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Clunk from front end and 4 wheel drive disengages

doclouie

NAXJA Forum User
Location
Logan, Utah
I have noticed recently on snowy roads when in 4 high that I will hear a clunck from the front end and then I will loose the 4 wheel drive in the front. It goes back to 4 high no problem but it is random on snowy or loose dirt. So basically I loose the 4 wheel drive after the clunk for a second or two until it engages again. The u joints are good and the drive shaft is not slipping. Axle is full of oil also. The sound is coming from the front axle but I have never heard of this problem before. Does anyone have the same problem or have a clue what this might be? Any ideas would be great. Thanks
 
Same thing happens to my 90. It loses vacuum momentarily while driving which allows the vacuum disconnect feature to disengage (there is a sleeve in the front axles of some XJ's that slides over to join the two axle halves together to form one.) There are ways to fix it. One is replacement parts in the form of vacuum parts, another is a cable actuated disconnect instead of a vacuum ($200 for the kit if I remember right), and someone here recently welded the sleeve in the 4wd position. That works ok and makes it like a solid axle like the one on my 94 XJ. I hear you can also remove the 2 piece setup and replace it with a solid axle on that side to bypass the disconnect. Mine seems to do it sporadically when driving on the highway and comes back on when I let up on the gas.
 
I have the same problem in my 91 and it's that stupid vacuum, but i found it's cheaper to go to a junk yard and get an axle out of a 93+ and swap that in, because the vacuum will just fail again so why fix it and 200 dollors for a cable is a little much when a new(used)axle from a junk yard is 50 to 100 dollors(at least that's the price here.
 
It doesn't have to be a 93+ axle. 87+ XJs with the NP242 came with non-disconnect axles also.
 
Thanks everyone. It sounds like that vacuum thing needs to go. I do have a couple questions though. What year axles will work that do not have the vacuum setup? Are all the mounts the same? If you have done this swap how do you put it into 4 wheel drive? Sorry for all the questions but they are things I will need to know before swapping it out. Thanks again.
 
jmaxj said:
I have the same problem in my 91 and it's that stupid vacuum, but i found it's cheaper to go to a junk yard and get an axle out of a 93+ and swap that in, because the vacuum will just fail again so why fix it and 200 dollors for a cable is a little much when a new(used)axle from a junk yard is 50 to 100 dollors(at least that's the price here.


Have you done the axle swap on your Jeep yet? How was it? What problems did you run into?
 
Four wheel drive is still activated by pulling the handle. The vacuum disconnect is kind of like locking hubs in a way. It reduces the wear on the t-case and other components. The wheels spin in opposite directions if you were to jack up the front end (with the disconnect engaged) and spin a wheel. Hold one wheel still with the disconnect engaged and spin the other wheel and the driveshaft will spin. The disconnect reduces the wear by eliminating some moving parts. The newer axles without the disconnect will spin the front driveshaft (both front wheels turning) all the time when moving if I understand it right, but 4wd will not be engaged without pulling the handle. Sorry if I'm confusing you.
 
doclouie said:
Have you done the axle swap on your Jeep yet? How was it? What problems did you run into?

hav'nt done it yet to mine but i did it to a friend of mine's about a year ago and the only thing he didn't like is the front end is constantly locked in unlike the disco axle it was disengaged when in 2wd, but it never was an major issue until he put a lock-right up there(dumb move) so if you don't mind a little extra turning front end than no big deal. i'm gonna do a hub converson from a CJ when i put mine in so i don't have any issue's with my arb(never know) but i'll let you know how it goes swapping over in about 2 to 3 weeks maybe sooner(hopefully). oh yeah and everything did bolt up just had to cut and cap off excess vacuum lines. and yes 87+ axles will work just check for 242 t-case or the one piece pass. side axle tube, but don't get one with c.v.'s in it.
 
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