NP242 in a JK?
 

Just curious. Has anyone ever switched the NP231 transfer case in a JK for a NP242 transfer case (optional full-time 4 hi)??

I was kind of curious about that myself. I had one in my XJ and it worked well in snowy conditions where you went from snow covered to clear pavement repeatedly. It would be great if it would bolt right up. Might be an issue with the speedo output.

That's one thing I do miss about my KJ. The full-time four wheel drive option.

I ordered my 06 Liberty Renegade with the Selec-Trac t-case. That vehicle was an absolute monster in the winter time with the full time 4 hi option and Blizzak tires. It would be a really sweet addtion to the JK if it were optional. This will be my first winter in my 2011 so we'll see how it compares. If it was a direct swap or an almost-direct swap I would certainly consider doing it.

The JK gets its speed data from the ABS wheel sensors.

Was the t-case discussed here pretty durable? Wondering if it had any shortcomings.

I don't know too much about the history or durability of this case. I know it isn't considered to be as strong as the 231 because of it's differential that allows it to be full-time. It isn't for the rock-crawling people, but IF it would fit, it would sure be nice for longer distance winter travelling folk.

Psssst JK's don't come with NP231 t-cases.

Sharp eye! I didn't pick up on the way the question was worded.

Sorry about that! Is it the 241? Sometimes the hands are faster than the brain.

The 231 had a higher torque input rating then the 242. But I've never heard of one failing without serious abuse.

It's the one thing that I miss from my KJ & XJ, made them completely unstoppable in the winter. If the roads got that bad, just drop it in part-time and keep on going, the ESP on the KJ worked wonders in full time. (not so much in 2wd).

I've searched a bit but I've never found anyone that's swapped one in a JK, just lot's of former KJ/XJ owners like me whining lol

It does have a 23 spline input in the 242j version (gotta find one with the right shaft length though), which would match the nsg370, but the 242 supposedly doesn't like being mated to manual transmissions (in full time anyway, part time wouldn't be any different then a 231/241). But I think any problems would be caused by driver error.

If a diesel JK doesn't come out by the time my warranty is up, it's high of my list of things I'd like to do.

I haven't seen any input torque ratings for the transfer cases. The second digit refers to the case size/strength.
Would this be related to input torque rating?

I'm currently considering trading in my KJ (which has an NV242) for a JK, and this has been the one very sore point for me about the JK. I'd be very interested in doing an aftermarket transfer case swap on the JK to put an NV242 on it if possible. For a vehicle that costs what the JK does (more than the KJ), I don't understand why the NV242 wouldn't be offered-- its not like they need to develop a new transfer case and worry about making up the engineering costs only a small subset of buyers elect the option.

I live in the NE Cleveland area, and drive through the snow belt daily in the winter. As others have stated, the full-time 4WD while retaining the option of part-time when it gets really bad has been incredible. (btw, in the spring we get comeasurate amounts of rain to compensate for the lack of feet of snow, so my KJ has experienced on-road water fording). In my experience, the full-time 4WD vastly improves handling even on dry and wet pavement-- it's very noticable how much better the KJ sticks to the road when you're using the front tires to pull through a turn rather than just pushing them straight ahead from the back. I'm really not looking forward to having to constantly throw the JK in and out of part time 4WD when the roads are patchy or the weather is sub-optimal, but not yet many inches of snow.

Oh, and the NV242 should definately fit (given appropriate adapters I expect). If I'm not mistaken, the JKU is actually longer and wider than the KJ.

When I was looking at the JK model the part-time case was a bit of a sore point. Make no mistake, I really like my Sahara, and I have plans to keep it for a long time. But once it is off warranty I would seriously consider the swap if it is practical. It is interesting to read the comments about how good the Liberty is in the winter with the 242. I felt like mine was unstoppable and I really put it to the test up here in some pretty bad winter storms and severe cold.

The 242 (full and part time) is a fine transfer case. It is longer than the 241 (part time) due to the location of the speedo gear in the tailhousing and having the slip yoke internal. Advance Adapters does provide a plug kit for the Atlas that plugs the speedo hole for applications like the JK that do not have the speedo sensor located in the t-case extension housing. I assume that same plug will fit in the 242.

But again the 242 is a few inches longer than the 241 and the main shaft is different. The 242 has the slip yoke located in the transfer case whereas the 241 has the slip yoke located in the driveshaft. You would have to purchase a short shaft kit for the 242 and a driveshaft to match if you don't have one already. In addition, if you purchase a used 242 without a short 23 spline input shaft, you'd have to also purchase the correct input spline during your build.

So it is possible, but you would end up investing several hundred or thousands of dollars to build a t-case that is still weaker than the 241.

I had a ZJ with full-time 4wd that I wheeled heavily. I eventually converted it from the 249 to the 242 to have the option of 2wd and full time 4wd. It did as well as I would have expected offroad and I didn't have any issues with the installation. Well I did learn that the 249 had a short 23 spline input shaft while the 242 I purchased had 21 splines. I was able to swap the input shafts which saved me a lot of time and frustration. I had shortened the rear driveshaft, but the slip yoke was still internal and the main shaft on the 249 and 242 had the same count so it matched up fine.

