to be lowering the transfer case as if the jeep had a 6" lift. Once again, WTF? Comments? Observations? Slander?

Each XJ is like a planet, not all have the same composition. 2000-01 brand new off the Dealership lot sometimes needed a t-case drop to solve the original owners complaints of drive line vibes.

Do your lift kit leaf springs have the wrong shims ?

Motor mounts, transmission mount, and u-joints are fresh ?

Tim_MN said:

Each XJ is like a planet, not all have the same composition. 2000-01 brand new off the Dealership lot sometimes needed a t-case drop to solve the original owners complaints of drive line vibes.

Do your lift kit leaf springs have the wrong shims ?

Motor mounts, transmission mount, and u-joints are fresh ?

Click to expand...

What was changed in the 00-01 model year that would’ve caused those complaints? All that comes to my mind is the LP d30.

As for the OP’s question, there is no difference in a Chrysler 8.25 from a 2wd versus one from a 4x4. 2wd and 4x4 models share a lot of the same parts including the front knuckles on the 2wd monobeam axle being interchangeable with those of the d30 as they also share all the same brake parts.


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"Each XJ is like a planet, not all have the same composition. "

Even with my limited experience, I'm happy to join in that observation.

Looks like there's at the very least a TC case lowering in my future as well as higher angle shims between axle and springs, if not both.

New U joints on both ends of drive shaft, new engine and transmission mounts too.

Thanks!

You may be pulling the slip yoke out too far from the transfer case. Which means your yoke is riding more so on the end of the output shaft. That will cause a vibration. Typically you want the yoke 1" out from the output seal so there is a relatively even amount of slip in and out. But I am used to dealing with sports/performance cars and their driveline requirements in my line of work. I would imagine the 231 isn't much different though.

I bit bullet on an SYE and never looked back. However, I did for a time run a Hack N Tap and it worked rather well for what it was. Fixed my vibration issue form being lifted.

kcox506 said:

You may be pulling the slip yoke out too far from the transfer case. Which means your yoke is riding more so on the end of the output shaft. That will cause a vibration. Typically you want the yoke 1" out from the output seal so there is a relatively even amount of slip in and out. But I am used to dealing with sports/performance cars and their driveline requirements in my line of work. I would imagine the 231 isn't much different though.

I bit bullet on an SYE and never looked back. However, I did for a time run a Hack N Tap and it worked rather well for what it was. Fixed my vibration issue form being lifted.

Click to expand...

You speak wisely. I'm always looking for a way to save money. And that 's the source of some of my largest expenditures. The SLE (and double cardan) is clearly the fix for me.