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Thread: NP231 question

  1. #1
    That guy!!! Ghostfire's Avatar
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    Default NP231 question

    Are all jeep NP231 transfercases the same. I want to swap out the all wheel drive transfercase for the NP231 in my zj.

    Any advice or info

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    Mandolore blizzard's Avatar
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    If the engine sizes are the same and you transmissions are the same, you'll be fine. for instance driving a straight 6 in both vehicles and a standard in both, the T-case will fit the same. but if both are straight 6's but one transmission is a stick and the other an auto they wont work. the pain in the a$$ way to fig out is to count the teeth on the transmission and match it up with the grooves on the t-case where they connect. Hope this helps, I just got done swapping out my t-case about a month ago. If you have any questions feel free to ask.

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    G.I. Grandpa SGM O's Avatar
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    Ghostfire, not clear what you are trying to do...replace an NP242 Selectrac T-Case with an NP231 Commandtrac T-Case or vice versa? They are not the same. That does not mean that it won't work, but it is not the same as doing a 231 for a 231 out of a differant Jeep. I agree with what Blizzard said, that if you are talking the 4.0L six and same transmission I think you are all set, but the Selectrac was only offered with a four speed automatic transmission in the XJ, ZJ and WJ it was never offered in a Wrangler.

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    Sunshine and Rainbows Rubitron's Avatar
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    Why switch? Is the 242 broken? I seem to think I read that it's not as strong as the 231. Is that true? Does it have a 4:1 low range, the name would suggest, like the 231 having almost 3:1, and the 241 having 4:1. Or am I way off?

  5. #5
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    Quote Originally Posted by Rubitron View Post
    Why switch? Is the 242 broken? I seem to think I read that it's not as strong as the 231. Is that true? Does it have a 4:1 low range, the name would suggest, like the 231 having almost 3:1, and the 241 having 4:1. Or am I way off?
    way off on the gearing thinking part. other wise my 271 would have like a 7:1 low range. the 241 in the rubicon has 4:1 but not the standard 241. i had a 241 in my dodge and i think it was 2.72:1.

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    That guy!!! Ghostfire's Avatar
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    I want to get rid if having all wheel drive. I'm not a fan. I want the option of 4wd not having at all times. I am starting to part together a tranny to rebuild and I want to figure out what tcase to use. This winter I am buying a crate engine for my zj to get rid of my high milage engine.

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    G.I. Grandpa SGM O's Avatar
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    What engine are we talking about? I ran an "88 XJ for 292,000 miles, a '94 ZJ for 295,000 miles and a '98 ZJ for over 260,000 miles all with the 4.0L, automatic and the NP242 Selectrac transfer case with no issues other than replacing the clutch pack in the '98 at about 190,000 miles. The NP242 is a good transfer case and is what was standard in a ZJ if you ordered the 5.2L V-8 and was an option with the 4.0L 6-cyl which cam standard with the NP231 Commandtrac. Both over a 1:1 2wd and 4wd high range and a 2.72:1 low range, but the NP242 also offers a Full Time High range where the center diff is open allowing you to run 4wd or AWD at any speed on any road surface. The Part-Time setting it performs just like the NP231 and provided better traction. The shift lever for the t-case should read "2WD - 4 Part time - 4 Full time - N - 4 Lo"

    Now there is also the NV249 Quadratrac transfer case that was offered in the ZJ which is a full time AWD system with a low range, there is no 2WD option. SO your Grand Cherokee would be in AWD all the time and your t-case lever would read "Full Time - N - 4 Lo" if I remember correctly. If not maintained properly these can be problematic, but there is more to the system than just the t-case, I think there was some sort of wheel sensor, axle slip reader that told the system what wheel to send the power too...this system was replaced with the current Quadratrac II and ultimately the Quadradrive system in the WJ and WK Grand Cherokee.

    Found this article when I Googled the T-Case number for Quadratrac as I couldn't remember it.

    http://jeephorizons.com/tech/tcase.html

  8. #8
    Sunshine and Rainbows Rubitron's Avatar
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    Quote Originally Posted by SGM O View Post
    The Part-Time setting it performs just like the NP231 and provided better traction.
    Why do you say that? When I bought my XJ there were two that were very similar but one had a 231 and the other a 242. I got the 231 because I thought it was stronger (think I read that somewhere), and it seems the 231 has a much larger aftermarket following. If it performs the same in part time, what would make provide better traction?

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    Tattooed Jeeper Irish_Assassin's Avatar
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    Most ZJ's came with a 249 with 242's and 231's being an option. Dont hold me to it but I am pretty sure all V8 ZJ's came with the 249 the 242 and 231's were options in the I6.


    Ok Ghostfire... if you truely have the same Jeep as I do I'm going to venture to say that you have the NP249 TC which is a decent TC but the viscous? coupler goes bad. The 231 and the 242 are much better options. The 231 has the capability of using a SYE but the 242 will neen a HNT. The 242 will have 2, 4 part time, 4 full time, N, 4lo. The 231 will have 2, 4 part time, N, 4lo. A lot of ZJ owners will do the 242 swap because the speedo sensor is plug and play. This does not happen with the 231. Ideally you would want to try to find a TC out of the same year as your ZJ. At minimum try to stay 95 and higher. There are pleanty of write ups on JF concering this. I would suggest that you go there and read up. I know of a good one for you I'll see if I can find it and post it for you. BTW if you do swap in a 231 I have a ZJ 231 shifter bezel you could have
    Quote Originally Posted by usnavymitchells View Post
    I am officially a Huge Steeler's Fan!
    97 ZJ Murdered Out! (SOLD ), 5.5" Clayton L/A's front and rear, 242 swap, HP30 & 8.8 w/ 4.88's & Eaton ELocker's F/R, 35" Goodyear Wrangler MT/R's with Kevlar.

    Grand Cherokee Owners
    http://www.militaryjeepers.com/commu...php?groupid=44

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    Tattooed Jeeper Irish_Assassin's Avatar
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    Quote Originally Posted by usnavymitchells View Post
    I am officially a Huge Steeler's Fan!
    97 ZJ Murdered Out! (SOLD ), 5.5" Clayton L/A's front and rear, 242 swap, HP30 & 8.8 w/ 4.88's & Eaton ELocker's F/R, 35" Goodyear Wrangler MT/R's with Kevlar.

    Grand Cherokee Owners
    http://www.militaryjeepers.com/commu...php?groupid=44

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