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Arrgh! I am going to shoot this thing.


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Well, an oil change at work today turned into an all evening extravaganza. I pulled my ZJ into the shop and put it up on the hoist, to find I had left the oil at home :roll: , so I figured I would take a look at the front end, which had been making a growling noise while low speed turning, and bearing howl high speed. Got it up, threw it in drive, and let the AWD do its thing. Definately coming from the front end. Get the diff cover off to be met with a HUGE amount of silver fluid (which I kinda expected), and a caked up magnet. Took the carrier out, and found a roasted P/S carrier bearing (pitted, and galled bearings). No big deal, just called and got a set of carrier bearings, races and seals. :D Got everything out and off, cleaned it up, drove the new seals in, and pressed on the new bearings with the shims as they were when I took them out. Checked out the rotation of the pinon, felt smooth, and good in rotation. CV shafts felt tight, with no tears in the boots. Unit bearings felt smooth also. Put everything back in, torqued the caps, and RTV'd the cover on while I got the axles back in and brakes put back together. Filled 'er up with lube, and dropped it down. As soon as I backed out, I knew I had made no difference. Still howling at constant speed (like a high pitch bearing drone). And at low speed, when turning it sounds like there is gravel in the front end, and is kind of on-off-on-off. Changes with the speed of the turn. :ack:

 

At this point, I am at a loss. :dunno: Everything on the front end seems good, and the front D/S is a newer CV/DC shaft about 5 months old. I am here to ask if anyone has some ideas... I thought I would have it licked with the carrier bearing (since I DID pull off a bad bearing and you could feel it when I was spinning it in my hand, and had visible wear). :fs1: Is there a break in period for the new carrier bearings? Also, the diff fluid doesn't even seem to come up to the carrier bearings, which seemed weird to me. I would have thought that they would at least be part way under the fluid.

 

Vehicle is a '98 Grand Cherokee ZJ, 4.0L, 42RE, AWD. LP Dana 30 front.

 

Any ideas?

Rob L. :wall:

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Sounds to me like one of the wheel CVs is shot.

 

See, that's what I don't get. That was one of the FIRST things I checked with it acting like it is. They are both pretty tight, with no grinding or freeplay on the ground.

 

Rob L.

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Did you still hear the grind up in the air, or just driving? I have heard many, many rear bearings transmit the noise so that you would swear it is coming from the front. You may have bad rear carrier bearings as well. OR, the pinion bearings you assumed were good really aren't.

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Did you still hear the grind up in the air, or just driving? I have heard many, many rear bearings transmit the noise so that you would swear it is coming from the front. You may have bad rear carrier bearings as well. OR, the pinion bearings you assumed were good really aren't.

 

:agree: I can see how that's entirely possible.

 

Do you have a 242 or 249?

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It made the noise while it was up on the rack also. Definately in the front end. At this point, I am just going to assume that the pinion bearings are bad. :dunno: Ordered up the races and bearings, as well as the crush sleeve I could only get dealer-side. I knew I should have just done the pinion's to begin with, but they didn't have them in stock, and I already had everything apart. :(

 

Oh and its an NP249 :ack:

 

I wish I had a NP242...

 

Rob L.

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Ended up being the pinion I didnt have time to repair. I couldn't get the crush sleeve to crush with the 260 ft lb... So i just tightened it down in increments until I had zero endplay, and about 15 inch pound of rotational force. Think I am good. Its so quiet in there you can hear a pin drop now. :yes:

 

Well, that and the sounds of the rear pinion starting to go out... :ack:

Rob L.

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I'd think it'd be the other way around if anything.

 

Could you explain?

 

I was thinking that the constant binding (although its really not bad, YET) always hammering the bearings might have caused them to fail? :dunno: How could the bearings cause the VC to fail?

 

Rob L.

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I unno. I don't remember what was going on in my head earlier.

 

Is the VC completely seized? Would you be safe to run without a front DS?

 

Its not completely seized... it works, I don't have any unusual wear showing excessive tire scrub, normal turns are ok. The only time it is noticeable is when I have to cut it hard to get into a parking spot. I wouldn't think I would be able to run without a front D/S without having a 242.

