Axle, driveshaft, or transfer case problem?

Okay, I really need to figure out what the issue is with my Jeep and I can't afford to just throw new parts at it. I need to know where the problem lies. Please help!

It's a 1989 XJ Pioneer, 4.0, 4WD, automatic, NP242 transfer case. 145,000 miles on it. Just bought it a month ago.

This is going to be a bit long, but I want to describe the problem as accurately as I can.

I started noticing the Jeep was wobbly when making a turn, left turns were a little worse. It felt like I was driving over bumps when turning, even if the road was smooth. On u-turns, it was worse, it felt like it was in 4WD because the tires would hop and skip a little. The steering wheel did not wobble, just the rest of the Jeep. I also noticed the Jeep would wobble side to side a little bit when slowing down to a stop or starting from a stop when driving straight.

I had no money to fix this right away, but still had to drive it. It started getting worse (I think largely because of the horrible construction zones I had to drive through where they left huge potholes in the road).

Then one day, the problem changed. (Note: I am not 100% sure this isn't two separate things.) The wobble when turning got much less severe. It felt like I was only hitting one bump when turning instead of three or four and sometimes it didn't do it at all.

BUT, the wobble when driving slowly and straight got much, much worse. It now feels like one of the wheels is out of round. It feels like I am driving over large bumps when I'm driving under 35 mph. Over 35 mph I can still hear it and feel it, but it smooths out mostly. The whole Jeep rocks side to side when going slow. There is now a very large vibration that goes along with the bumpy feeling. Also, the speedometer needle bounces in sync with the wobble and vibration until it get over 35 mph, then it too smooths out with the rest of the symptoms.

The problem is definitely related to the vehicle's speed, the vibes/wobble slow down and get bigger as I slow down and vice versa.

This problem does not occur all the time, though! Only after I've been driving it a bit and usually starts after I get it up past 45 mph. The speedometer always bounces, though. And it may be my imagination, but when the new vibe/wobble is less, the old wobble on turning feeling is worse.

I've checked over the front end as best I can. Everything there seems solid. There is absolutely no play in the hubs or the u-joints that I can see. There is no slop in any of the other components that I can tell. The wheels spin freely with no trouble or noise, except a small clicking sound that sounds like it's coming from inside the axle. The rear wheels are the same, they spin smoothly and quietly and have no play in them. And the wheels are not bent.

Now I suspect it's something on the axles, but I also wonder about the transfer case. It was suggested to me that it was stuck in 4WD. But I can tell the difference when it is really in 4WD. And when it's jacked up, the axles spin freely and independently from the other. However, the transfer case does leak and when I bought it, it was 2/3 of quart low on fluid and made moaning sounds in 4WD and didn't want to come out of 4WD easily (it works better now that there is fluid in it). And then there's the speedometer thing, which comes from the transfer case.

Sorry that was so long. Any thoughts would be greatly appreciated. Thank you!

Ok, if you crawl under the front end with a bright spotlight and carefully examine the axle u-joints what do you see? Does it look like rust dust is coming out from under any of the caps?

Did you jack up the front end and grab the tire at 6 and 12 and try to rock it in and out? At 9 and 3 and rock it back and forth?

you obviously have a problem and are WAY PAST the time to stop driving it until you can determine the problem and repair it.

x2 on the u-joints. $35 bucks for the "high-end" ones at adavanced.

I did do the grab the tire and wiggle it test. At 12 and 6, it is solid. At 9 and 3, the wheels do move, but like they're making a turn, the whole brake assembly and the tie rod move with them. This is supposed to be this way, right?

The u-joints are visibly fine. They don't look new, but they do look in good shape, just slightly greasy, no rust or powder.

Believe me, I wish I could stop driving it until it is fixed. The stress of driving it like this is driving me crazy. But if I can't drive, I lose my job. I have another vehicle that needs work, but I'm in the same spot with that one - I don't know exactly what's wrong with it and only have a very limited amount of money to fix it.

I have to get this right the first time. If I spend the money on the wrong thing, I am screwed. But it's looking like I'm going to have to gamble anyway.

Thanks for the replies.

Stupid question, but I'll ask anyway... have you checked your lug nuts?

Tires in good condition? Checked the pressure? Possibly a problem with a belt? Have you tried rotating the tires front to rear to rule them out?

Have you measured your Toe In/Tow Out? Should be 1/8" Toe In.

If you suspect that it might be stuck in 4WD, remove the front drive shaft and see if the symptoms disappear.

I replaced the front axle u-joints. It made no difference.

I almost want to say it's coming from the rear axle. (It's hard to tell because the springs are worn out and the shocks aren't the greatest, so I feel any bumps and wobbles through the whole Jeep.)

It's something that's grabbing or not turning freely and then releasing, over and over, I can feel a slight drag now when it does it. So I don't think it's the tires or wheels. Plus it comes and goes, with it being worst after driving over 45 mph.

The lugs nuts are fine. I tried to measure the toe-in. Hard to do accurately by myself, but it measured zero toe, which I've read in many places is correct for this transfer case.

I have a couple hundred left to fix this now. Hubs? Front or rear? :shrug:

Do the free things first.

Jack up the A** end and put it on stands. Have a friend rotate the tires while you observe the tread to see if there is any "S" in the pattern.

Pull the wheels, pull the drums, inspect the rear brakes.

Swap the rear wheels left to right and drive it to see if anything changes.

Okay, in the past week I drove around a few days without the front driveshaft. That made no difference.

I replaced the tires with some nearly new ones. The new tires helped some, but the problem is still there. I had suspected that whatever the problem is was wearing the tires and making it worse, it seems that was so. By the way, when the tires were swapped, the wheels all got moved around and the problem still feels the same.

I had an alignment done. It was slightly out of toe, which they fixed (and that didn't change the problem). The caster is off and the camber is off on the right front. I can put up these numbers if they'll help at all. They didn't adjust these. The techs said they didn't see any problems with the steering/suspension components, but I don't know how closely they inspected them.

Let me ask a simpler question. Could anyone list ALL the things on either axle that could cause it to feel like a wheel is out of round or I'm driving over bumps when driving straight? (But it isn't the tires or the wheels.) Forget about the turning issue for the moment.

Thanks for the help so far.

I'd start by making it wobble, stick your head out the window (Safely) and see if you can see the front wheel wobble any.

Have someone get in the driver seat with the key on and the engine off. Have them make 1/4 turns to the left and right (left, right, left, right, repeat) Watch all the steering components and check for any loose parts. Replace as needed.

I have the same problem & about to change transfer case for one off a scrapper (NP242). Will let you know if it cures it. Cost GB£90 & only need new front output oil seal.

Check unit bearings, tie rod ends.. control arm bushings.. OH and your steering stabilizer bushing (axle end).. check your trackbar too.

get a buddy to rock the steering wheel back and forth while you sit under the front of your heep and look and touch all the TREs/etc and look for movement..

check the ball joints.