NP231

I have a 1994 XJ Sport 4.0 Automatic. NP231 98,000 miles. Its my DD, but I play a little bit when I can.

Transfer case is shot. Chain wore a hole threw it.

I'm assuming they all bolt up, but I'm sure newer have different style plugs, speedo, etc.

So my question is what years fit a 94?
Is there a better tcase that can bolt up without modifications?
Is there a tcase that'll bolt up with minimal modifications like changing electrical plugs etc?

I'm getting one from a scrapyard so I can get just about anything used.

91 to 96 xj is a direct swap. 93 4.0 zj 231 is a direct swap. 97+ xj will work, you will need the driveshaft from the donor as well unless you want to tear it down ans swap out the mainshaft.

Thanks.

Digger87xj said:

91 to 96 xj is a direct swap. 93 4.0 zj 231 is a direct swap. 97+ xj will work, you will need the driveshaft from the donor as well unless you want to tear it down ans swap out the mainshaft.

Click to expand...

You sure?

They switched from a 21 spline to a 23 spline T-case/Transmission the same year they introduced the H.O motor. I can't remember what year that was but i think it was 92 or 93.

He's right on the fence or damn near to it.

91-96 i DO NOT believe is a direct swap.

Well mine is a 94 H.O.

Kingkong0192 said:

You sure?

They switched from a 21 spline to a 23 spline T-case/Transmission the same year they introduced the H.O motor. I can't remember what year that was but i think it was 92 or 93.

He's right on the fence or damn near to it.

91-96 i DO NOT believe is a direct swap.

Click to expand...

91 was the year the HO motor was introduced.

woody
Member
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Join Date: May 2002
Location: NC Sandhills
Posts: 7,209
What transfer case do I have?
The following 4WD transfer cases were utilized on the various XJ/MJ models throughout the production run.

New Process NP207 Command Trac: 2-speed, chain-drive, part-time 4WD. 2:72:1 low-range. 84-86 2.5l 4cyl and 2.8l V6 models with manual or automatic transmissions. 21-spline input. These used a vacuum switch to activate the dash indicator lamp and engage the front axle disconnect. The shift indicator pattern is 2WD > 4WD high range part-time > Neutral > 4WD low range part-time.

New Process NP229 Select Trac: 2-speed, chain-drive, part or full-time 4WD. 2:72:1 low-range. 84-86 2.8l V6 models with automatic transmission only. 21-spline input. The shift indicator pattern is 2WD > 4WD high range part-time > 4WD high range full-time > Neutral > 4WD low range part-time.

New Process NP231 Command Trac: 2-speed, chain drive, part-time 4WD. 2.72:1 low-range. 87-01 2.5l 4cyl and 4.0l I-6 models with manual or automatic transmission. 87-89 21-spline input, 90-01 23-spline input. The older models used a vacuum switch to activate the dash indicator lamp and engage the front axle disconnect. Newer (non-disconnect axle) versions used an electrical switch to activate the dash lamp. The shift indicator pattern is 2WD > 4WD high range part-time > Neutral > 4WD low range part-time.

New Process NP242 Select Trac: 2-speed, chain-driven, part or full-time 4WD. 2.72:1 low-range. 87-01 models with 4.0l I-6/AW4 automatic transmission only. 87-89 21-spline input, 90-01 23-spline input. The shift indicator pattern is 2WD > 4 high range part-time > 4 high range full-time > Neutral > 4 low range part-time.

Common to all New Process/New Venture transfer cases is an round ID tag on the rear case half. This will indicate the model and serial number. OEM Jeep transfer cases are indicated by the "J" designator (ex: NP231 J) and other OEMs had their own designators (C= Chevy, D= Dodge, AMG= AM General etc...) there is some crossover between parts within the various OEMs, but I won't get into that here.

Throughout the production run, input spline counts and other internal specs changed, and must be compatible with the transmission it's mated to. The later model cases (1996.5 and newer) changed styles of rear slip yoke to an internally sealed version. When replacing parts, performing upgrades, or replacing the case entirely, one must take care to insure the new parts/assemblies are compatible with what is in presently."

www.naxja.org/forum/showthread.php?t=101238

Kingkong0192 said:

You sure?

They switched from a 21 spline to a 23 spline T-case/Transmission the same year they introduced the H.O motor. I can't remember what year that was but i think it was 92 or 93.

He's right on the fence or damn near to it.

91-96 i DO NOT believe is a direct swap.

Click to expand...

Positive.

fishinpolejoe said:

New Process NP231 Command Trac: 2-speed, chain drive, part-time 4WD. 2.72:1 low-range. 87-01 2.5l 4cyl and 4.0l I-6 models with manual or automatic transmission. 87-89 21-spline input, 90-01 23-spline input. The older models used a vacuum switch to activate the dash indicator lamp and engage the front axle disconnect. Newer (non-disconnect axle) versions used an electrical switch to activate the dash lamp. The shift indicator pattern is 2WD > 4WD high range part-time > Neutral > 4WD low range part-time.
www.naxja.org/forum/showthread.php?t=101238

Click to expand...

Judging by this info, I say count your splines at a minimum. My 90' contradicts this info, I have 21 spline and vacuum disco. Just saying, count and measure to be sure.

Will do. Have to bring mine to the parts yard as a core anyway. So I'll have it there to compare.

Joshpowell16 said:

Will do. Have to bring mine to the parts yard as a core anyway. So I'll have it there to compare.

Click to expand...

Just curious, was there any signs of that chain blowing up on you ? I'm sure it made a hell of noise when it busted a hole but any noise leading up to it ? Mine has got almost 300k miles and lately I am wondering about that chain, yet they say the 231 is not desireable.

Well I've only had it for 3,000 miles. And I've never owned an XJ before. So as to what's normal or not, I'm unsure of yet. Once I get the new one in I can tell ya for sure.

However, there is a very noticeable sound that I can only describe as a bad wheel bearing , but does not change when weight transfers like a normal wheel bearing noise. It does change with speed. Now that my casing came apart j noticed its very dry. So Im hoping this noise is just from the tcase being complete shit.

There was also a distict noise coming from the tcase when i was going down the highway. It sounded like a loose bicycle chain..just heavier. How ironic considering its a stretched chain anyway. And yes once the casing broke open..it started making a god awful noise lol

Another dead giveaway for me was the day I took it to the cliffs. Put it in 4x4 and well...its basically just bucked n again ironically sounded like a bicycle chain skipping just a lot heavier. N just from research online I figured it to be a stretched chain. 1,000 miles later I figured out I was right when it came through the casing lll

Yeh, I was thinking I would hear it rubbing before it blew out. I'll have to check it a lil closer and check the slop if possible. Hope the junk man has one for you. Lost my go to u pull it yard a few years ago to LKQ's buying them all up and closing the yard to public.

Theres like 50 parts yards around Chicago suburbs and central Illinois... So I should be okay lol. No idea how to check slop. Looked like there was some big bolts that could come off to see inside.

Joshpowell16 said:

Will do. Have to bring mine to the parts yard as a core anyway. So I'll have it there to compare.

Click to expand...

Be forewarned...to get credit as a core, the case has to be rebuildable....yours is not.

It does not have to be rebuildable at a parts yard.

Maybe....no junkyard I've ever been to wanted a core charge.

But hey, if they charge one, then they are making free money, cuz lets say they have a 400 lb engine they are gonna scrap....they charge you 250 for the engine, and then insist on a core back....and as long as it is complete, they still have a 400 lb engine to scrap...so they got 250 free......

Where I shop, they want the core back as scrap weight.