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Discussion Starter #1
Looking at rebuilding a front diff for a friend.
Are there any recommended, aftermarket vendors supplying a quality bearing and seal kit?
 

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Discussion Starter #2
My buddy dropped his bike off over the weekend with a pile of parts.
I got the diff pulled and on the bench. The pinion gear was just floating around in there. The roller bearing looks like it exploded. Shrapnel everywhere.
There is supposed to be a bushing pressed into a blind hole in the diff. The bushing was gone. The hole was hogged out.
I took a picture with a different bushing sitting in the hole.
The case is supposed to have a raised boss cast into it around this bushing. The boss was ground down almost flat.
The roller bearing for the pinion is usually a light interference fit. Its now a NO interference fit.
A good machinist could save it but, I'm no machinist and don't know any that work cheaply around here so, it looks like he needs a new diff.
He bought a rebuild kit off ebay. It took a couple weeks to ship from China. Half the parts are wrong. Looks like he gets to return it.
 

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Discussion Starter #3 (Edited)
Just a few weeks back I was getting ready to head to HMT and found a puddle of oil sitting under my 570.
A little investigative work and I found it was coming from the pinion seal on my diff.
I bought a seal kit from the local dealer for $65 Not happy with the price for a few seals but, glad he had it on the shelf! It was just a couple days before I was supposed to leave on our trip.
I put new OEM seals in the diff and had it all ready to go for our trip.
By the time we were loading up to get home, it was leaking again.

Over the weekend I pulled my diff out to take a look.
I noticed some play in the pinion gear so, I'm sure this is why its leaking again so soon.
The pinion is supported by 2 bearings. One roller bearing on the shaft, and one plain bearing/bushing on the snout.
The plain bearing/bushing on mine was worn down pretty badly causing some play.
The roller bearing wasn't too bad but, enough to warrant replacement.

On another note, the u-joints on my driveshaft were loose. I think this has a MAJOR impact on the pinion bearings. The driveshaft is pretty heavy and has 2 u-joints in it.
It has no support on the front end other than the pinion itself.
The pinion has a really cheap bushing on the nose and a thin (9mm) bearing supporting it midway.
Diffs on other polaris machines have a removable pinion cover, with a bearing and seal built into the cover. This design adds the 3rd bearing near the end of the pinion and adds support.
The diff on the 570 (some 400,450's, etx, ranger, etc..) have this "updated" design, which lacks the pinion cover.
I'm not the only one who believes this. I found some posts on this forum from a russian (?) guy saying they make a kit to fix this. See this link. крышка приводного вала переднего редуктора Polaris Sportsman 400 500 570 с 2013 г.

I'm in process of ordering parts to rebuild my diff and change out the u-joints. I don't like buying junk chinese parts and I don't like paying $60 for a couple of seals from an OEM parts source.
On top of that, polaris does not sell the pinion bushing! Its worthless to replace the roller bearing and not the pinion bushing.
I want OEM quality (or better) but I want to save some money.
I've got a bunch of parts ordered up and they are on the way. Once I confirm it all fits, I'll share some info to hopefully help others in the future.
 

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Discussion Starter #4
Driveshaft U-joints replaced yesterday.
I got some SKF u-joints from NAPA. Around $15 each. Part # UJ338. Box is marked made in China. At least its a name brand. These joints have a grease fitting.
338 is a generic PN for the u-joint. If you call around, most any auto parts store should be able to get them for you.
They were a perfect fit.

I removed the old u-joints with a press.
I installed the new ones with a bench vise, hammer, and a socket.
The ears on these yokes aren't too strong. They can be bent fairly easily.
You need to make sure you take your time and drive the bearing caps in straight to prevent that from happening.

Regarding removing the driveshaft from the pinion. I've read where its recommended to use an air hammer with with a roll pin punch. I'm sure that works great.
My air hammer is out of service. O-rings on the trigger need replaced.
On a whim, I decided to try a hammer drill. I have a nice Bosch drill with multiple modes. Drill/ hammer drill/ hammer.
I put a 1/4" masonry bit in the drill and put it in hammer mode. The roll pin literally FLEW out in a matter of seconds.
Before attempting removal, I sprayed it down with PB Blaster.
The initial hit didn't seem to do anything but all of a sudden, it just took off!

The driveshaft yoke was stuck on the pinion. I had a hard time moving it back toward the engine.
At first, I was trying to pry on it and tap on it up near the diff but, that wasn't working too well.
I grabbed a 3' piece of unistrut and placed in on the yoke back near the engine and was able to tap the whole thing back fairly easily.

Once off the pinion, I pulled it forward and twisted it and it came right out between the frame and motor/motor mount.
 

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2019 Polaris Sportsman 570 SP
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That’s some good info! I just rebuilt a 2003 sportsman 600 front diff, luckily I work in a machine shop and our maintenance supervisor was able to match all the bearings and get them through our supplier, so I got them for free. I used the all balls seal kit and it worked great. Hardest bearing to get was the thrust bearing.
Thanks for sharing!
 

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Discussion Starter #7
I got the diff rebuilt over the weekend and went for a test run.
All went well.

Here is what I used. Note, that these parts are for a 570 differential that DOES NOT have a removable pinion cover. This info will apply to some 450's, 400's, and a few others.
My differential is labeled with Model# 1333393

Bearings: 16006
Need 3 of them. 1 for each axle and 1 for the pinion gear.

Seals: 30X75X10TC
Need 1. For the pinion gear

30X42X7TC
Need 2. One for each axle.

Pinion Bushing :08DU06
Need 1. Supports pinion snout.
NOTE!!! I purchased 08DU08. It is 0.500" tall. It protrudes from the bore that holds it. HOWEVER, I believe that 08DU06 is what Hilliard used and what I would recommend you buy. It is only 0.375" tall. It should drive flush with the top of the bore that holds it, unlike what you see in my photos.

I could have easily bought a rebuild kit from All Balls or some other company but, I've never had luck with generic bearings. By sourcing the parts myself, I was able to get quality parts to rebuild 2 differentials at a cost that was about the same a retailer kit with no name bearings.


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Discussion Starter #8
Pinion bearing interchange info:
08TU06
Interchange #08DU06PAPZ 0806 P10
 
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