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  • September 20, 2021, 02:15:19 AM

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Author Topic: Front Diff and NP231 Transfer Case  (Read 589 times)

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Offline BajaMx1983SX4

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Front Diff and NP231 Transfer Case
« on: August 03, 2021, 06:24:21 PM »
Hi Eagles!

Last week bought a 1983 AMC SX4 Auto trans; & I was wondering if someone swap in a NP231 tc (23 splines) to the stock 998 transmission, keeping the IFS diff?? Thinking to install XJ 4wd lever, linkage & center console; I know these  cases use a slip yoke output shaft, so driveshaft modification will be required.

Thanks 4 ur Help!
Blessings;
G.A.

Offline maddog

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Re: Front Diff and NP231 Transfer Case
« Reply #1 on: August 04, 2021, 07:43:55 PM »
I'm planning on putting a 231 in mine as well once I finish playing with everything else that needs done on Eagle eyes and I'm pretty sure there have been others who have done this swap and if memory serves me correctly there is a slip yoke eliminator for the 231 case so you shouldn't have to modify your drive shaft if I'm recalling correctly.
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Offline BajaMx1983SX4

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Re: Front Diff and NP231 Transfer Case
« Reply #2 on: August 05, 2021, 07:37:36 PM »
Thanks 4 the reply MadDog, i found this post that is very helpfull. Is a np242 swap, 242 and 231 are the same thing, so this let us know it is possible to do!!

https://forums.amceaglesden.com/index.php?topic=46609.0

Offline Canoe

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Re: Front Diff and NP231 Transfer Case
« Reply #3 on: August 09, 2021, 11:22:47 AM »
... 242 and 231 are the same thing, ...
I don't know if you mean that their swap is the same, or that those transfercases are the same. The info I have is that the:
  • 231 4WD is always locked, hence it's always Part-Time 4x4, you put a huge stress on the TC driving on dry pavement (some hop when turning, may gernade).
  • 242 4WD high can be unlocked for Full-Time High (capable/safe on dry pavement) or locked for Part-Time High.

In the following summary table I got somewhere/sometime, I've crossed out the TCs that I wouldn't want.

Offline atmafox

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Re: Front Diff and NP231 Transfer Case
« Reply #4 on: August 09, 2021, 01:43:52 PM »
I might be odd but I actually want a 247.  Not noted above: 247s are 0/100 split by default in their fulltime AWD, they just transfer up to 50% of the power up front if the rear wheels start slipping and function much like a torsen differential so one wheel slipping doesn't steal the power from all of the other wheels.

A 249 is nice as well, with its viscous couple -- but once that wears out (like the 119/129) then you're left with just an open diff.
Mine:
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Ours:
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Hers:
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His:
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Offline Canoe

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Re: Front Diff and NP231 Transfer Case
« Reply #5 on: August 10, 2021, 11:06:53 PM »
I might be odd but I actually want a 247. ...
A 249 is nice as well, with its viscous couple -- but once that wears out (like the 119/129) then you're left with just an open diff.
Those would be my choices, particularly the 247. Except I'm thinking about future part life and maintenance.

Heard of too many viscous TCs ruined when there's a leak that goes undetected and trashes the TC. To me, that leaves out any of the viscous TCs. Although I really missed it when I went from the NP119 of my '81 to the NP128 in my '86. First snow fall was an astoundingly major disappointment; made getting to other than the NP128 was a big thing for me - until I got very decent winter tires (Hakkapeliitta), then viscous was immediately a nice to have, just because. Surprisingly, not even any issues pulling my friends ~30' sailing boat around (in the yard, not enough weight or brakes for the road...). Left a few people with their jaws hanging down when they saw it pull away from the sling lift without any discernible effort. I have to admit, it surprised me too. I was expecting to have to make some noise and work for it, but no.

So having an Open Centre, with Low, and lockable in low, with lockable in high as a bonus (not sure I'd ever use it), seems the best compromise. When/if I finally go there, I'm tempted to try and keep the on-dash 2wd/4wd selectable with vacuum, but that's more failure points and I haven't even looked into if that is even possible.

 

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