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96 Cherokee front axle problem

minionsram

NAXJA Forum User
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Ok fellers I have been having an issue and decided to break down and see what the good folks at NAXJA has to say. Here is the most detailed way I can put this issue:
Jeep was having a grinding popping type sound with it in 4wd when turning. so I brought it in the garage and jacked it up and put it on 4 jackstands and had the wife "drive" it while I looked at the rotating assebly. When the axles would chatter was when it was turned to the left and it acted like it would of it it had a locker in it. the inside tire would roll with minmal chatter and the outer tire would be almost stopped and would jump. It only does this while in 4wd.
I have checked the front ujoints and the front wheel bearing assembly. I removed the front cover and rolled the diff gears around and looked for any shavings or broken teeth and have none.
I have removed the axle shafts and inspected the splines on it as well. I have no clue what this is and its driving me crazy.
Could the gears backlash if over or under cause a chatter that would act like that?
 
Sure sounds like axle U joints. They can act up and look OK if they are just dry inside the caps, rusted and in the beginning stages of compete failure.

A tip off is to look at the rubber seal around the end caps on the U joint, if it is covered in rust dust, you have likely found your issue. The grease dries out and the roller bearings spit rust dust out around the seal.

Another way to check them is to jam something in the U Joint yoke against the knuckle ( I use a long socket extension) and kind of bounce the tire and look closely at that rubber seal on the U Joint end caps for any kind of movement.

Grab the pinion yoke and yank it side to side, with moderate force. Any sideways movement and your bearings are likely toast. It still sounds like axle U-Joints though.
 
Thanks mud. I have the axle shafts pulled out now. I'll pull the axle joints off and check them. I'll let you know in a few hours what I find.
 
REmember that although eventually axle u-joints will get sloppy when they wear, the first symptom is often that they get very stiff even without visible wear. You can check for this without actually running it. Just jack up the wheel, turn steering to lock, and rotate the wheel by hand. If it binds or stiffness fluctuates as you do this, it's the joint.
 
well guys I removed the U joints to inspect them they were good. With all the agervation I went through to remove them I threw in a new set. Still having a binding issue with the ole jeep. I am at a loss now. The only thing I can think of is the gear set now. Any more ideas?
Also I did try to shake the piss out of the pinion yolk and got no side to side movement but i did get like one to two degree of a turn on it when i rotated it before the gears moved. Think that is too much slop?
 
I doubt gear wear is causing chatter, but then again most anything is possible.

I guess it is possible your carrier bearings are worn and the carrier is lifting a little when in 4X and turning. This can mess with the gear mesh. It usually causes a howl though when driving straight or may even get worse in reverse.

I check the carrier bearings by prying under the carrier and trying to lift it up. If it moves up more than a very little (like thousandths) the bearings are likely on the way out.

Check out the front driveshaft U-joint and the double Cardan joint. They usually don't pop in my experience, the first indicator is usually vibration.
 
I doubt gear wear is causing chatter, but then again most anything is possible.

I guess it is possible your carrier bearings are worn and the carrier is lifting a little when in 4X and turning. This can mess with the gear mesh. It usually causes a howl though when driving straight or may even get worse in reverse.

I check the carrier bearings by prying under the carrier and trying to lift it up. If it moves up more than a very little (like thousandths) the bearings are likely on the way out.

Check out the front driveshaft U-joint and the double Cardan joint. They usually don't pop in my experience, the first indicator is usually vibration.

Ok ill check that in the morning. had to walk away from it for a bit. I had taken some pics of the gears so maybe that will help



 
Hard to tell from the photograph, but your spider gears don't look too healthy, It may just be the perspective and/or the lighting I'm seeing.

I noticed a chunk, chunk, chunk in my front end. The thrust washers for the side gears where really worn in my 88. You might carry a thrust washer down to the local parts place and compare yours to a new one? Mine were really thin, I could tell something wasn't right as soon as I had a thrust washer in my hand, it felt light.
 
well I got out there and checked the carrier and it had no play what so ever when I pryed up on it. I will be checking the front DS joints again but they did look good the last time I looked at them, no play or binding. I think I am going to clean the gears and paint the ring gear and see what the contact patch is looking like now. Ill post some pics of the paint in a bit.
 
well I checked the backlash by spraying some paint on the gears and let it turn for a bit. contact patch looks good. this is getting to be a pain in the .....jeep
photo1_zps0123914f.jpg

photo2_zpsa6de94b5.jpg
 
Could be just the pics, but your spider gears look fishy.
 
ok that is the second vote on my spider gears looking fishy. could they cause a chatter when the vehicle is in 4wd and only when the tires are turned? It dont make any chatter going straight. and can a set of spiders be replaced or reindexed some how? I dont know too awful much about the gears but am trying to figgure it out
 
I don't really know if they can cause a chatter. Usually gears make noise and you follow the sound. Look very closely at the gears, most times they are fairly shinny. They are usually harder near the surface than they are deeper into the metal. If the gears wear enough, the metal starts to look grainy instead of shinny and appears dull or grey.

Color is an indicator, black or blue and you usually have an issue, sometimes tan means you have overheated them in the beginning stages.

