Transfer Case Input Shaft

Vay

Vay

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Joined
Apr 16, 2020
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Southwest PA
Had my 231 recently explode on me. I happened to have another 231 laying around which I *thought* was identical. Upon removing my old one from my 42rle I noticed that it uses the shorter input shaft while my potential new transfer case has the longer shaft. Three options come to mind: Swap the planetary gears, cut the shaft to a shorter length, or look for another transfer case with a short shaft.

Are the planetary gears identical other than the shafts being different lengths? In other words, am I correct in assuming I can just swap them out if I disassembled both cases?

Is there anything wrong with simply cutting around 3/4" to 1" off of the input shaft? And smoothing off any sharp edges of course. This seems like the easier option.
 
cutting the excess length is an option, just making sure to smooth out the edges as you said. Very important that is done so it doesn’t slice the trans output seal upon installation to the transmission.

If you got the short input gear, the swap would be direct as long as you got one 1995+. The older model gear used in YJs had a different cut and can not be used in a later TJ planetary, just like a TJ input gear can not be used in a YJ planetary. And of course; that applies to planetaries too, you can not swap those across the different transfer case year designations because of the annulus gear installed into the transfer case housing that the planetary indexes around. I only mention this so you don’t assume you can just buy a gear/planetary combo from 1994 and prior and drop it in.

I would not choose sourcing a whole ‘nother transfer case as the solution to this issue, although it is an option. It’s too easy to rebuild and too expensive to buy another one IMO for that to be worth it. But, it is an option if you don’t care about the downsides.
 
You should be able to just swap it out. You won't know if you can't until you do. IIRC the bearing size for the input shaft may be different, that's when you know you can't
 
just noticing I spoke a bit too fast:

yes, as long as both transfer cases are from TJs, you can swap the input gear from one to the other. No issue at all. That is the route I would go if I had the old blown case and new case handy. Assuming of course that the old Case’s input gear wasn’t damaged. And I would do a rebuild during the swap. And an SYE if you don’t have yet but want/need one.

bearing sizes changed with the early and late cut (1994 prior and 1995+) so no issues there, once again assuming the new case is from a TJ. 95+ uses narrow bearing and 1994- uses wide bearing. So wide bearing goes with early cut and narrow goes with late cut.
 
CharlesHS said:
https://www.novak-adapt.com/knowledge/np-nvg-input-gears
There were quite a few variations available for the 21 and 23 spline and short and long shaft.
Click to expand...
There are, but they aren’t as critical as one would think. 03-06 rubis were all short gear 241s regardless of NV3550, NSG370, or 42RLE.

Early models were typically long for auto and short for manual but I’ve seen a few 99 owners say their AX15 had long shafts in the case. However, it isn’t critical, an AX15 never needs a long gear. It’s just that at that point Jeep must have been simplifying the lineup or something. On those 99s with long gears, you can still see the seal rides super close to the transfer case and that a short gear would have done the job perfectly.

so yes, in a way the transmission type is tied to length but there aren’t really set in stone rules and sometimes you can use a longer gear without any issue too.
 
LittleTankTJ said:
You should be able to just swap it out. You won't know if you can't until you do. IIRC the bearing size for the input shaft may be different, that's when you know you can't
Click to expand...
Do you have to split the case housing to swap input shafts. I can’t find a how to swap. Just rebuild
 
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