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Unread 02-17-2014, 06:36 PM   #1
mtidwell
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1988 YJ Wrangler 
 
Join Date: Oct 2007
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NP231 input shaft long and short? change?

Ok Here is the deal. I have an 88 yj with a 4.2 and a tf999 auto transmission. NP231 transfer case as we know.
Well I bought another transfer case from a guy that had a slip yoke eliminator in it. It was out of a 1992 yj with and AX15 and a 6cyl.
I read up some and was told they were the same, both were 23 spline.


I pulled my transfer case and first of all trans fluid came gushing out of the transfer case when i broke the seal from the TC to the Transmission.
Is that normal? I think it is , I put it together , but it was dry at the time . I think i just use RTV there when i put it back together. its like a slip yoke inside there right ?( not the issue just curious)

Well now i see that the transfer case i got has a input shaft that is about 5/8 inches long. The transfer case that i pulled out is about 2 1/2 inches long.
they match up and will bolt up and all but its not right. The splines match.

So what do i do now? Change the input shaft from one transfer case to the other? how do I do that?

is it easier to do the input shaft , planetary? or SYE ?

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Unread 02-17-2014, 06:43 PM   #2
mtidwell
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looks like maybe i can just swap planetary with the input shafts?
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Unread 02-17-2014, 08:22 PM   #3
Anticanman
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Is there enough spline on the output shaft to engage the transfer case?

Swapping the SYE from one case to the other would be much easier than swapping the input shafts. I've done it once before for a xj guy buying a TJ case.
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Unread 02-17-2014, 08:25 PM   #4
mtidwell
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yes, it engages , but keeps leaking fluid , its not going in far enough to seal?

I have been reading , looks like i can just pull the planetary? and swap them,

like this but doing the entire planetary?

http://mallcrawlin.com/forum/showthr...-swap-write-up

the SYE swap what would that take? tearing it all all apart and starting over? honestly that intimidates me. haha
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Unread 02-18-2014, 07:32 AM   #5
Why J?
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Swap the front inputs or move the SYE to your case. Its not terribly difficult, if you can pull a transfer case you can rebuild it. I would replace all the seals and bearings while you are in there. Rent a seal and bearing install tool for the job.

Might think about throwing a 6 pinion planetary in it and a wide chain kit.
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Unread 02-18-2014, 08:03 AM   #6
fishadventure
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Quote:
Originally Posted by mtidwell View Post
...it engages , but keeps leaking fluid , its not going in far enough to seal...
Yes, it seals on the shaft. If you search some and read on here- I have seen a couple of good write-ups on the issue you describe. Not really complex.
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