NP231 internals question

[freedom_in_4low]

I'm picking up a used transfer case from a 2000 XJ later to replace mine that I broke the front housing on during an SYE install. Since XJ's are notoriously beaten on and my internals are known to be good, I'm planning to swap mine over and just use the housing.

My only question is the annulus gear in the housing. The FSM describes it as non-serviceable and that it stays with the housing, but it looks like it's just held in by a big internal snapring. Anybody know what reason would be for not swapping it over? Or, are they a typical wear item that I should even concern myself with before throwing my input gear and planetary into it?

 

[ac_]

If it were me, I would tear the new xfer case apart and see what it looks like. Don't just assume it is beat. It may or may not have had a hard life. It might actually be in better shape than yours. If that is the case, put it back together and swap it. On the other hand if yours was ok before you broke the case just replace the case parts and use yours. I am not sure what the actual hear is you are asking about, but compare them to see if they are even worth swapping out. Transfer cases unless you beat the shit out of your truck really don't get used that much or that hard compared to like your diff or transmission.

When I did the SYE on mine, I actually did it in the Jeep, but when I drained the fluid it was burned and black. I don't even think it was the right fluid, but I cleaned everything up sparkling and it has been fine ever since. It now has a SYE with new ATF +4 synthetic and clean as a whistle. I didn't have to replace anything except the fluid and of course the stuff to do the SYE. it is happy now. I am still using the original chain and it is a 98 just shy of 200K.

I bet you will be fine, just take it apart and look it all over first.

Oh yeah sorry about your case, that sucks!

 

[freedom_in_4low]

If it were me, I would tear the new xfer case apart and see what it looks like. Don't just assume it is beat. It may or may not have had a hard life. It might actually be in better shape than yours. If that is the case, put it back together and swap it. On the other hand if yours was ok before you broke the case just replace the case parts and use yours. I am not sure what the actual hear is you are asking about, but compare them to see if they are even worth swapping out. Transfer cases unless you beat the shit out of your truck really don't get used that much or that hard compared to like your diff or transmission.

When I did the SYE on mine, I actually did it in the Jeep, but when I drained the fluid it was burned and black. I don't even think it was the right fluid, but I cleaned everything up sparkling and it has been fine ever since. It now has a SYE with new ATF +4 synthetic and clean as a whistle. I didn't have to replace anything except the fluid and of course the stuff to do the SYE. it is happy now. I am still using the original chain and it is a 98 just shy of 200K.

I bet you will be fine, just take it apart and look it all over first.

Oh yeah sorry about your case, that sucks!

You're right, I'm just getting all my ducks in a row before I tear into it.

The annulus gear is the way the FSM refers to the fixed outer gear that surrounds the planetary set. In this pair of images, the left side shows the gear, with orange arrows, in a beat up teralow 4:1 case i have in my garage. I used that photo because the planetary is out so it's easy to see, and the gear appears to be pressed in. In the right, you can see my case and I've circled the gap in the internal lock ring that seems to suggest the gear might be removable.