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np242 from 87 XJ fit in 98 XJ?

Mudderoy

Mudderoy

NAXJA Forum User
Location
Katy, Texas
I have found a NP242 out of a 1987 XJ. Will it fit in a 1998 XJ?

What questions should I ask, spline count, shaft length?
 
Well hell. I found it on craig's list for Houston. 100k miles for $125. I was hoping to find a unit I could use while I repaired my original. I'll keep looking. Thanks a lot for the quick replies!

Here is what I found after my quick post:
1985 - 1989
Select-TRac, 21 spline input,
27 spline rear slip,
tow piece tail housing,
fixed front yoke, 1.750" speedo, hole,
tow wire shift indicator on tail housing,
.750 exposed input shaft.

1996 - 2001
Select-Trac 23 spline input,
27 spline rear slip,
fixed front output yoke,
1.750" speedo hole,
one piece tail housing w/rubber boot,
four wire shift indicator located above shift lever.
.840" exposed input shaft
 
FoMoCo said:
IIRC they went to the 23 spline t-cases in 91 when they changed to the HO
Click to expand...

Yes, that is correct. I just helped a friend do a 21-23 spline swap on his 242. No biggie...
 
FoMoCo said:
IIRC they went to the 23 spline t-cases in 91 when they changed to the HO
Click to expand...

exception being in 1989 1/2, a 5speed ax-15 used a 23 spline 231 case.

but for the aw4, a 21 splined 231/242 was used until 91.
 
to chhange over the input shaft you also need to change the front bearing in some instances, and parts do not interchange between 231 and 242 cses
 
muckleroy said:
I have found a NP242 out of a 1987 XJ. Will it fit in a 1998 XJ?

What questions should I ask, spline count, shaft length?
Click to expand...

Won't fit, wrong input, wrong output.
What you need is a 242 from either 97-01 XJ or 96-98 ZJ.
You will find that the ZJ being more expensive than the XJ is more likely to come with a 242.
Do not use a 96 XJ 242 if you can help it, although identical in every other respect they use a 2 wire switch and different wiring.
 
rockwerks said:
to chhange over the input shaft you also need to change the front bearing in some instances, and parts do not interchange between 231 and 242 cses
Click to expand...

In this particular instance we didn't have to. We put a '93 231 input shaft into an '89 242 transfer case...both from an AW4.
 
rogersjeep said:
i think you can install your old input shaft into the (new)t-case and it would work.
Click to expand...

Nope! The teeth of an 87 gear will not match a 98 case even if they look like they will. Different profile.
 
falcon556 said:
Won't fit, wrong input, wrong output.
What you need is a 242 from either 97-01 XJ or 96-98 ZJ.
You will find that the ZJ being more expensive than the XJ is more likely to come with a 242.
Do not use a 96 XJ 242 if you can help it, although identical in every other respect they use a 2 wire switch and different wiring.
Click to expand...

You'll be hard pressed to find a 242 from a ZJ. I've been looking for one for over a year. Anyone that has one wants a lot for them... The majority of the ZJ's came with POS 249 Fulltime allwheel drive..... just garbage!
 
ScottyDog said:
You'll be hard pressed to find a 242 from a ZJ. I've been looking for one for over a year. Anyone that has one wants a lot for them... The majority of the ZJ's came with POS 249 Fulltime allwheel drive..... just garbage!
Click to expand...

I bought two 242J cases one from a local yard, another from a forum member a couple of years ago.

The bone yard had a bunch on the shelves, I picked the one with the lowest mileage.
http://car-part.com/
has a bunch but, as always the prices shown can be ridiculous.
I paid a little over $200 for mine.
I don't think there is a shortage.
 
Bringing this back from the dead, as it seems to have the best answers to my question.

I'm going to be installing a NP-231 from a 96 XJ into my 89. Right now I've got a 242 in it. I know the input gear is going to be wrong. So.....I've heard back and forth that yes/no I can swap the input gear from the 242 into the 231...or can't. Anyone have a definitive answer on this? I'd rather go find a gear before I start tearing stuff apart if I need to.....

1989 Cherokee
4.0L
AW4


Thanks!
 
Brett M said:
Bringing this back from the dead, as it seems to have the best answers to my question.

I'm going to be installing a NP-231 from a 96 XJ into my 89. Right now I've got a 242 in it. I know the input gear is going to be wrong. So.....I've heard back and forth that yes/no I can swap the input gear from the 242 into the 231...or can't. Anyone have a definitive answer on this? I'd rather go find a gear before I start tearing stuff apart if I need to.....

1989 Cherokee
4.0L
AW4


Thanks!
Click to expand...
NO!!!!!!!!
The tooth profile is different between pre and post 95 TCs
If you do it any way, you'll find that it actually fits, before too long the TC will be trashed because the teeth ate themselves up.
 
falcon556 said:
NO!!!!!!!!
The tooth profile is different between pre and post 95 TCs
If you do it any way, you'll find that it actually fits, before too long the TC will be trashed because the teeth ate themselves up.
Click to expand...

Is there an input gear that I can buy that will work with my old AW4 and a newer TC?
 
Brett M said:
Is there an input gear that I can buy that will work with my old AW4 and a newer TC?
Click to expand...

No, the input gear meshes with the planetaries and the planetaries with the large annular ring which is part of the case and not replaceable.
At least that is my understanding.
 
Brett M said:
Looks like Novak has what I'll be needing. 21 spline, short length, late style input gear for a 231, with the right cut too. :greensmok
Click to expand...

Glad to hear that, it must a custom made gear.
Good luck, let us know how it works out.
 
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