4wd not working

1988 vacuum disconnect eliminated/moved the connecter over permanently

So i ran about 200 miles of the baja 1000 course last week after the race and 4wd worked perfect. I ran super hard for my xj being basically stock(no lockers) and the road was about as bad as you could imagine so it got beat crazy hard but even through the end the 4wd felt perfect. Then a few days ago i put it in 4wd to pull someone out of the dirt and it wasn't working.

I checked the disconnect portion of the axle and it looks perfect still and the np231 linkage is still functioning. I put the car on jack stands and ran it in 2wd 4hi and 4low and the back wheels spin fine but the front ones don't move a hair. This is my daily driver and there have been no weird sounds or grinding heard like pieces in the transfer case. But it shouldn't run normally if something in the transfer case blew up anyways right?

I regularly drive in soft sand so 4wd needs to be fixed asap so please help! I don't know why the linkages would slip, but could this be a possibility? If so how do i test it or adjust it properly? Thanks

does the front driveshaft spin at all? is the shift linkage actually engaging the transfer case?

i would check to make sure the transfer case is physically in a 4wd mode.

The linkage moves when I move the handle in the cab. I went underneath and watched it as someone shifted the handle and it moved the linkage going into the TC. The front driveshaft does not spin at all right now in 4wd.

Are you actually in low range when you shift into 4lo?

I haven't driven it in 4low to see if the back still functions in 4low gears but ill try in a minute. can't tell with it off the ground because in my eye the tires spin fast in any gear off the ground.

ok problem solved for now. I drove it and the transfer case seemed to be working fine. rear responded correctly. So i jacked it all up again and ran it and took videos of every piece one at a time and reviewed it. The locking mechanism in the vacuum disconnect was just barely missing the teeth. It looked perfect when i took the cover off and even spinning the tires moved everything perfect but the second it went under load it jumped over just enough to disengage. i only saw it when i reviewed the video. I now how to figure out how to keep it in the perfect spot. Next week Im going to pick up a solid axle shaft from the junk yard and ditch this 2 piece crap until i can afford to completely redo the front axle.

did you do this? http://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/

ljobbins said:

The front driveshaft does not spin at all right now in 4wd.

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???

RCP Phx said:

???

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I must have been hallucinating last night at o'dark thirty.
I was positive i watched the driveshaft in 4wd and it was not moving. I was scared the fork was broken but then when i checked it again this morning it was moving so i went through everything again.

90xj06 said:

did you do this? http://www.cherokeeforum.com/f51/free-d30-cad-bypass-91-a-38629/

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I did this a long time ago. When i just checked it this morning everything looked perfect but I must have missed the connector piece the first time with the fork and it was engaged just enough on the inner side of the fork to give me 4wd but then slipped over time of banging it around to disengage. So the fork was permanently engaged in 4wd but the connector piece was not set up under the fork. Now it is...for sure. But just to be safe and stronger, next week I'm grabbing a junk yard solid axle shaft and swapping that thing in.

thanks guys for replying and sorry for my stupidity of just screwing things up the first time.

You know you'll need different seals and need to do more work than just throwing a solid shaft in, right?

I ordered seals for both sides because might as well do both. I am familiar with taking the gears out so that should be fine. And I am just going to take out the fork in the disco assembly so that will be my block off plate. I have read several posts for tricks to remove and install the old seals and new seals. Anything else I forgot or need to know?

Yeah, it's a different seal all together on the passenger side. I don't know all the details but I know you can't just press in the same seal you use on the drivers side since there is no machined surface for it on passenger. I've also heard there is an oil channel that drives oil to the CAD that you would want to block off. Most folks say it's not worth the effort to do this and can just buy a non-CAD 30 and swap the axles with less effort than trying to what you want to do.

dan1977p said:

Yeah, it's a different seal all together on the passenger side. I don't know all the details but I know you can't just press in the same seal you use on the drivers side since there is no machined surface for it on passenger. I've also heard there is an oil channel that drives oil to the CAD that you would want to block off. Most folks say it's not worth the effort to do this and can just buy a non-CAD 30 and swap the axles with less effort than trying to what you want to do.

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Its a major PITA trying to get it to seal. Some have had good luck grinding the axle tube to fit a new seal. I didn't. Mine was resealed twice by me, I even silicon-ed the tight fitting seal in place, I still get a drip every now and then. Finally picked up a non disco housing today. I would save up for a non-disco housing..........

The passenger side the seal is a pita to seal right. I built a tool using a allthread with nuts and washer to try to mimic the jeep tool. It sort of worked since it did seal. It's might have been better to cut a piece of wood to the right diameter. There is a place selling a tool for the cad seal, costs around $150.

I've seen some wright ups that have the passenger side axel being swapped out with a non disconnect axel and a new seal being same as drivers and hammered in place in the pumpkin like the drivers side, no idea if it actually works. Could just put one of those aftermarket the outer axel seals in too.



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Getting a non disco housing is the best way to go. Lots of folks have gone down this road and found the seal just wasn't working well since it wasn't oe and bought a new 30 or upgraded. Only reason I haven't is because I regeared too soon and just don't want to reset my gears on a new housing.

Yeah I googled forever to find part numbers from people who had done the swap so hopefully I got the right seal. I was planning on doing the pipe with a socket or washer pounding through the opposite axle side through the pumpkin to seat the seal. I also got the outer seals. I think they were like 60 or so for both and I figure I could reuse them if I did swap axles in the future(assuming they don't get destroyed).

I would love a newer axle without the disconnect port and a solid axle shaft but 15 dollars for seals and 35 for a junk yard axle shaft assembly is more in my budget right now than the 200 plus the junkyard or craigslist wants for a complete axle.

Thanks for the help and if you guys have more advice I'm all ears.