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np231-->np242

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Old Feb 14, 2014 | 02:50 AM
  #1  
JerrytheJeep's Avatar
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From: San Jose
Year: 89
Model: Cherokee
Engine: 4.0 I6
Default np231-->np242

Id like to swap the 242 in my rig to my dd, which has a 231.
my rig is a 92 with an aw4, and np242
my dd is a 98 with an aw4, and np231

I've done some research, here's what I've found:
Both transfer cases have an input shaft that is 23 splines: the lengths of these shafts however, are different.

the np231 has an input shaft length of 1.550", and the 242 has an input length of .840" according to this site
My concern is that the shafts may not fit the "new" transmissions properly.

I believe, according to this Novak Conversions page, that the output shaft of the aw4 is "medium" for both years, (This is wrong, sorry. I misread the information on Novak's site, which was referring to input shaft lengths. Im now more confused...)
so it shouldn't be a problem mating the cases to the "new" transmissions because the output shaft lengths will have not changed.

Clear as mud? At this point I've been able to confuse my dad halfway through our conversations, so at least I'm learning

I think I'll pull the tcase out of my rig tomorrow anyway and measure it myself, I'll be renting a clocking jig in the near future so it will happen eventually.

Anyone have any thoughts on the subject?

Last edited by JerrytheJeep; Feb 14, 2014 at 03:22 AM.
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Old Feb 14, 2014 | 03:05 AM
  #2  
TwoXJS's Avatar
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From: Wilton, CA
Year: '93
Model: Cherokee
Engine: 2.5L I4 (Mercedes Turbo Diesel planned)
Default

I'm definitely no expert, but I think the input shaft length might be how far it actually goes into the case. I can imagine the 242 would be shorter since it would seem to have more parts inside seeing as how it's a full time case with differential action to work properly. That's just what my brain is imagining, so there's a good chance I'm wrong! Lol

It seems like it'd be a fairly straight forward swap to me, and one that I'm also considering doing someday after I move to where I want to, which is snow country. Montana, specifically. Only thing I could see changing would be the shifter bezel inside and POSSIBLY the shifter gate piece under the center console. Again, probably wrong on that one....

EDIT: And whadda know, I was wrong on the shaft length. Lol I was imagining how far into the T-Case it went, not into the transmission. So, disregard the entire first section!

Last edited by TwoXJS; Feb 14, 2014 at 03:09 AM.
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Old Feb 14, 2014 | 03:18 AM
  #3  
JerrytheJeep's Avatar
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From: San Jose
Year: 89
Model: Cherokee
Engine: 4.0 I6
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Originally Posted by TwoXJS
I'm definitely no expert, but I think the input shaft length might be how far it actually goes into the case. I can imagine the 242 would be shorter since it would seem to have more parts inside seeing as how it's a full time case with differential action to work properly. That's just what my brain is imagining, so there's a good chance I'm wrong! Lol

It seems like it'd be a fairly straight forward swap to me, and one that I'm also considering doing someday after I move to where I want to, which is snow country. Montana, specifically. Only thing I could see changing would be the shifter bezel inside and POSSIBLY the shifter gate piece under the center console. Again, probably wrong on that one....
Sorry, I suppose I should specify. The input shaft "length" I'm referring to is the length of the shaft that slips over the output shaft of the transmission. Which I guess is the same thing as the depth, tomato tomahto. That input shaft is actually a gear, which you can see on the link I attached to "Novak Conversions" which is this

http://www.novak-adapt.com/knowledge...nput_gears.htm

I do plan on swapping over the linkages and bezels, as well as the speed sensors due to a change in their design. This is actually part of a 2wd to 4wd conversion. I have yet to install the linkage in my dd so this will be a good time to do it. I figured why not switch the cases while im at it.
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