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Wheel Bearings turns into my axle rebuild thread

5K views 47 replies 9 participants last post by  Uniblurb 
#1 ·
First a little history...
When I bought my 1st "mechanics spcl." ZJ Ltd W/Up-Country Pkg. it had a "roar/whine".
I had carrier & pinion bearings installed in both axles from a reputable shop across from Lucas Oil Stadium during construction.
That ZJ totaled due to front end collision:mad:.
A week later, my wife finds duplicate ZJ "mechanics spcl." w/o Up-Country Pkg. from same Chrysler Dealer:kiss:.
Get totaled ZJ as parts Jeep from Insurance co:highfive:.
Transfer rebuilt rear axle & U-C Pkg. Along w/a cornucopia of parts from the wreck over the last 5 years.:cheers2:
Rebuild front axle myself:2thumbsup: as the d-30 from parts Jeep was destroyed:rolleyes:.
Buy my wifes 2-wd ZJ & replace bearings in d-35 axle.:tea:

Present day; Since rebuilt d-44a axle started to roar I order outer wheel bearings as they weren't replaced in the initial rebuild & proceed to tear down to install.
All ready this far I decide to remove carrier and clean and inspect rear end.
Discover galled bearings and races, particularly on drivers side, of the rebuilt axle by a reputable shop with a state contract, that I transferred from parts Jeep.:(
order bearing kit from RRP.:cool:
At this point I started taking photos & will post them with-in the next 24 hrs.
I didn't intend for this repair to be a re-build thread but I guess it is now. I have discovered issues with the installation by a reputable...

More to come as I have to close garage & computer & go to work.
 
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#3 ·
Here are the photos of what the shop did wrong and the results:brickwall. All are taken from drivers side components.

1st 2 are the buggered factory shim. It appears the reputable shop beat it into place in the housing:doh:. This diff has 1 large shim each side of carrier, outside the outer bearing races.

The rest are pitted and galled races and buggered bearings.

I have cleaned and closed everything up for the week end as the machine shop I use closed Fri. about the time UPS arrived with the new bearing kit. I'll post more photos as I get them downsized.
 

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#4 ·
The next few photos are of the various parts cleaned and awaiting re-assembly after large p-bearing is removed and new one pressed on. There is also a photo of my custom cut gasket. It's a personal thing, I prefer a gasket to gasket goo & Lube Locker doesn't make one for the 44-a.
 

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#5 ·
Here is the Trac-Lok with new bearings pressed on. If it looks a little frosty that's because I wrapped it up and put it in the freezer overnight to aid in getting the bearings on. I used the inner race from the old bearings as a pressing tool so as not to damage the bearing carriage. Then struck squarely with a dead blow mallet. After that thoroughly dried the carrier with paper shop towels and air.
 

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#6 ·
Reaching a stopping point till Mon. when shop opens I wrapped the case and axle tube ends with shrink wrap.
 

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#7 ·
I did a couple of things today. I installed the pinion races and a new transfer case output seal since the shaft is out and the seal was leaking. The nicks inside the case I must assume came from that reputable shop.
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I also deburred the buggered shim. I know many of you are against reusing factory shims and I'm sure especially one that has been messed up by a prior servicing. I personally have had excellent luck with reusing the factory shims and always check the pattern before I close up and call it good. I will do the same thing here and with the d-44 & my d-30 having large outer shims, they make a good starting point to adjust without messing up the bearings. I was also careful only to debur and not compromise the integrity of the shim.

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#8 ·
Double- check your carrier bearing caps that you don't have spun the bearings inside them. D44a has a habit of doing that, and once the bearings have spun you may as well say bye-bye to the axle housing. Carrier bearing caps don't have enough clamping force, I've seen people take the caps to a machine shop to shave off a couple thousands from the bottom -at your own risk though :D

The bearings and races on my D44a that had around 95k on the odometer looked exactly like yours. The aluminum- case D44 was not exactly a brilliant idea by Jeep, since the housing can't take the forces from the live axle -> housing warps and causes bearing failures. It's a good unit for independent suspension rear wheel drives though.. ie. think about Dodge Viper.
 
#9 ·
At the machine shop now waiting for guys to come back from lunch. Will post photos after I can get them to proper size.
 
#11 ·
I wouldn't place my bets on the bearings surviving for too long. You never know though, so it might be worth a shot if you don't pay too much for the shop.
 
#12 ·
Shop fees including tips were 30.00. To pull & press bearings & take 1/2 a thousandth off the base of the drivers side bearing caps. I'll post the photos in the next couple hrs.
 
