Grinding/Clunking/not fully engaging in 4 low

So recently I bought a 1992 Cherokee 4.0 automatic that needed a transfer case rebuild. Instead of trying the rebuild out right I found a used np 231 that was compatible. The guy I bought it from said it engaged 4hi and 4 lo with no issues when it was removed. Well I just got done installing this newer np231 and it goes into 4 hi with no issue but when I try 4 lo it grinds and clunks. Now I'm certainly not a master mechanic nor a 4x4 I'm more along the lines of this is my first 4wd automobile ever and mechanically I just try stuff out.... sometimes it works other times not so much.So with that being said I have actually no clue what's going on inside of this transfer case. Is there internally a reason for 4 hi to work and 4 lo to not work? Perhaps this is just a linkage issue ? Any response from someone who has any knowledge on this will be greatly appreciated.

Maybe I should also note that 4hi works like a charm no noises no issues

The only difference between 4-Hi and 4-Lo is the forward planetary. Probably missing a pad on the forward shift fork.

First thing to do is shift the mode lever by hand from underneath, and see if the T-Case will engage 4-low. If it does, the 4x4 shift mechanism needs adjustment. If the symptoms persist, as suggested, it might need new shift fork pads at which time you might want a fresh chain also.

Transfer cases are fairly simple to work on, not a lot there to get lost on. Not like a transmission, plenty of videos out there on disassembly and rebuilds.

Could just be shifter linkage as Tim_MN said. That's were I would start.
Wasn't there something about shifting to 4 low needed to be from neutral or not at speed?
I forget what the book said, and never think about it when I do use 4 low.


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Do you have the transmission in neutral coasting forward at 3 - 4 mph while you are trying to shift your TC from "N" to "4LO"?
I know this may be a dumb question, but then again it may be your only problem.

I'm confused if the grind/clunk is the noise it makes when you're trying to shift into 4-low, or the noise the TC makes after you have shifted into 4-low.

If its making the noise when you try to shift it, do as was said...2-4 mph, transmission in neutral, then shift from 4-high to 4-low.

Have you gotten under the Jeep to look at your t-case linkage. This is what I found when I did (er, I mean "had to") due to similar problem.

I had to replace the little green pop-ins in ALL the linkage arms. Easy with the t-case out...harder with it in. Secret is a little heat and a good pair of pliers. The linkage is very easy to adjust and tweak too. There are also some pretty slick and simple aftermarket shifters.

Good luck

So today I tried to adjust the linkage which didn't really get me anywhere. I adjusted as instructed by the service manual (and a couple other ways)and it just doesn't seem to want to get into 4 low. It went in at one point but grinded in and popped/clunked out shortly after leaving me in a neutral state. How "sloppy " is the linkage supposed to be? There seemed to quite a bit of play .

Disconnect at the transfer case and shift it there and see how it does. Had one once that the trans mount was sagging so bad it refused to go into four low.

Boostwerks eng. Sells a kit to change the linkage design. I made my own version. The shift quality is night and day.

So your trans mount was sagging huh ? I guess now would be a good time to also say this jeep has a 3 inch lift with 1 in t case drop. I didn't think I'd have to mention it but after thinking about it I guess the drop would affect the linkage . Perhaps I mistakenly posted this on the wrong forum

Its possible the linkage is out of adjustment