Behind the spider gears is a spacer or a bowl shaped washer, this can wear and affect the spider gear mesh. Yours look like they are meshing too near the outer edge, but like I said it could just be the lighting or perspective.

If the spider gears are worn down into the softer inner metal you could get a stick slip situation that resembles chatter. But I'd still bet on a bearing someplace being the cause. I replaced two sets of carrier bearings before I had to replace my spider gear thrust washers, the gears themselves were still in good shape. In the same time period I'd changed a dozen U-joints at various places on my XJ.

Usually what happens to destroy the spider gears is a chipped tooth from someplace (ring gear) gets caught in them and they destroy themselves as they grind it up.

A set of spider gears and thrust washers is easy enough to find and no big deal to swap out. The hardest part might be getting the locking bolt for the cross pin out without snapping it off. It can turn into a giant headache, so I wouldn't swap them out on a guess.
 
ok thamks mud. I am going to pull the carrier and inspect the bearings real good in the morning. It is getting cold as a well diggers ass out in the garage right now. Ill let you know how it looks.
 
Axle u joints will chatter even on jack stands if you are at max turn.

I'd be willing to be the noise is not the diff but the cardan joint in the driveshaft. The extra load from bind on turn will make them chatter if the centering ball is getting worn. Even if it feels good by hand or it doesn't move, you cannot put the torque on it like the drivetrain can. The only way to find it is disassemble the joint.
 
Something else you may want to look at is the slip splines on the front driveshaft. The slip splines on my 96 are a sloppy fit, there is a lot of side play there. It never really caused me any issues, so I've left it. I can picture that if it ever got bad enough it could bind the U-Joint or stress things in a direction they aren't designed for. The slip splines in my 88 are still tight and good, I'll probably swap front driveshafts, between my 88 and my 96, eventually.

Just something to look at, if it isn't the normal culprits, you have to look at other things.

I don't think I'd pull the carrier on a whim, it can be a pain to get back in there. If you decide you have to, don't get the bearing caps mixed up. I usually label mine well and get them back in there the same way they came out. If the shims have a notch or a hole drilled in them, this usually goes at the bottom. You might also call around and line up a case spreader, just in case. Before you try and use a case spreader, talk to someone who knows, you can screw up some stuff using one.

Last thought and I may have my memory wrong and am thinking of another model differential, but I seem to remember a small tub cast under the pinion inside the case. Trash can collect in this tub, bearing flakes, chunks of gear, whatever.

You can make a little pointer out of wire (coathanger or welding rod) bolt it to a cover bolt hole and check the runout on your ring gear.
 
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Axle u joints will chatter even on jack stands if you are at max turn.

I'd be willing to be the noise is not the diff but the cardan joint in the driveshaft. The extra load from bind on turn will make them chatter if the centering ball is getting worn. Even if it feels good by hand or it doesn't move, you cannot put the torque on it like the drivetrain can. The only way to find it is disassemble the joint.
Ill pull it apart and check it. I hope they come apart easier than my axle ujoints do lol.

If it's the driveshaft, then you should be able to test it just by disconnecting it and driving some tight turns with it out. Quicker diagnostic than taking it apart first.
Once I put everything back togeather ill check that if it is still making the noise, Dont know why I didnt think of that.:wierd:
Something else you may want to look at is the slip splines on the front driveshaft. The slip splines on my 96 are a sloppy fit, there is a lot of side play there. It never really caused me any issues, so I've left it. I can picture that if it ever got bad enough it could bind the U-Joint or stress things in a direction they aren't designed for. The slip splines in my 88 are still tight and good, I'll probably swap front driveshafts, between my 88 and my 96, eventually.

Just something to look at, if it isn't the normal culprits, you have to look at other things.

I don't think I'd pull the carrier on a whim, it can be a pain to get back in there. If you decide you have to, don't get the bearing caps mixed up. I usually label mine well and get them back in there the same way they came out. If the shims have a notch or a hole drilled in them, this usually goes at the bottom. You might also call around and line up a case spreader, just in case. Before you try and use a case spreader, talk to someone who knows, you can screw up some stuff using one.

Last thought and I may have my memory wrong and am thinking of another model differential, but I seem to remember a small tub cast under the pinion inside the case. Trash can collect in this tub, bearing flakes, chunks of gear, whatever.

You can make a little pointer out of wire (coathanger or welding rod) bolt it to a cover bolt hole and check the runout on your ring gear.
Well by the time I read this I already had the carrier out. I checked the bearings and they have a small amount of scoring on them that you would find on a set that has 211000 miles on them but they have no side play in them and spin nice. They dont have one touch of blueing on them. I am going to clean everything up inspect everything and put it back togeather. THanks for letting me pick your brains fellers
 
This may be way far fetched, but are you the original owner? Does it have a lift and larger tires? What I'm getting at, and like I said, far fetched...I mean out there, but was it possibly regeared in the rear and not the front? In 4wd you would have different ratios which might cause the chatter... :dunno:
 
no lift. actually stock. 3.55 gears on the front and back. still fighting this. i have the car. joint out right now cleaning it.
 
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