NP 231 Transfer Case Upgrades?

01TJ-Blues

01TJ-Blues

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So my old NP 231 is growling at me after a nice weekend of playing in the woods. Time for a rebuild after a mere 188,000 miles. That said are there any upgrades that should be done or possibly a lower ratio available before I order parts and begin the rebuild?

Any input it greatly appreciated!
 
Terraflex was the only one providing a lower ratio, but they stopped making the terralow awhile ago. Rebuild it and move on if it did what you needed it to the last 188k.
 
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JB Conversions sells a wide chain upgrade and a planitary gear set upgrade. If it were me, Id go with their super short SYE as well to get just a little bit more DS length.

I also understand money doesn't grow on trees.

To counter with a realistic approach, a refresh is all that’s needed for most TJ/LJ NP231 owners with that kind of milage. The NP231 is a problem free case for most members here.
 
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I just installed the JP Conversions Super Short SYE and can tell you, even without driving it yet, it's a worth while upgrade. I'd consider going to a 6-pin planetary as well if you can find one cheap on eBay.

I ended up going with the hub and groove setup off of an earlier NP231 because they came with a synchronizer setup to make going between 2Hi <-> 4Hi smoother but I already had the parts in my shop for it.

I have most of the parts for a wide chain kit and standard SYE kit that are used that I'd sell you cheap. I can try to get all the pieces together and get pictures for you this evening if you like.

Thanks
Grant
 
disjaukifa said:
I just installed the JP Conversions Super Short SYE and can tell you, even without driving it yet, it's a worth while upgrade. I'd consider going to a 6-pin planetary as well if you can find one cheap on eBay.

I ended up going with the hub and groove setup off of an earlier NP231 because they came with a synchronizer setup to make going between 2Hi <-> 4Hi smoother but I already had the parts in my shop for it.

I have most of the parts for a wide chain kit and standard SYE kit that are used that I'd sell you cheap. I can try to get all the pieces together and get pictures for you this evening if you like.

Thanks
Grant
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My TC already has an SYE so just a rebuild and maybe the wide chain upgrade I’d say.
 
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Looking to lower my gears in the NP231 and add the yoke elimination
Has anyone resumed making a similar half case kit like they use to or just the guts

I would do a rubicon transfer case if I found one
My Jeep is a 98 tj five speed
I just wanna crawl with the Jeep have big farm I run it on
 
Brokendreams&axles said:
Looking to lower my gears in the NP231 and add the yoke elimination
Has anyone resumed making a similar half case kit like they use to or just the guts

I would do a rubicon transfer case if I found one
My Jeep is a 98 tj five speed
I just wanna crawl with the Jeep have big farm I run it on
Click to expand...
I regeared to 4.88s with 33s and eventually 35s and crawl fine.

What's your axle gear ratio?

There's a whole thread on crawlboxes. Two or three good pages of info and then squirrel!

https://wranglertjforum.com/threads/np231-doubler-crawlbox.58658/
-Mac
 
Right now it has 307 gears witch I’m looking for a quick fix . I have a dana44 for the rear in a parts Jeep I have to order the weld up kit so since I’m opening the transfer case I don’t care I I blow 1200$ to lower it.. I have the two wheel low set up to add.. did one before and loved it ..
 
If you can find a 241 or a Terralow...unicorns...or want to find a used D300...also rare...or spend thousands on an Atlas or billet D300...

Best bet is regear. Lots of resources and information on these forums.

-Mac
 
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macleanflood said:
If you can find a 241 or a Terralow...unicorns...or want to find a used D300...also rare...or spend thousands on an Atlas or billet D300...

Best bet is regear. Lots of resources and information on these forums.

-Mac
Click to expand...
Yea like I said I have a rear danna 44 I need to pull and weld up b
macleanflood said:
If you can find a 241 or a Terralow...unicorns...or want to find a used D300...also rare...or spend thousands on an Atlas or billet D300...

Best bet is regear. Lots of resources and information on these forums.

-Mac
Click to expand...
i would buy the two speed atlas tomorrow and say the heck with it but I can’t find one.. I have the low 98 skid plate I think I would ad a little body lift for it.. And it would mount in with a little fab work

Everyone says 16 weeks out I want it next week lol
Honestly the atlas is the only one I will add if I replace my stock case
 
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Brokendreams&axles said:
i would buy the two speed atlas tomorrow and say the heck with it but I can’t find one.. I have the low 98 skid plate I think I would ad a little body lift for it.. And it would mount in with a little fab work

Everyone says 16 weeks out I want it next week lol
Honestly the atlas is the only one I will add if I replace my stock case
Click to expand...
I waited 5 months for mine....
 
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