np231 shifting into 4hi on the street

I've had my front shaft disconnected (from the front diff) and ziptied to the control arm for the longest time since I haven't been able to make it out wheeling and wanted to cut down on some vibes and parasitic drag. Just recently, I noticed a weird thumping and banging under my feet when only a few blocks from the house. I turned around and went back home and looked around but didn't have time to fully diagnose. It did it again a few days later when I tried driving the jeep again.

It was at this time that I discovered that the tc had been engaging 4wd randomly. I could tell from marks on the shaft where it was rubbing on a bolt on my drop brackets. I went ahead and hooked up the driveshaft fully and drove it around and I'm for sure getting some hopping and binding while driving so I'll just go pull the shaft completely for now.

It's a 99 aw4/231 combo. What should I look for here?

On your 99 the main shaft is held in place with multiple lock rings at the rear housing, and one of those is probably broken. This allows the main shaft to slide back and forth a bit, and the splines for the chain sprocket are lightly engaging

Damn.....really hope that's not the case. FWIW, I forgot to mention it does have an SYE. I don't know if that has the same lock ring setup or not.

My googlefu was a little weak last night. Do I have to buy a 231 rebuild kit for the snaprings or can they be sourced individually? Anybody have a wide chain, 6 gear planetary, and 2lo kit for sale cheap? Might as well have fun while I'm in there.

Try to find a parts catalog for your generation (all the online diagrams are for the pre-96 models). I think they all use the same lock rings which are J6134488 but the last time I checked at the dealer they were sold individually but were on back order nationally (awaiting production) and not available at the time. Crown did not sell them when I checked their catalogs.

Well I bought the small parts kit and worked on it over this last weekend. Didn't find any broken pieces or broken snap rings inside. The wear looks normal and everything is as it should be. I went ahead and replaced the shift fork pads and snap rings that were removed and threw it all together. I'm still shifting into 4wd on the street though. I could even feel it while doing a tight u-turn on the street. The front lunchbox was really givin' it hell on that one.

Does anybody have any ideas?

looseness in the shifter pawl? or maybe shifter linkage adjustment?

I would disconnect the shift linkages between the body and the TC and try it to see what happens. There may be too much movement at the engine/transmission mounts, the linkages are too loose and/or not properly adjusted.

The linkage seemed good. Obviously we had to disconnect it to drop the case and split it open. I'll try pulling the linkage off later this week. I probably need to have it ready to drive on Wednesday when I won't be able to car pool so I'll have to just pull the shaft for that day.

So I pulled the linkage off and drove it around today. I think I caught the feeling once or twice that it was in 4wd. Tomorrow, I'll pull the front shaft, jack up the rear and put her in drive. Then just climb under and watch the front yoke.

DeftwillP said:

So I pulled the linkage off and drove it around today. I think I caught the feeling once or twice that it was in 4wd. Tomorrow, I'll pull the front shaft, jack up the rear and put her in drive. Then just climb under and watch the front yoke.

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Really bad idea since your concerned about it going into 4WD !!!!!

How is it a bad idea? I know it's not the safest to be under it while in drive but the front shaft is out and the rear wheels are off.