So I think my reared is about to blow up! Please help...

A

Atl-Atl

NAXJA Forum User
Location
Castle Rock
As I'm driving along this morning I hear a really loud pop and can feel it in the vehicle. It felt almost as if something locked up a rear tire for a second but then let go. I thought I was crazy cause I didn't hear any other noises. So I turned the radio off and drove for another ten mins, sure enough it did it again. The weird thing is it drives totally smooth the rest of the time, then it will randomly go boom! and then be back to normal.

It does not seem to be related to hitting the gas or brake but it may be related to larger bumps. Can't quite tell. It almost feels like there is something in the diff like a chunk of metal that randomly gets caught up in the ring and pinion and gets spit out. I guess it's also possible it could be the t case but it feels and sounds like it's coming from the rear end. I have replaced the t case with one I had installed an AA sye into and put ZJ discs on all about 4 months ago so the fluid is fresh and it didn't appear bad when I drained the old stuff. The t case appeared new inside when I pulled it apart and minimal inspection of the diff when I had the cover off looked good.

The kicker is I just moved into a place with underground parking so I no longer have a garage I can work on the Jeep in :( Anybody in Madison willing to lend a hand, I live downtown.

Mike D

Vehicle info 99xj 4.0 aw4 231, HP30 front 29 spline 8.25 rear, 3.55s open at both ends .
 
how are the u-joints? If they are non greasable they could be randomly binding..highly unlikely, but possible. Are you running a front DS in the back w/ your SYE set up? how much lift?
 
spider gear missing teeth?

You're popping the cover and taking a look anyway. DO it at 1AM and you can get away with that in the garage.
 
I think my buddy had a problem like this in his ctd Ram and it did end up being a joint in the rear driveshaft.

I am running a stock front shaft in the rear with RE full leafpacks that sits pretty friggin high for 3.5"s. The shaft is a little on the short side but it doesn't vibe at any speed. The u joints were not new when I put it in but they were in good shape. I don't think they are greaseable. I replaced one front joint with a greasable, I can check that.
 
if it's a stock front shaft it could be somethig in the double cardan. Check it out before it eats the centering yoke and costs you a whole shaft. You can get a rebuild kit at any spicer dealer fr the centering yoke. the u-joints are just 1310's, the centering yoke kit is the only special thing you need. It took me an evening in the basement with a c-clamp to rebuild mine.

It sounds like you need to crawl under there with a small prybar. Pry the yokes against eachother lightly and look for movement. If they look good I'd pull the diff cover and look for bad things laying in the bottom of the housing.
 
Could be the transfer case like you said. I blew one up, something broke in the rear output shaft bearing retainers and whatnot and things got pushed out of alignment, the teeth on the gears/synchros for the shifter got worn down so bad it wouldn't stay in 4wd and barely stayed in 2wd. Chain stretched, too.

Check your ujoints and rearend first though. If it's not those, check the transfer case.
 
kastein said:
Could be the transfer case like you said. I blew one up, something broke in the rear output shaft bearing retainers and whatnot and things got pushed out of alignment, the teeth on the gears/synchros for the shifter got worn down so bad it wouldn't stay in 4wd and barely stayed in 2wd. Chain stretched, too.

Check your ujoints and rearend first though. If it's not those, check the transfer case.
Click to expand...

I blew my puke goat t-case and it sounded like it came from my rear. (ha ha, I said "from my rear") I upgraded to a 242.

if the drive train looks ok, and nothing else is obvious, before removing the diff cover, open the diff filler hole and feel for metal pieces.

BOB
 
I poked around under the Jeep and externally all seems well front and rear. I just installed an Iron Rock double sheer trackbar setup so I thought maybe something had come loose but that's all tight. I drove it again for about 20 mins and it only happened one time but ONE time at a light As i slowed down i heard a faint "tick tick tick" as i slowly rolled. It almost sound like a stick in the spokes of a bike wheel going very slowly. Any ideas here?

It's hard to tell what's going on at the moment because it just snowed/rained so the underside is soaked. It really feels like it's coming from the right rear although that could just be the tire of choice for locking up if the t case, rear shaft or rear diff is binding. I think I will get a magnet and check the rear diff and t case fluids for metal before I drain them.

I am slightly worried about the t case because the shifter doesn't like to sit perfectly in it's place when in 2wd, it tends to scoot up a few mm's. It definitely doesn't come close to popping out but it's not seated perfectly. I adjusted the linkage to the best of my abilities when I installed it maybe that needs to be checked as well.

Sporadic problems suck, I'll take a constant or escalating problem any day over this!!!
 
if it was ticking at wheel speed you need to look at wheel bearings and brakes.

If it was ticking faster than wheel speed it's driveline/diff related.
 
It could have been wheel speed but it was hard to tell because I was going too slow to tell. It could very well be a wheel bearing going bad which would explain why it seems to be coming from the right rear. It is not doing the normal wheel bearing going bad vibes though, seems more like an individual ball has crept out of the bearing. Maybe the bearing case it failing and each time it makes the BANG its a ball popping out. I guess pulling the diff cover and removing the axle shafts to inspect everything is in order. AARRGGHHH why did I move away from a garage!!! I should know better owning a Jeep!!!
 
I often think that buying an old warehouse in the city and then renting out space to work on vehicles might be a great idea, but then things like liability and insurance and such gets in the way.

and then I remember that no one works on things anymore, they just go get another and the dream vanishes.
 
I have a buddy that had similar problems. Driving down the road and you could feel and hear it happen. Just a loud thud you could feel in your seat. His mechanic at the time drove it for 2 days and didn't do it. Then backing out of his garage it grenaded. I don't know the technical terms but a pin was backing out enough that some rotating part in the diff would hit it and knock it back in place. When it did it in rev and it made contact it kicked it the other way and out the diff cover.


Parakeet
 
That would be the cross shaft and the bolt or roll pin (depending on axle) holding it in place.
 
4wdParakeet said:
I have a buddy that had similar problems. Driving down the road and you could feel and hear it happen. Just a loud thud you could feel in your seat. His mechanic at the time drove it for 2 days and didn't do it. Then backing out of his garage it grenaded. I don't know the technical terms but a pin was backing out enough that some rotating part in the diff would hit it and knock it back in place. When it did it in rev and it made contact it kicked it the other way and out the diff cover.


Parakeet
Click to expand...

This makes the most sense to me.
 
My ZJ did this, turned out to be worn out spider gears and retaining pin. You wont be able to feel any metal through the fill hole....as metal sinks. A visual inspection of the gears wont be enough as they dont have to be missing teeth for deflection to happen, you'll have to check for excess play. Just My .02.
 
4wdParakeet said:
I have a buddy that had similar problems. Driving down the road and you could feel and hear it happen. Just a loud thud you could feel in your seat. His mechanic at the time drove it for 2 days and didn't do it. Then backing out of his garage it grenaded. I don't know the technical terms but a pin was backing out enough that some rotating part in the diff would hit it and knock it back in place. When it did it in rev and it made contact it kicked it the other way and out the diff cover.


Parakeet
Click to expand...

The title of this threw me off cause I thought it was about something else...

After the first couple of posts, my guess is the pin that holds the spider gears in has either lost the bolt that keeps it from moving or has broke and one end is back out. If you keep driving it, you will be replacing the ring and pinion because its hitting the pinion with the clunk.

mac 'simple fix' gyvr
 
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