NP 231
 

I went to change my transfer case fluid today and didn't have the right size wrench. Anyone know what size wrench the drain and fill plugs the NP 231 takes? I'm gonna have to pick one up to chage it out. Also any tips or tricks on changing out the fluid?

I think it's 1 3/16", but i typically use a pair of channel locks or large adjustable wrench.

Park the rig nose high to drain, by removing the lower plug. Then level the rig and fill through the top plug till it starts to weap out. Use ATF.

Thanks, I tried a 1 1/8 and a 1 1/4 but I do not have a 1 3/16. I wasn't sure whether it would be that or if it was metric like a lot of other parts on the xj. Anyone else verify the size before I buy the wrench tomorrow?

i`m almost 100% its a 32mm

I've got two options here, I'd like to know for sure before I buy a wrench. I'm thinking it's not the 32mm because that works out to be about 1.2598 inches and a 1.25 wrench was too big. Anyone out there with a NP 231 wanna go out and check for me please?:help:Thanks for the input.

No one knows?

Yep, I bought a 1 3/16" socket to do my 231 and it worked perfect.

i remember a long time ago, before i had many tools, i drove my wrangler to sears, and we went to the parking lot with a few sockets to find the right one.

don't over fill the t case, it seems to be a common though that more fluid is better, i used to think so to, don't jam a bunch of fluid in and plug it as quick as possible. this will cause seal leaks, especially in diffs also. the fluid should be level with the fill hole, don't plug it till its done drainig back out the fill hole after filling.