4WD setup help on 90xj

Well after dropping in a new motor this winter, another set of issues with the Jeep has set in...its a 90 XJ with a 4.0 with a stick.

Problems,

1. When the 4wd is engaged every couple of minutes it will pop out momentarily(split second and slam back in in 4hi), wtf is causing this? Also this gets worse when pulling the 2 sleds up the pass, more stress on the drivetrain...... I hate the engineer who used a vacuum setup for the actuator but I'm guessing this is where the issue is coming from. the drivetrain has about 220k on it and I'd rather put in lockouts but am not dropping 1300 for a warn setup...the damn thing isn't even worth that much. Cost me 180 bucks for lockouts on my D60 under my 88 XJ...and I'm guessing there is no easy way to go about doing this without an axle swap or something I'm not willing to invest in for a DD snowboarding/camping rig....

So my question for you guys, where should I diagnose from first and what may be the most simple issue.... It does not sound like anything coming from the t case, simply a disengaging in the axle.

2. Next issue.... I have put about 6K on her in 4wd up in the mountains this winter and now have a nice vibration that is getting consistently worse and predominantly at 30-40 mph in third gear... there is also a little squeal or whistle coming from the case now at low speeds too... its not loud but barely audible, have to listen hard for it. I'm not going to lie on the hwy i do not go 50 or slower all the time(i go faster). I'm going to start at the u joints, then flush the t case and tranny as well, then to the wheel bearings. I recently did both diffs and have no reason to open them up again after about 15k.

ANY SUGGESTIONS OF WHAT ELSE TO CHECK

NOTE: none of this is felt when out of 4wd... and the jeep is lifted 6 inches with 33x1250's on it and has a ton of weight on the front and back causing a realistic lift of about 4.5-5 in the front. Also have "add a leafs" in the rear for the towing and a tranny drop kit...



One other question...what are your thoughts on wheel spacers. I never have used them but just got a steal on a set of tires and rims but the back spacing brings my tire within about a 1/4 of an inch of the rear leafs and wanted to bump them out a little without getting rid of the rims.... hub spacers a smart way to go or no for those who actually have tried them?

i'd find a solid axle shaft from a new xj or tj. they are cheap, and you won't have any more problems. you won't even notice you did it, until you go into 4wd, and the only difference is that it will work every time.
change the tcase fluid out,
and make sure all your ujoints are good, and that the slip on your front and rear shafts are in good shape. you might look into a slip yoke eliminator for that much lift. i think that'll help out with your issues

yeah I have a SYE on my 88 but have not had time to put one on the 90...

I have not heard about a solid axle shaft swap like that before... what year tj and xj's are they found in? and what is all involved in the mod... I will check in with our local jeep yard and see what they have got...have quite the credit there now.

i did it on my 87, after breaking the 2 piece shaft like you have. any year xj after 90 will work, and any of the earlier ones with the np242 case will, too. the newer ones have stronger shafts, though. i'd look for at least a 95, if you can find it.

will do man I'll be making a call tomorrow for one..thanks a bunch... also would you have any links to visuals of what exactly you are talking about so I can cross check at the yard when I pull them...

is this what I'm looking for?

http://cgi.ebay.com/ebaymotors/Jeep...r_Truck_Parts_Accessories?hash=item4cecdbac4d

setup with axle disconnect is way different...

http://cgi.ebay.com/ebaymotors/Jeep...r_Truck_Parts_Accessories?hash=item4a9d417bd7


am I going to need driver and passenger side setup for a non disconnect? Once again I'd appreciate any help here this is all new territory for me...

I also found this....http://www.therangerstation.com/tech_library/Dana30.htm... I am just unsure how eaxactly the outer shaft will be compatible... if not I could use my current outer and get a hybrid u joint to the inner in need be...that is if possible at all.... I guess it boils down to if I get a solid inner will it slide right in and not cause further modification with the stock system....and will a solid inner setup come with a direct replacement outer that I can just slide the entire unit in and bypass all the vacuum BS without issue.... once again set me straight here....this is me just guessing after a few short reads....

after digging deeper it looks as if I still need warn's kit to do this....is that not correct...seems as if the solid setup needs a blockoff plate and new seals? I'm trying to avoid that cost, if not then great, otherwise I am willing to replace the damn vacuum actuator and any other minor issues for now to get by for a couple more years till i sell it! I don't mind the front spinning constantly eventhough not engaged through the t case.

You remove the 2 piece shaft and coupling sleeve on the passenger side. Replace with the one shaft. The newer axle shafts have the larger spicer 297x joints and the older ones have the smaller 260x joints.

The drivers side shaft does not need to be changed.

The outers should be compatible, so if you switch to a newer 297x style passenger inner, you should be able to use the matching outer, no special parts necessary.

thats what I needed to know... so would this sucker work?
http://cgi.ebay.com/ebaymotors/Jeep...r_Truck_Parts_Accessories?hash=item4cecdbac4d

That would be the one.

Made the switch to TJ axles on my 90 XJ, best thing I have done. You will need to change the seals on the right side and make a block off plate for the axle tube. Or I think Yukon makes a kit for it.

well I found an axle today so that will wait till this weekend, front u joint on the DC joint is def shot(bad), guessing thats where the vibes are from, I'm going to replace all 3 anyways. Flushed the T case and replaced the tranny oil as well. So this weekend I'll know if all is fixed...

also, never heard anything about opinions about wheel spacers for the rear tire clearance.... any of you have any opinions... I already ordered them just wanted to hear personal objections if there are any.

Nik said:

well I found an axle today so that will wait till this weekend, front u joint on the DC joint is def shot(bad), guessing thats where the vibes are from, I'm going to replace all 3 anyways. Flushed the T case and replaced the tranny oil as well. So this weekend I'll know if all is fixed...

also, never heard anything about opinions about wheel spacers for the rear tire clearance.... any of you have any opinions... I already ordered them just wanted to hear personal objections if there are any.

Click to expand...

I'm using a small set of spacers to widen my 8.8 closer to the stock XJ width. Only complaint is that I have broken one of them. I wouldn't go crazy with spacers, since increasing backspacing can increase leverage the wheels have on the ball joints, wheel bearings etc. Using a reasonable amount of spacing is no different than changing to wheels with different backspacing.