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Discussion Starter · #1 ·
I bought a nice looking Allis Chalmers 5020 4WD in mid-August with less than 600 hours, and installed a loader. The first day I worked it, I saw the left front wheel catch a few times. I stopped work, took it home, and took it apart. A bearing had disintegrated. The fragments from the hard steel inner race chewed up the spur gears and the housing in a hurry. I thought that it would be useful to document the repair here. It's fairly simple. The most difficult problem is finding parts! The phot here shows the large spur gear that is attached to the stub axle.
 

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Discussion Starter · #2 ·
This photo shows the inside of the housing that hold the spur gears. The debris from the bearing chewed a good bit of the lower mounting bosses away. I'll have to seal them up good to keep from leaking oil.
 

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Discussion Starter · #3 ·
The same bearing that had disintegrated on the left side had a cracked inner race on the right side. This bearing supports the end of the CV joint that drives the pinion gear (which drives the large gear in the post above). If you own one of these tractors, I would recommend removing the final drive units to have a look.
 

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Discussion Starter · #4 · (Edited)
Some of the problem may have been caused by corrosion. At some point, it looks like water had gotten in to both final drive units (left and right) and rusted the bearings. New oil with less than 10 hours on it came out rust colored when I drained it. Most of the bearings either showed signs of overheating or were rusty and rough. I decided to replace all 8 of them (4 each side), along with the seals. Here's what you need for each side:

Oil seal, Allis Chalmers special part 72098775 - $42
King pin housing O-ring, Allis Chalmers part 328146M1 - $12
Bearings available from bearing supply house: 6207, 6305, 6005, 6204 - total about $50.

I forgot to order the cover plate gaskets, so I made my own. I'm not sure of the cost from AGCO.
 

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Discussion Starter · #5 ·
To put everything back together, drove the oil seal into the final drive housing cover. The seal comes with and extra steel/rubber center piece, which doesn't seem to have a purpose - you can see it off to the right. I seated the oil seal with a seal/bearing seating tool, but a block of wood the correct size would work fine.
 

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Discussion Starter · #6 ·
Insert the stub axle through the oil seal. Flip the casting over and install two of the bearings. They fit loosely into the bearing pockets in the casting. All it took to seat them was a light tap with a big dowel rod. I bought a sealed bearing to replace the original small unsealed bearing at the top of the casting. I did this because these bearing were rusted badly in both final drive units.
 

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Discussion Starter · #7 ·
Next, slide the large gear onto the stub axle splines, followed by the inner bearing. I used a pipe nipple to drive the inner race of the bearing (careful not to beat on the bearing balls or outer race) onto the axle shaft.
 

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Discussion Starter · #8 ·
Finish up this assembly with a washer, nut, and cotter pin. The repair manual that I have does not specify a torque, but does caution against backing the nut off to insert the cotter pin. I snugged it down as tight as I could without using a vice, and everything lined up.
 

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Discussion Starter · #9 ·
Now for the tricky/tedious part. There is a two-piece bearing that fits up into the axle housing, which I left on the tractor. This bearing contains 105 4.7 mm bearing balls, that will likely spill all over when you tear everything down. The bearing supply store that I used carried these in stock for $0.13 each, so I bought 20. My dear wife helped me clean the race and the balls, and we secured the balls in the race with a good coating of vaseline.
 

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Discussion Starter · #10 ·
The vaseline was also sticky enough to hold the bearing in place on the axle housing. It goes into the race on the axle housing bearing balls up. Be careful not to pinch the seal on the axle housing. The seals looked to be in good shape, so I did not replace them.

At this point, you also mate the universal joint to the axle, inside of the housing.
 

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Discussion Starter · #11 ·
Place the o-ring (part 3281463M1) into the groove in the kingpin housing. I held it in place with white engine assembly grease. Lift the kingpin housing up and bolt it to the axle housing. I had some help with this, but it's doable by one person. The splined shaft on the universal joint has to pass through the bearing recess in the king pin housing.

Now things got a little funny, and where I might do things differently next time. You have to drive a bearing onto the universal joint, but there isn't a good way to hold the joint steady. I ended up sticking a screw driver up through the lower hole on the housing and driving the inner race with a pipe nipple. Finally got lucky.

Next time, I think I'll work on the shaft with some emory cloth to increase the clearance a little.

Slide the spur gear on to the universal joint shaft and secure it with a snap ring. The snap ring is pretty thin. I had trouble convincing myself that it was seated properly. Sorry, no photo.
 

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Discussion Starter · #12 ·
The last step is to bolt the cover, which holds the spur gears and stub axle, to the kin pin housing. It went on easily. Torque the cover bolts to about 20 ft-lbs and the king pin bolts to 60 ft-lbs. There is a little cutout on the axle hub that allows you to access the bolts.

By the way, I forgot to order gaskets, so I made my own.

I had about 2 hours into the one side that I did today - I didn't have any reason to hurry.
 

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Discussion Starter · #13 ·
Now about the difficulty in getting replacement gears.

The local AGCO dealer found me a new small (pinion, part 72099047) gear for $230. I went ahead and ordered it. It took 2 weeks to get here, I suspect because the local parts man forgot about it for a week. They could not find the larger gear.

I found that Roberts Farm Equipment in Ohio had a salvage Allis 5020 4WD and also a Massey Ferguson 210, which is supposed to be the same tractor. I bought the Massey gears as a set of 2, in nice shape, for $400 delivered. Nice, knowledgeable, hard working folks at Roberts.

It turns out that the Massey gear has a shorter 'snout' than the Allis gear that I need. The Allis parts catalog lists three different gears, but only one with 33 teeth and 23 splines (72099049). So I suspect that the Massey final drives are slightly different. Oddly enough, the king pin housing on my Allis has MF stamped on it - would that stand for Massey Ferguson?

The Massey gear would probably work if I had a spacer machined to fit, but I would rather use the correct gear. So another week's wait for the Allis gear, and then (fingers crossed) the Allis will be ready for winter work. I've already got the snow blower attached.

I now have a spare new pinion gear (part #72099047) that I would be willing to part with at my cost, $230, if anyone needs one. The other alternative is a $50 restock fee from AGCO.
 

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ya can't have to many parts for these 5020's laying around, heck 10 years from now it might be worth a 1000 bucks, lol. parts are really getting hard to find, gonna keep this thread handy in case I need it.......I really hope not though.
 

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Discussion Starter · #15 ·
dt150,

$1,000 may not be far off the mark. Rumor has it that it costs about $1,200 for a custom machined gear. If you have to set up to make one though, might as well make a few more and put them on the shelf in case anyone else needs one.

I was only able to find one 5020 4WD for salvage. I'm sure there are others, and would appreciate any tips. Luckily there seem to be quite a few 2WD 5020's around to pick parts off of.
 

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when your sitting on the seat of the tractor there is a lever just below the seat between your legs that moves up and down. that is the 4x4 lever, I think up is engaged.
 

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I have the manual so if ya have any more questions about what levers do what I can help, but as far this thread I can't be much help....I can try and scan the manual and post it...once I get our good lap top back....no kidding it's taking me 25 min. so far just to try and respond to this post with our old lap top.

These are awsome machines just limited on parts availability...very very limited especialy in 4x4. due to limited funds I have to use my 5020 4x4 or I'd just fix it up and use it only for light work.
 
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