99 Cherokee Hubs Locked

[Raptor660]

I just recently drove my girlfriend's 99 Cherokee 4x4 and noticed that much past 45-50 mph, there was some front end noise. Low and behold, the front hubs are locked (and have been for who knows how long) and won't unlock.

I haven't been underneath it yet, but someone told me that there should be a vacuum solenoid/actuator for the hubs somewhere on the front axle. I haven't been able to find any information about how to test the actuator once I find it.

At first I thought it may be a vacuum leak issue, but I've read a few places that if the vacuum pressure is the issue I should be noticing other related problems like the A/C blowing hot or out of the wrong vents from time to time.

I was wondering if anyone knows if those actuators are the type that push/pull a lever into the axle, and if it's possible to rig the lever so the hubs are permanently unlocked (until I can get a handle on the issue).

Thanks for the help!

 

[54cj3b]

cherokees came with vac actuators on front diff with self locking hubs so
if its got locking hubs it must be a swaped in diff with non vac I had to soak the hub locks on my 3b to break up all the crud around it then used a pair of chanel locks for leverage to turn them found they were worn bad so I replaced them

 

[Bounty__Hunter]

There are no locking hubs or self-locking hubs on a Cherokee, only unit bearings that serve only to hold the wheel to the axle and allow it to spin. Earlier Cherokee's have a vacuum disconnect on the passenger side of the front axle, easily found by following 2 vacuum lines and an electrical circuit from the chassis to the front axle.

What exactly is the Cherokee doing that makes you believe 'the hubs are locked'?

 

[Raptor660]

Okay, this is going to be a stupid question... if there are no hubs to lock, and just the bearings... is the front drive-shaft supposed to spin when it's in 2H?

I was under the impression that the hubs were locked because of 1) the spinning front drive-shaft and 2) excessive road noise from the front end above 45-mph or so. The gas mileage isn't very great either. At first I thought it was the tires, but I rotated them and checked them all out and they appear to be in really good shape.

I looked all around the front axle for the actuator or vacuum lines. The only vacuum line I see is coming off of what looks like some kind of motor mounted on the side of the transfer case (I think). It has a vacuum line going up somewhere.

I happened to find the manual, and it shows two different setups. One setup has one single vacuum motor with what looks like a lever that goes into the axle. The other setup has two separate motors at each end of the axle that look like they're actually built into the axle. It looked like there were cover plates with 4 bolts for each one.

The manual doesn't show any pictures at all of the first setup (just a routing diagram), and the pictures it shows of the second setup with the two separate motors... doesn't look anything like my axle at all.

 

[Raptor660]

I'm starting to like the guy I bought this thing from less and less...

First I find a half-arsed head gasket repair with silicon all over it, every accessory bracket cracked or breaking from being over torqued...

Now it's looking like some parts were removed from the vacuum system for the front axle.

Does anyone happen to know where I can find a correct diagram with component locations online? The manual I have is crap, and it might help to actually know which parts are SUPPOSED to be on there and where.

Thanks guys.

 

[Bounty__Hunter]

The only disconnect on a Cherokee axle is on the passenger side.

 

[Raptor660]

So after a few of my friends took turns making fun of me, it turns out that I'm not an idiot (at least not because of this).

It looks like someone swapped the front axle on my Cherokee, and it almost looks like an axle from an All-Time 4wd vehicle.

Can anyone tell me where I can cross reference the numbers off of this Dana axle and figure out what vehicle it came out of?

Also, I'm currently accepting ideas for large blunt objects I should use on the guy who sold this thing to me... or maybe myself for not noticing the locked-in front end sooner...

 

[Bounty__Hunter]

What makes you, or your friends, think it's a swapped-in axle? Can you describe what is unique about it or post pics?

 

[jps4jeep]

The Factory XJ vac lock was discontinued in 94 or 95. your D30 front, if original, should not have a vac lock. Someone might have installed a warn full floater kit on the front axle, for $800 or what ever it costs, not many people do this mod.

1st question; looking at your front wheels is there a Hub that you can turn in the center?

Second, on the pass side top rear of the axle is there a funky looking square casting with a funkier looking do-dad coming out, or is it just diff and tube?

Question C- did you buy a 79 or 89 cherokee instead of a 99 cherokee? cause those would answer some questions.

 

[Raptor660]

Okay, I think I finally have something figured out... I got some bad info about how the 4wd worked on this model.

There's no vacuum controlled hubs or any of that. It has auto hubs, and everything up front spins even in 2H.

Looks like the front's not locked in at all, so I must have an issue with either the auto hubs or the axle joints.

