NP 242 blues

T

tfluthy

NAXJA Forum User
My son managed to blow up his 231j transfer case because of reasons. Anyway I want to put on a 242j transfer case.

2000 xj
4.0
automatic transmission
Sport trim
No lift

I have the linkage off of a 242 jeep, bezel, shift gate.

Reman 242 from midwest transmission

The guy I have doing this says that the front driveshaft is too long. Also, he says I need a a front slip yoke.

2 questions.
1) Does the 231 Slip yoke get moved to the 242?
2) All the research I've done says the front drive shafts should interchange. Is this wrong. Are there multiple drive shaft lengths between different transfer cases?
 
I don't remember needing to swap front drive shafts on mine. 2000 XJ, 2" lift. I did do a Hack-n-Tap on the rear output of the 242 though. I had a deal on an Adams Drive shaft that fit. Not really needed though.
 
I'm going in on Monday to discuss the point. The shop is kinda small, and generally does good work, but doesn't like doing anything out of the ordinary. Switching out a 231 for a 242 is out of the ordinary. If I have too, I'll get them to put the rear drive shaft in and drive it home in 2wd and go from there.
 
1) There's no such thing as a front slip yoke on these. They are all a fixed yoke on the front and the slip is built into the shaft as it's 2 pieces. The rear uses a single piece shaft with a slip yoke, unless modified with a SYE.

2) There's only 2 different front shafts for the 4.0L, manual and auto. The manual is about 1.5" shorter. You should be able to use both original shafts since you're not changing the engine, transmission, or axles.

It's really a pretty simple swap mechanically and no different than slapping another 231 in there, aside from the linkage. If you want the 'FULL TIME' indicator on the dash to work when in 4H full, though, you'll have to splice in a wire but it's easy on 00-01.
 
So to confirm, assuming my reman transfer case is a 242J and not a 242HD (I haven't double checked, and hopefully the reman firm didn't make a mistake) the rear slip yoke should work fine. The 27 spline output shaft on both the 231J and 242J are the same diameter. The front output yoke on the 242J should fit the U-joints on the double cardan end of the drive shaft and the u-joint at the far end should just bolt into the pinion.

I wonder if something happened when my son blew it up on I-75. He was driving pretty fast and put a hole in the 231J. The torque shouldn't have twisted the whole transmission and engine? If so that could explain why the shaft is too short for the 242.
 
I'm planning the same swap. Only my XJ is a 92, 4.0, 5spd. I want to change the 231 to a 242 and add the SYE. I have to get new drive shafts made anyway due to axle swaps. So changing the transfer case is almost cost free. I've read in other posts that the input splines are the same from 92 to 2001. Can anyone confirm that?
 
There are plenty of write ups on the spline count for a 242/231 swap. I can't confirm that they are always the same. When I was speaking to the reman transfer case builder, he needed the tag number from the 231 to confirm the transmission output spline shaft length and spline count. I would double check the length and spline count for a manual transmission, especially on a early XJ. As far as I know or have researched, there was never a XJ that had a manual and 242 from the factory. Most reman transfer cases can be ordered with custom input shafts, though I don't know if there is a upcharge for a configuration that never had a build code associated with it.
 
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