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Anybody got a NP231J from a YJ laying around that they would like to sell

MoparMan

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Dec 8, 2012
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Location
Hayden, AL
I'm looking for a whole complete NP231J from a YJ. One from a TJ might work work too. My YJ is a 4 cyl 5-speed. After my front driveshaft come out a while back and knocked a hole in mine, I got a 231 from an AMC and it's not working out.

Or does anybody know someone thst could weld up the hole in my original case?

I'm located in Hayden, AL
 
Do you have any pics of the damage?

I have one, but it has the Tera-low 4:1 kit in it. So the front half is different, which is probably the side you need. The planetary gears are messed up in it, those tera-low kits just didn't hold up to hard use. It still has some salvageable parts in it though, like the sye and it has a 2w low selector in it.
Also it is a 27 spline input. Yours may be a 23 seeing how it is behind a 4cyl, I'm not real sure about that though. Either way I may can help with damage too.
 
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Yes, the damage is in the front half. And yes, mine is a 23 spline input. I'm pretty sure my planetary gear is still good. Would it work with the parts you've got?
15942963557038397602789752440966.jpg
 
Do you have any pics of the damage?

I have one, but it has the Tera-low 4:1 kit in it. So the front half is different, which is probably the side you need. The planetary gears are messed up in it, those tera-low kits just didn't hold up to hard use. It still has some salvageable parts in it though, like the sye and it has a 2w low selector in it.
Also it is a 27 spline input. Yours may be a 23 seeing how it is behind a 4cyl, I'm not real sure about that though. Either way I may can help with damage too.

Would my 23 spline input/planetary gears work with what you've got? Where are you located?
 
I live close to Stoney.
The housing won't work, the half you need anyway. Everything else would work. I've repaired some aluminum oil pans that had holes knocked in them and they turned out ok. I could try to fix that one if you want me to.
 
It is rare to have the 23 spline on the 2.5. Most of those I have came across were 21 spline. Is that why the AMC case isn't working out?
 
I live close to Stoney.
The housing won't work, the half you need anyway. Everything else would work. I've repaired some aluminum oil pans that had holes knocked in them and they turned out ok. I could try to fix that one if you want me to.

Ok, sounds good. Send me a pm with a phone number and good time to call or text you. Thanks
 
It is rare to have the 23 spline on the 2.5. Most of those I have came across were 21 spline. Is that why the AMC case isn't working out?

Nah, that's not the issue. I put all of my parts into the AMC case. It worked for a little while, but then started to act up.
 
Nah, that's not the issue. I put all of my parts into the AMC case. It worked for a little while, but then started to act up.
I'd dig deeper into what's acting up. Bent shift fork, shift pads, linkage out of adjustment, stretched chain. Those are all incredibly common issues wit 231's. But they are very easy/cheap fixes.
 
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I'd dig deeper into what's acting up. Bent shift fork, shift pads, linkage out of adjustment, stretched chain. Those are all incredibly common issues wit 231's. But they are very easy/cheap fixes.
Yeah, I've already taken it apart 4 times looking for the problem. I can't figure it out, so my next step is to take it to a professional for them to lool at it. Just thought I would see if I could find another case that was in working order.
 
The really weird part is, it will work fine in 4 lo. But in 2 hi and 4 hi it's like it kicks in and out of gear.
 
You probably know this, but depending on how modified the jeep is, like it has a body lift, linkage out of adjustment could cause that. Trans and motor mounts too. If you have taken it apart then you probably know what to look for inside, like the pads on the shift and mode forks.
 
You probably know this, but depending on how modified the jeep is, like it has a body lift, linkage out of adjustment could cause that. Trans and motor mounts too. If you have taken it apart then you probably know what to look for inside, like the pads on the shift and mode forks.
Yeah, the linkage is definitely not out of adjustment. It very well could be a shift fork though. The pads are all fine, but it could be bent just slightly enough for me to not notice.
 
Disconnect the linkage, shift it by hand and see if it still does it. That'll eliminate one thing.

It's been a minute since I've been in a 231. But, if i remember right, you can actually install one of the shift forks backwards and it'll do what you're describing.
 
It's been a minute since I've been in a 231. But, if i remember right, you can actually install one of the shift forks backwards and it'll do what you're describing.
I thought about that, and maybe it is upside down. Wierd thing is, when it's not installed into the Jeep and it's just laying in the floor it works perfectly.
 
I thought about that, and maybe it is upside down. Wierd thing is, when it's not installed into the Jeep and it's just laying in the floor it works perfectly.
Yea, you apply some actual torque to it and if it's not full seating the shift ring it'll pop out. I bet that fork is bent or not in correctly. There really isn't anything in the physical case itself that'll cause any issues as long as their isn't a gaping hole in it.
 
Yea, you apply some actual torque to it and if it's not full seating the shift ring it'll pop out. I bet that fork is bent or not in correctly. There really isn't anything in the physical case itself that'll cause any issues as long as their isn't a gaping hole in it.

Gotcha
 

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