Anyone have a guess as to which ones? The vibration/noise starts at about 45 MPH or so, doesn't change with more or less power, doesn't change in turns, remains constant. It's pretty loud in the cab and vibrates the dash pretty nicely.

 

[Bounty__Hunter]

There is no such thing as 'auto hubs' in your jeep, your hubs contain the wheel bearings and have no locking/unlocking purpose. Yes your front driveshaft always spins in 2wd because you have no vacuum disconnect or locking hubs to unlock.

I would start by checking the ujoints in the driveshafts, maybe rotate the tires to see if the vibe changes.

 

[Taylor Made Customs]

Wow, that was pure torture. Is it lifted? It's either the front u-joints or the d-shaft.

 

[Raptor660]

Yeah, correction to my last post.. not auto-hubs.. just regular old wheel hub assemblies that always spin. Stupid design... I'm sure glad my front axle and drive-shaft spin all the time... should be great for longevity. Next project will have to be a manual hub conversion.

I thought I was missing something for sure before...I've never seen this kind of setup on a Jeep before. Always something new to learn I guess.

It's bone stock, no lift or anything. I was planning on lifting it as soon as I got it, but then the motor had to be torn apart and blew all my cash.

I'm getting ready to yank the front drive-shaft and see if the noise goes away. Those stupid wheel hub assemblies are like $120 each, so I'm hoping it's just wasted front u-joints.

Thanks for all the help and dealing with my stupidity guys.

 

[Bounty__Hunter]

No problem, everybody has to learn at some point.

Can you describe the noise? If it's a squeal it is commonly the CV joint in the front driveshaft. Depending on miles it wouldn't be a bad idea to have the front driveshaft rebuilt. A bad CV can break the transfer case in half.

 

[Raptor660]

The noise is a kind of rumble/vibration... something I would expect to hear from a lifted truck with like 35" or bigger mud terrains cruising down the freeway. I, of course, just have the stock size BFG all-terrains on there.

So I yanked the front drive-shaft, and not only did the noise not go away, but now I'm noticing it as early as 30-mph. After that, just for the heck of it, I rotated the tires, and this made no difference.

It doesn't look like it has any normal front wheel bearings. Part listings show an entire hub assembly. So now I'm wondering if the hub assemblies are worn (yay) or if it's coming from the axle joints or what. I know the fluid in the front diff is new and full (with the correct friction mod)...

Not sure where to turn next. With those hub assemblies from $80-200 each, I'd rather not guess and just buy those for the heck of it. I was hoping to just buy some cheap wheel bearings and slap them in, but this design is a little more fun I guess.

 

[Raptor660]

Okay, so while I'm asking stupid questions...

I just noticed that for front hub assembly replacements there are two different kinds:

1) For Cast Rotors & 2) For Composite Rotors.

Anyone know what the difference is? Can I tell just by looking at them? (assuming I know what I'm looking at..lol)

 

[xjmarc]

Jack up the front and see if you can move the front wheels. Grab the top of the tire and see if you can make it wobble. If not the unit bearings are prob good. with it jacked up you can turn the tires back and forth a bit and watch the axle u-joints to see if there is any play. Either way they are both fun to replace.

 

[Raptor660]

Thanks xjmarc, I'm going to give both of those a try today. I'm hoping it's the bearings, so after a couple hundred bucks and a couple hours, this fun little nightmare will go away.

 

[Raptor660]

So I ended up replacing both front hub/bearing assemblies. The noise and vibration in the cab went away nicely, but the front end still starts shaking around pretty good between 55-60mph. The shaking can be felt at the steering wheel. I thought maybe the front drive-shaft needed to be back on, and the whole thing was balanced with the front shaft on, so I threw it back on... no difference.

So now I'm wondering if the front drive-shaft u-joints could be bad... they all looked decent when the shaft was off, and it shakes with or without the front drive-shaft off, so I'm thinking it has nothing to do with the shaft.. ???

When the hub assemblies wear pretty bad, does this usually tend to wear anything else out (axle-shaft u-joints, etc) ???

Here's one other thing I'm wondering (feel free to make fun of me)....

Since the hubs are permanent, and the only thing that changes when I shift into 4wd is the transfer case locks up, shouldn't the front end be in sync all the time? By this I mean, when the front end is jacked up and I spin one front wheel, shouldn't the other wheel spin the opposite way? If not, I'm not quite sure how the front diff on this thing works. When I spin either front wheel, it spins the front drive-shaft, but not the other wheel. Is this thing a typical open diff setup, or what??

 

[Taylor Made Customs]

Believe it or not, a friend of mine had been experiencing the same wabbling issue, it turned out to be the motor mounts. Really.