 

I am just looking for reasons why the ZJ would have just ate 2 bearing sets since I have owned it(1 front and 1 rear). Maybe its just common is these ZJ axles? :dunno: I know they arent exactly known for strength.

 

Rob L.

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I unno. I don't remember what was going on in my head earlier.

 

Is the VC completely seized? Would you be safe to run without a front DS?

 

Its not completely seized... it works, I don't have any unusual wear showing excessive tire scrub, normal turns are ok. The only time it is noticeable is when I have to cut it hard to get into a parking spot. I wouldn't think I would be able to run without a front D/S without having a 242.

 

I am just looking for reasons why the ZJ would have just ate 2 bearing sets since I have owned it(1 front and 1 rear). Maybe its just common is these ZJ axles? :dunno: I know they arent exactly known for strength.

 

Rob L.

I had the same setup on our 97 GC and had the same issues. I was told by Chrysler in 1998 and 1999 that I shouldn;t be driving it in full time 4wd. The bearings where replaced under our extended warranty twice and when I just drove it in 2WD I didn't have a problem until we sold it in 2002. :dunno:
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...when I just drove it in 2WD...

 

Did you just take out the front shaft or what?

 

Rob L.

They kept the shaft intact, we drove it in 2WD for almost 3 years and no issues. I asked the Dealership why do you advertise "full time 4WD" and then tell us not to use it? Of course I got no response. In 1998 around here it rained almost every day in Spring until June 30 so we used the "full time option" a lot.

 

Do you think maybe there could be an issue with your 4WD disconnect keeping you in 4WD without the light going on?

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...when I just drove it in 2WD...

 

Did you just take out the front shaft or what?

 

Rob L.

They kept the shaft intact, we drove it in 2WD for almost 3 years and no issues. I asked the Dealership why do you advertise "full time 4WD" and then tell us not to use it? Of course I got no response. In 1998 around here it rained almost every day in Spring until June 30 so we used the "full time option" a lot.

 

Do you think maybe there could be an issue with your 4WD disconnect keeping you in 4WD without the light going on?

 

 

Rob(and I) have NP 249 T-cases.... No 4wd disconnect or 2wd mode and no lights come on when the VC locks in. I think you must have had a NP242 T-case. The 249 uses a viscous coupler to lock itself in 4wd. Pretty much a crappy system as the stupid VC wears out and permantly locks itself in 4wd and you are stuck with it.

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...when I just drove it in 2WD...

 

Did you just take out the front shaft or what?

 

Rob L.

They kept the shaft intact, we drove it in 2WD for almost 3 years and no issues. I asked the Dealership why do you advertise "full time 4WD" and then tell us not to use it? Of course I got no response. In 1998 around here it rained almost every day in Spring until June 30 so we used the "full time option" a lot.

 

Do you think maybe there could be an issue with your 4WD disconnect keeping you in 4WD without the light going on?

 

Rob(and I) have NP 249 T-cases.... No 4wd disconnect or 2wd mode and no lights come on when the VC locks in. I think you must have had a NP242 T-case. The 249 uses a viscous coupler to lock itself in 4wd. Pretty much a crappy system as the stupid VC wears out and permantly locks itself in 4wd and you are stuck with it.

You are correct it had the 242, I have read about the "viscous coupler issues" in the 249's, good luck getting it back in shape :cheers:

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The crummy thing is, is that I had no viscous coupler issues until I took the intitave to chage all the fluids. After I got done with the xfer case, started failing. :headpop:

 

Guess thats what I get for trying to take care of it. :roll:

Rob L.

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  • 1 month later...

Got a box in the mail today:

 

 

:D What could it be? :D

 

 

Got my lift in for the ZJ! 2" RE budget boost. Came with shocks, coil spacers, and bumpstops. $250 shipped. Should accompany the new 3.73 Axles well.

 

I got it because since I am going to be doing the axles, and getting a better ratio anyway....

 

Might as well throw a lift on it. :cheers:

Rob L.

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