Pehlke1985

Hey guys i just bought a 231 off a guy that is from a 86 I believe and I am building a 2000. Did I make a mistake??? Will it fit for sure or can I make it fit what do I have to do. I tried searching but nothing that I need has come up. I know it should bolt up but the case seems to have 4 vac lines coming off of it. Is that for the old dis connect style. Any help or tips would be great. Thanks.

Garvin

You sure it's a 231 from an '86? From what I've seen, '86's only came with the NP207 and NP228/229. If it did come from an '86, the input splines are different ('90 and older AW4's and any non-AX15 manual had 21 splines), your Jeep is a 23 spline input. If for some reason the NP231 was behind the older automatics (A904) then it would be a 23 spline but I have yet to see an NP231 coupled to that transmission.

The vacuum piece on the back of the transfer case can just be ignored. You can take it off and put a plug in it if you really want or just leave it on there, just cap the lines to make sure nothing gets inside the transfer case.

Pehlke1985

I know its a 231 the tag says anyway haha and the guy said it was an 86 but who knows. I counted the splines and seems to be 23 on the trans side thats what I'm looking for right?

freegdr

http://www.jeep4x4center.com/jeep-tr...case/index.htm

Lead Foot

What do you currently have in your vehicle? A bad 231? or are you converting to 4 wheel with trans you have too? You can swap out the input shaft and planetary gears from a np242 or other 231 that has the 23 splines... 91 and newer. I just did this swap. Very easy

Garvin

Mid-94 and older interchange, they changed the splines of the planetaries on the late-94 and newer NP242 and NP231's (I did this swap from an early '94 NP242 into a '90 NP231). If you have the 23 spline then it was from an '89 and newer AX15 or '91 and newer AW4, maybe the guy meant '96 instead of '86?

Pehlke1985

I have a 242 that is going bad. And want a 231. I have a 2000 with the automatic (AW4?) Sorry im new to jeeps this is my first one and still learnig about them. So I canswap out my main shaft from my 242 if the 231 is not 23 splines?

Pehlke1985

Im pretty sure it was older than 96. Looked to be anyways its hard to say.

xjmarc

If it has the vacuum on it it's a 91 or older and doubt you could swap the input from the 242 but I'm sure someone knows. Also you won't have the 4wd switch so your part time light on the dash won't work. The older ones used a vacuum switch on the firewall and newer have the switch in the case.