np231 swap

[GreenGrandV8]

i have a zj with the np249 t-case tryin to swap the 231 in but the 231 i got has a big vacuum switch on it that my zj doesnt have.... can i still use it??

[calvynandhobbs]

Sounds like you got an older 231 out of a XJ or YJ that had a vacuum disconnect front axle. As far as I know you should be able to just plug that spot since you don't need the vacuum for your front axle.

[GreenGrandV8]

yeah... thats what i figured. its a 23 spline which is what i need. another thing i noticed is the speed sensor on it looks different but i think where it sits into the case itself it might be the same... im just tryin to figure out if i should try and use it or bring it back to the junk yard and try and have them find me a different one..

[calvynandhobbs]

The older ones have a mechanical speed sensor and at some point they put an electronic speed sensor in there so I don't know if you'd be able to get the older 231 to work at all if you want to see how fast you are driving. I don't have much knowledge in that department, but you may make the swap a little easier if you find a newer 231 that is set up with the same type of speed sensor and everything as is currently in your Jeep. I just found this thread about the swap you want to do. Looks like there are some extra links to do more reading and it appears there may be some input shaft differences in the different years for you to think about.

http://www.jeepforum.com/forum/f13/zj-np249-np231-swap-question-596306/

[GreenGrandV8]

yeah im going to be swapping the input gear for sure.. i been doin a lot of research.. one thing that crossed my mind is i was wondering if maybe i could just swap that tail shaft piece with a newer one with the other sensors in it if that would work or not... i dont really know why it wouldnt.. what do u think?

[gearhead1985B]

yeah im going to be swapping the input gear for sure.. i been doin a lot of research.. one thing that crossed my mind is i was wondering if maybe i could just swap that tail shaft piece with a newer one with the other sensors in it if that would work or not... i dont really know why it wouldnt.. what do u think?

i don't know if the vss is the same on the np 249 but the case you got sounds like an early yj case swaping the tail shaft is a possibility but i don't think it will work the vaccume plug thing is for your 4x4 indication so you can swap it for the electronic switch from an xj and your 4x4 light will work

[GreenGrandV8]

well hopefully this will solve my problems..... i had a white xj in my yard that friends have been using for parts, and the guy i bought it from said it was a 96. looked at it yesterday and its a 3/94 and the transfer case gear cut change was between 94-95 so fopefully this one is still the early gear cut so i can swap the input shaft.. ripped the case out today.. only took like an hour and a half.. came out nice. so im hoping ill be all set. thanks for the info guys. i need to become a real member so we can go wheelin.. i live in canterbury and dont know many people to wheel with out here..

[BlacXJeep]

Come on out mang!

[kirksjeep]

The electric switch from your ZJ will replace the vacuum switch with no problems, I swaped out the one in my YJ when I did away with the vacuum disco.  The speed sensor should screw in also.  I have done several SYE conversions and the kits are all the same reguardless of the speedo type.  Have you looked to see if the transfercases are the same length, if not you will need new drive shafts?  Just a thought.