NP242 to NP231

PaulJ · Apr 27, 2005

Can I swap from one to other without needing a different length drive shaft? Also, are the any issues if the 231 came off of a manual and is replacing the 242 on an auto? Both are the same model year '87.

cherokeefun · Apr 27, 2005

I think it is all about the spline shaft count. and I believe that your 242 has a 21 spline count but the 231 no idea.

Fudd · Apr 27, 2005

I just did the same swap last week... On mine the 242 was coupled to an auto with 21 splines and 231 with a 5spd with 23. I swapped trannies as well so this wasn't an issue for me. The driveshaft lengths were different but that was more with the 5 spd being a shorter length than the auto I'm not sure if the tcase swap alone would affect this or not.

PaulJ · Apr 27, 2005

Anyone have a definite answer to my question?

Jerms · Apr 27, 2005

I have done it on an 88' i took the 231 from an xj of the same year it was a 5spd, and swapped in my 88' which is auto and came with a 242, the two tcase are almost identical from the outside and there is no difference in d-shaft length that is caused by tcase the difference in d-shaft length is from tranny's cause the 5spd is a lot shorter.

Jerms

ZPD · Apr 27, 2005

You won't have any problem. I just did it last weekend. I believe all 242's are a 21 spline so make sure that the 231 is a 21 spline too.

uvaldetxj · Apr 27, 2005

it's not just a bolt in swap. i'm going to buy a jeep wagoneer limited next week with a broken 242. i'm going to put in a 231. the spline counts are different. you have to tear apart the t-case and swap shafts. it shouldn't be too hard. but it does take some effort. here's a link to a site explaining it.

http://hobbyguild.com/jeep/index.html

woody · Apr 27, 2005

PaulJ said:
Can I swap from one to other without needing a different length drive shaft? Also, are the any issues if the 231 came off of a manual and is replacing the 242 on an auto? Both are the same model year '87.

Yes the cases should swap just fine... IIRC I used the same driveshafts swapping over from 242 to 231 (though I did put on a YJ slip yoke for increased clearance) "supposedly" the 242 slip-yoke is the same length as the YJ yoke -apprx 1/4" longer than the 231 XJ yoke...it just lacks the extra angle clearance the YJ yoke offers. Below 4" lift or so, this isn't a worry... use whichever yoke looks smoother :dunno: I'd get the adjustable linkage rod with the 231 if possible, but those parts may be the same?

"You won't have any problem. I just did it last weekend. I believe all 242's are a 21 spline so make sure that the 231 is a 21 spline too."

I believe the 231 and 242 both went from 21 to 23 splines around model year 1990. If the donor has a 4.0l & 5 speed, and the tranny is a Peugot BA10/5, IT HAS 21 splines; If it is an Asin-Warner AX15, IT HAS 23 splines. AW4 automatic trannys around 89-90? One can only guess without pulling it to check.

One can (if they have to) swap input shafts to match the trans output spline count... but that's a bunch more work than finding one that mates right up. Plus (I think) that the 231 internals changed some over the years, so a 87 input shaft might not swap right in to a newer case. Newer cases also lack the mechanical speedo drive that the 94(?)-older need

Another minor detail, the 231 from an 87 and other older ones may have a vacuum switch (that tells the front axle disco to shift and lights up the 'part time' dashlight.) The 242 has a wire & connector for the lights. When I swapped in a 231 from a 242, I just capped the vacuum ports on the switch. I hate dash lights anyway, so NBD to me.

HTH clear things up

Woody

xj-grin · Apr 27, 2005

woody said:
One can (if they have to) swap input shafts to match the trans output spline count... but that's a bunch more work than finding one that mates right up. Plus (I think) that the 231 internals changed some over the years, so a 87 input shaft might not swap right in to a newer case.

All 242 and 231 input gears are interchangeable, so the swap from 21 to 23 spline is not that big a deal. However, the 23 spline gear I am using appears to be out of something other than a jeep, as the pilot bearing for the output shaft that rides in the input gear is bigger, and jeep part nos. won't fit. I am investigating whether 241 input gears are the same, and trying to figure out where to find an input gear pilot bearing for the one i've got. These kind of wierd issues are common with New Process/Venture cases, so be prepared for some oddities...

falcon556 · Apr 28, 2005

xj-grin said:
All 242 and 231 input gears are interchangeable, so the swap from 21 to 23 spline is not that big a deal.

What about gear tooth cut. There are two, pre-'95 gears and post-'94 gears.
If the cut is not the same, they will wear each other out.
The input gear has to match the planetary gears and they have to match the annulus gear which is built in the case and cannot be swapped.

xj-grin · Apr 28, 2005

falcon556 said:
What about gear tooth cut. There are two, pre-'95 gears and post-'94 gears.
If the cut is not the same, they will wear each other out.
The input gear has to match the planetary gears and they have to match the annulus gear which is built in the case and cannot be swapped.

Well the guys at Novak adapters that sold me my input gear told me that ALL input gears were interchageable between 231 and 242 cases -- I haven't heard anything about differing gear cuts, and the gear they sent me slipped in fine to both an 88 and 91 case front. That being said, I'm not certain my input gear IS from a 231 or 242 as I can't find a pilot bearing that will fit it listed under those models... :wierd:

blue95xj · Apr 28, 2005

Why is everybody going to the 231 when i thought the 242 was a better t-case considering they swapped one into a xj in jp am i getting something mixed up here or is it just depending on what you want out of your t-case?

JeepSpeedRacer · Apr 28, 2005

This is a wierd thread. In my experience with a 1994 NP231 and a 1998 NP242, I can safely say the input gears ARE NOT interchangeable.

I found that I could not swap the input gears from a 231 to 242 and vise versa. They are different sizes.

However, as to the original point made by the initiator of this thread, yes you can swap the whole 231 with the whole 242 as long as the spline counts are the same. If the spline counts are different, Advance Adapters (or a junk yard) would have an input shaft (input gear, actually) from the SAME MODEL transfer case to get you the right spline count.

falcon556 · Apr 29, 2005

xj-grin said:
Well the guys at Novak adapters that sold me my input gear told me that ALL input gears were interchageable between 231 and 242 cases

http://www.novak-adapt.com/catalog/231_input_gears.htm
The Novak people need to check their own web site.

xj-grin · Apr 29, 2005

:wave:

falcon556 said:
http://www.novak-adapt.com/catalog/231_input_gears.htm
The Novak people need to check their own web site.

Damn, I guess I'm lucky they sent me one that at least the cut was right, although it doesn't inspire confidence that they will be helpful in finding me a pilot bearing that will work...

Sorry for the SPOBI guys, and thanks for straigtening it out, Falcon

NP242 to NP231

PaulJ

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cherokeefun

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Fudd

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PaulJ

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ZPD

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