The jk is longer than a ZJ, WJ, or WK. (not sure about the newest grand.)
Width-wise it is about 1" or so more narrow inside. Exterior is about the same I think.

As for the 242 working with a stick, I think I recall the ZJ guys swapping in the AX tranny with some using a 231 and others a 242.

Check with Tera Flex as I think they made or custome made a 2-Lo and a 4:1 for the 242 case.

I wonder if it is as simple as swapping input shaft and away you go?

I would enjoy a full time setting as well, but not at the expense of losing my 4:1.

But then, just add a rubi-crawler in the mix for us auto folks and we're set.

Thanks for the reply. I don't think strength would be the deciding factor in my situation. Unfortunately, my JK won't see a lot of hard offroad use. There just isn't a lot of real trails in my area. There are too many lakes and swamps in the way. My rig will be built as more of an expedition JK. It is also my DD, and my long distance driver, as in let's drive across Canada or let's drive to San Diego. It will see winter bush roads, summer bush roads, and winter roads across our many lakes. The 242 would hold up just fine. Maybe once the drivetrain is off warranty I will consider this swap. It sounds like it is possible, or at least worth doing some more checking into.:cheers:

I have been investigating the issue for a long time now. I will be definitevely doing the swap if I am assured it works. After having full-time Land Rovers and seeing the 360-degree versatility of my friends' Pajero with the Super-Select, a part/full time t-case is really the best option out there.

I had some exchanges with David from Novak-Adapters who was very kind in explaining that they are working on a "slip yoke eliminator" available sometime soon for the 242 transfer case (all versions), with an electronic speed sensor output integral to it (which doesn’t matter for the JK), as well as available rebuilt cases to which the kit can be applied.

Unfortunately I have not had any further update since last time we talked about it, this was around end April/May this year. I'd assume they have more work done on this, but he has not replied to my further queries .... :sad2: so I wait.

Thanks for the information. It is nice to know I wasn't the only one thinking that a full-time option would be nice. I wonder what Jeep/Chrysler/Fiat would think about this plan for the future?? It only has to be an option. Not everyone is interested in 4:1 case for crawling etc.

anyone actually tried the swap
 

Guys,
has anyone actually tried to swap the jk transfer case for the 242 (or 242hd)? I was told ther isn't enough room to fit the box in the jk. I am seriously considering a JK instead of my old Wj but the lack of 4HI got me worried. The european JK with the diesel engine and auto box has a very uneaven torque output and the back wheels keep on spinning any time you step harder on the throttle. I can't imagine any winter situations with the current transfer case. On the other hand both the 242 and my Wj quadradrive box work just fine when things get slippery so my question is really can you have any of them in a JK Unlimited?

The JK has 4-hi. It handles the winter very well for me.

I did this swap! I have use T-case out of KJ 03. Fits well but a little works is necessary.

Attachment 479701 Attachment 479703

Attachment 479704 Attachment 479705

Attachment 479706

Details! Write up a how-to, I've decided to keep my JK for awhile and this is tops on my list of mods!

It will not be easy to describe. My English is not so good. And this is a little more complicated theme in my own language.And,only five photos per post.
The main problem is of length,. NP242 is too long, and has a slip yoke instead fixed yoke ,if you want to use stock drive shafts. No one manufactured SYE kit with short shaft.
I have long thought up that model NP242 use. Finally it became the best NP242J from KJ Liberty. It has the same input shaft, same length. It has 32 ​​teeth front and rear outputs and the same position switch. It is important for the proper function of the ESP.

First:
shorten the main shaft. Spline length -1,25" (32mm),drill and tap thread 3/8 or 10mm.
Then make washer and weld it to the inside of yoke.

Attachment 479726 Attachment 479727

Attachment 479728 Attachment 479729

second:
modification of range selector
The position switch is the same. Five positions. NP241 only skips the position of Full Time.
The value in position Full Time in the Selec Trac,JK's electronics does not know. It is necessary to weld on a little a bit material on the third surface of range selector. The switch must be in this position to give the same value as in the 2WD position.

stock 242
Attachment 479731

Modified
Attachment 479732

2WD
Attachment 479733

Part Time
Attachment 479734

Full Time
Attachment 479735

Neutral
0,21

Lo Range
0,06

Last, but still not resolved. It is necessary to rotate the direction of the shifting. Everything works, only the lever is backwards in 2WD and shifting is forward.

Attachment 479736 Attachment 479737

Even after this modification, the new t-case is longer than Command Trac. It's not a problem for JK Unlimited but I do not know how the 2dr.

241 - 14,56" (370mm)
242 - 17,70" (450mm)

Attachment 479740

What tcase they using in new grand? Get that its awd and they put behind hemi so should be strong enough (unless differ for hemj) but none the less grand has same engine and tranny and I've seen em wheel them through moab and the rubicon

Here's a nice overview

Jeep Transfer Case Rebuilt Quality Factory Transfer Cases, Save Money! - Drivetrain.com

Thanks for write up! You basically had to make your own slip yoke eliminator.

I dunno how well the extra length would work in my 2dr :(

Either way, bookmarked for when the warranty runs out lol

Anyone else ever try this?