#13 ·
After the guys came back from lunch, we removed and pressed the bearing onto the pinion.
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Then we discussed the cap with the spun race. Since my guy John IS a rear end expert we settled on only taking 1/2 a 1000th of the base of the caps in an attempt to grab the race with out creating an ellipse from a circle. taking the full 5000ths that was grooved would have been too much. I fully realize this is a gamble at saving this axle that I am so far into. If it works it will be great, if not I will have to get an 8.8 or another d-44 and rebuild that. I am greatly disappointed at what a professional shop did to this axle due to carelessness.
 

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#14 ·
And now reassembly begins. Pinion installed and pre-load @ 15 in. #s rotating torque as per low side of FSM for new bearings. Preload was sloppy w/slight endplay @ only 5in. #s during disassembly.
 

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#16 ·
Are you sure about the shop only taking off 1/2 thousandth from the cap? The caps look like investment castings and it looks like they took enough off the take the crown off the casting. I also don't see how cutting 1/2 thousandth from the cap is going to repair ten thousandths of wear into the housing and cap (5 thousandths on each side). I was looking as the angled section near the end of the cap and it looks visibly shorter than the uncut cap. I'd think you'd need to cut at least 10 thousandths which is about how much that looks like.

Also, why didn't Jeep cut the ends of the caps in the first place? That seems like a problem waiting to happen. If the mating surfaces aren't flat and similarly shaped they will wear into each other over time and you will lose your bearing crush especially with aluminum.
 
#17 ·
After measuring both caps, Inside the top of the 1/2 circle and the height of both caps, none of the measurements were the same even within the same cap. I have good contact now and with proper torque everything is tight. I can see why the "reputable shop" had to persuade the shim into place. I used a brass rod ie; if your going to beat something into place use a softer material between the beater and the beatee.
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My next post is the gear patterns.
 
#18 ·
Now that I have checked gear patterns I think that "reputable shop" reversed the factory shims.
The 1st 2 photos with yellow paint are with shims oriented as they came apart during tear down.

The 2 with blue/green paint are after I reversed them.
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What do you all think?
 
#20 ·
I've always heard you can crack the aluminum case if your not careful with the case spreader.
I know I will be chastised for this but I don't have the backlash measurement. I have been successful with factory shims and using the gear pattern with marking paint and the guide in the FSM.

1st gear pattern showed I needed less backlash or to increase shim on drivers and decrease on passenger. The passenger side had a larger shim than drivers so by reversing shims I got the more accurate pattern. It appears the guy at the "reputable shop" didn't even use gear paint. It looks like he tore it apart and threw the parts in a bucket, put in the bearings, did pre-load by "feel" as I hear some do, and then slapped it all together.
 
#22 ·
Yes the second pattern is way better. Have the gear paint cleaned up and the axle shafts installed. I'll get a couple photos before I close it up and fill with Lucas 75w-140 + 1 bottle of Mopar Friction Modifier.
 
#23 ·
Problem w/44a is thermal expansion.... Ultimately you need a tad more carrier preload and endcap crush then an Iron pig would have.
That and Dumb_ss's that jack the rear end up by the center section. Ideally the caps should be torqued into place and measured with a bore gauge then the caps clipped for proper crush spec. If you can get the diff and shims in easily without a spreader or heating the case likely you won't have enough carrier preload. Bottom pattern looks good. Make sure to clean everything. Remember the carrier and axle bearings swap spit in operation so if you do carrier bearings and the axle/axle bearing
is going it with take the other out or vice versa. Make sure the diff is clean inside. After bearing failure the debris has a tendency to get trapped by centrifgal force in the diff. and find it's way out later to trash the new bearings. Worse in trac-locs.
Just my $.05 worth after 40 years experience setting up rear ends.
 
#24 ·
Thanks. As my post began I started by setting up to replace the wheel bearings that weren't replaced with original rebuild. So yes those are done as well. I did in fact thoroughly clean the diff housing & axle tubes. Including running shop towels w/broom stick until the towels came out clean. After getting it back together I did my 1st 5 tire rotation since buying these tires 6 weeks ago.

Now I'm off for a test drive.
 
#25 ·
Just came off the freeway. The roar is gone. The diff cover is not too hot to touch but gets uncomfortable to hold my hand on it for very long. Like 115-120 F or hot water from the tap.
 
#28 ·
A little out of sequence but here are the photos after inserting axle shafts and c-clips. The second 1 caused me to wipe each gear tooth again;)
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Tomorrow I will do an oil change before driving to Chicago, just cause it's about that time anyway.
 
#31 ·
Made it w/o problems. Stopped midway to feel diff. and could hold my palm to it for 20 seconds or so. Just like the 1st test drive
 
#32 ·
I made it through a full week of Chicago driving and back to Indy yesterday without any problems. Rear axle is doing great. If work slows down in next week I plan to open it up and check the fluid for specs of metal. Today I get to replace the blower motor as it stopped last week.
 
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