Tools and tips for upcoming NP231 work

thomat65

thomat65

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Sometime soonish I'm going to be splitting my transfer case to install the TeraFlex 2Low kit. While I'm at it I also plan to install the Savvy shifter cable.

The NP231 service manual describes how to do an overhaul and says to discard the snap rings, yoke nut washers, and a few o-rings. So my first question is: does anyone know where I can find new ones or what the part numbers are? Or is it fine to reuse those parts?

My transfer case has a little over than 190k highway miles. The previous owner apparently never took it off road and my off road trips have been very mild in the months that I've had it. But I have no idea what service has been done to the transfer case if any. So my second question is: with that many miles how much should I be considering a complete overhaul? Bearings and everything, just the chain, or don't worry about it until I split it? Part numbers are helpful.

Finally, what tools will I need for this work? My list so far includes a 1 1/8" socket, lock ring pliers, some gasket maker, and red and blue thread locker. I already have allen wrenches and smaller sockets and wrenches and of course ATF. I'm guessing a regular 12 point socket will work on the 10mm 12 point bolt, right?

Anything I'm missing or should consider? I guess it wouldn't hurt to go ahead and replace the u joints. I don't want too much scope creep though.
 
JB Conversions has the parts needed as you rebuild the transfer case.

Half moon wrench will help you get at the upper nuts that hold your case to the transmission.

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The 1/2" & 9/16" wrench is the one you need.
 
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cpwolf said:
You’re doing a rebuild, so taking it off , skid off, transmission dropped some, I didn’t see there was a room issue. Ratcheting socket makes life easier, but didn’t seem tight to me.
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Yep, no special wrenches for me.

I’d say good snap ring pliers are what I wished I had. Mine all sucked.
 
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thomat65 said:
So I should plan on going ahead and doing a rebuild? I don't know why I wouldn't since it'll be the most convenient time to do one, but I wasn't sure if it was necessary yet or how to make that decision.
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I’m not saying that, but I was asking if you’re cracking it open etc? Either way, you’re pulling the TC, and you can lower it to get it the bolts pretty easily.
 
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Special wrenches definitely not needed. Also, no point rebuilding if you aren't having issues or noises. These things are durable.
 
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I agree with @Lou. Solve the problem when you have the problem. If you have to some day, just lower the TCase to reach the upper bolt. Easy
 
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As others said the half moon wrenches are not NEEDED but as I said they can be helpful. but yes I've done it with regular wrenches and sockets also.

I'd put new seals and o-rings in it since you have it torn down. But as others said these things are pretty durable.
 
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If you do a complete overhaul, there is a bearing or two in there in blind holes. I've heard of guys using a dremel or die grinder to get at the bearing for removal. I bought this:

https://www.amazon.com/gp/product/B07FV54MVL/?tag=wranglerorg-20

I bought my parts from a transmission parts supply in KC. I did have to modify the u-puller legs in the puller kit to sit flat and true for it to work correctly.
 
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