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View Full Version : Need HELP - Rear Axle



msvance
11-06-2004, 06:53 PM
this is also posted over on NAGCA but I need as much exposure and help as possible. Thanks in advanced!!


OK, here's the problem - Rear end (Al44) vibration & grinding noise (most noticeable at very very low speed during acc. and dec.), significant "wobble" (edit - in/out, not sure about up/down) on passenger side rear tire. No wobble noticed on drivers side. you can actually see the caliper move in/out.

What I've done -
1. before i noticed the wheel wobble, i adjusted rear pinion angle to spec.
2. after I noticed wheel wobble, I removed wheel & brakes to focus on axle shaft itself - the axle shaft itself wobbles (this eliminated warped rotor, although I do know they are shot). I replaced wheel bearings and carrier bearings. (i also welded the carrier while i was in there)
3. installed axle shafts and still wobble on passenger side and still noises, vibration, etc. on short test drive.
4. ordered new axle shaft thinking it was bent, installed and still wobble. I have not taken it for a drive yet. I have put the vehicle in drive with the rear cover off and not sure if I really notice any wobble of the carrier or not, but I may. Not sure if it is optical illusion or not??
5. I looked at the places where the axle tubes are pressed in to the centersection and there is no sign of fatigue, broken plug welds, stress fractures or anything. If the axle itself was bent or warpped I thought i would notice something there.

Now - what do i do? Thoughts??



Now, to take the story back a little further, I was wheelin' ~6 mo. ago and ripped the upper drivers side rear control arm frame mount off. I patched it up to get home and then built longarms for the rear and installed claytons sub-frame (kept front SA's). I drove for the last ~6mo. like that, and just now put the ZJ in the garage and swapped in a new front axle (hp44, lock-right, 4.10 like the rear), swapped the front 3.5" tera springs to the rear and added 4.5" rubicon exp. springs up front on top of the radius arms which provide ~2" so I netted a lift of ~6.5". In the rear, the only thing I did was adjust the control arms for the proper pinion angle. I also added wheel spacers to the rear which I think made the problem more noticeable than before. Before the recent mods, I had issues, but did not seem as drastic as now. i also blamed part of the issues on the fact that when I installed the longarms I got the pinion angle close, but never fine tuned it because i was planning on swapping in the new axle, supension, etc. Plus, I didn't drive the ZJ a whole lot during that time because it was the same time I bought the Avalanche.

Anyhow, that as much detail as I can give. The only other thing I could think of was a warped housing, but I am not sure how to measure that and like I said, there are no indications of such where the tubes press in to the center section. I'm also irate, becuase I spent money on this thing (bearings and new shaft) which I swore I wouldn't do because I have full intentions of a ford 9"!

HELP!!

OverkillZJ
11-06-2004, 09:36 PM
You did a few things wrong...

1. welded the carrier on an AL44 (read: TURD!)
2. bought a new part for a turd (read: POLSISHED A TURD!)
3. Invested money or effort in a TURD in more than one way, shape, or form.

Really, I'd unload the axle, they're nothing but trouble for most. Some have been lucky, but I don't think you're one of them.

Otherwise I have no technical advice whatsoever, so good luck.

Jim311
11-06-2004, 09:59 PM
New shafts, new carrier bearings, and grinding and noise? You've basically replaced and gutted all the internals of the axle, no? You had this noise before welding the carrier? Are your gears set up properly? Any visible wear/damage on the gears? If not, it sounds to me like you've covered the whole rear end man. I'd start suspecting my transfer case...

msvance
11-06-2004, 11:46 PM
update - i decided to get a little more precise and get out the dial indicator. the new passenger shaft installed had ~0.010" runout. for comparison, the drivers shaft had ~0.010" runout as well! i installed the old shaft and it had ~0.025" runout! Then, I pulled the shaft out of the carrier so it was just riding on the bearing. The new shaft had ~0.025" runout like this and the drivers had ~0.020" runout. The old shaft had 0.040" runout! Sooooo, the new shaft is much better and equal to the drivers side.

Now, why it still visually "wobbled" more, I am not sure. I just put everything back together but don't have any fluid for the rear diff, so I need to wait until tomorrow for a test drive. I'm to the point now, where there really is nothing left to do but drive 'er 'til she dies! :twisted:

overkill - don't remind me about the turd. the intention was to swap the front axle, weld the rear and drive it 'til she blew, then swap the 9" - didn't really know I already had issues. everyone's been there, i thought i just needed bearings, which sucked but was bearable. then i just needed a shaft. it all just adds up. plus, when i swap the 9" i have other plans as well that I don't have the time/funds for. now, at least i have a spare shaft :wink: also, the issues with the al44 compared to fe44 are the lack of lockers (fixed that issue) and spinning tubes. they do have c-clips, but that only makes the matter worse when you break a shaft, doesn't really make it any weaker. i am genuinely conserned about spinning the tubes, but we'll see............

Jim - yep, i pretty much did everything i could. i forgot to mention that the gears look fine. also, the old bearings were scarred but weren't completely destoyed when i replaced them. also, it definitely isn't the tc, because the wobble was at the axle shaft itself.

anymore ideas, let me know, but basically measurements indicate it is as good as the drivers side (assuming that is acceptable) and there really isn't much else i can think of..... If anyone wants to measure the runout on their axle for comparison, let me know :D

Jim311
11-06-2004, 11:49 PM
Just out of curiosity, how much did it run you to replace a shaft? I don't even have any spare shafts for my rear end... if I ever broke one I'd be stuck up shit's creek.

OverkillZJ
11-07-2004, 02:44 AM
I know what it's like to start a repair project, and almost feel like you need to finish it just to feel accomplished. I'm just afraid you're investing more of your time than it's worth :)

msvance
11-07-2004, 10:11 AM
Jim - the shaft ran me $85 shipped to my door.

Overkill - I here ya, but the zj won't be accomplished for a while. when i swap in a rear 9" i also intend to move the tank in the cab, lop off a portion of the rear, build a cage, etc. didn't really have time for all of that. i also would like to spend some time with my wife and the kid before the desert me since I claim i'm building the zj for my wife and as the family cruiser :D

Alaska ZJ
11-07-2004, 01:29 PM
I will bet you a dollar to donuts that the Bearing Journal at the end of the axleshaft is bent. Or the Tube is bent.

msvance
11-07-2004, 07:35 PM
Update - i put everything back together and took it for a spin. it still rattles my teeth from 10-20 mph, acceleration and deceleration. above that speed it rides real smooth! i would think if the tube was bent the vibe would exist at all speeds. i'm just confused and annoyed as hell. i'm beginning to wonder if the wobble has anything to do with the vibration or vice versa. any thoughts??

Alaska - I was thinking along the same lines. do you think it makes sense that it is most noticeable 10-20 mph and not noticeable at all above that speed?

Alaska ZJ
11-07-2004, 09:44 PM
Broken and bent stuff can act REALLY funny....it is REALLY hard for me to give more than a guess over the internet.

Jim311
11-07-2004, 11:20 PM
Shit, if it runs good over 20 MPH... you know what you've got to do!


:lol:

msvance
11-08-2004, 10:08 AM
Jim - yep, Drive 'er 'til she dies!!

However, I really really want to figure out what it is for my own sake. I am beginning to wonder if the rear axle (although there is something obviously wrong there) is actually causing the vibration or if it is something else....... I'll look in to it more, but for now, at least I have my vehicle back together and I can start fine tuning the suspension and can take it on a test trip this weekend :D . I'll post some build-up pics and final resuls later.....

Thanks for the help.........