I have a 2005 Sportsman 500 that is stuck in 4WD. I took out the front differential, completely disassembled it, cleaned every piece, inspected every piece (per the service repair manual), reassembled, and put in new fluid. During the "inspection", I found nothing broken (or worn). All springs good, roller cage good, armature plate good, gears good, bearings good,... Only thing I found was a little metal dust stuck to the drain plug (but not much). After all that, I took it out on a test drive, and still stuck in 4WD. I was able to disengage 4WD a couple of times after running in reverse, but it would re-engage again quickly the next time rear tires started spinning. Any suggestions or what I should check or replace next? I really don't want to start randomly replacing parts until the problem is solved because the parts are ridiculously expensive. I'm a huge Polaris fan, but this is testing my loyalty. This ATV has been lightly used the past 10 years, and never abused. Any advice on how to solve this problem is greatly appreciated. If you are not sure, please forward this to a Polaris Tech (if you know one) and ask for there advice. Thank you in advance for your help. Thank you

 

You should have at least replaced the armature plate as they can become magnetized just like the old hub style plates could. This could be the cause of it being stuck in awd mode. Even if power isn't on to the front diff the plate can cause the roller cage to engage. Plus another thing I'd do is to replace the roller cage with an aluminum one. It may not be cracked,but most over a period of time did. Most are around $135 for the roller cage on ebay or you can go with a complete rebuild kit that includes plate,roller cage,seals and bearings.http://www.ebay.com/itm/2004-06-Polaris-Sportsman-400-500-Front-Differential-Rebuild-Kit-ALUMINUM-CAGE-/151630024620?hash=item234dda8fac&vxp=mtr

 

Old Polaris Tech, thank you for the reply. I did inspect the armature plate per the Polaris Service manual, and it checked out OK. Evidently it is supposed to have 2 even round wear rings on one side (of course no broken or bent teeth also). I didn't check it for "magnetism", nor did the Polaris Service manual say anything about that. Is it a common problem for the armature plate to become permanently magnetized? Any way I can verify the permanent magnetism is the problem if I take the part it out? I don't mind spending $70 for a new one, but I would like to verify that is the problem before ordering the part. I assume the dealer won't let me return it if that doesn't solve the problem. Thanks again for your help. Much appreciated.

 

Yes it can become magnetized. Had several in the shop do this before we ever experienced roller cages cracking. I still would replace both and be done with it as many on the forum have experienced.

 

Pull the old armature plate out and wipe it clean, if it sticks to your fridge then replace it :-)
The john Deere armature plate is a lot cheaper than $70 as well!

 

Rooky, I pulled out the old armature plate, cleaned it, but it does not stick to my fridge. I took a picture of it, but evidently I can't post any attachments. I wish I could show it to you guys. I inspected the armature plate, and it has 2 wear rings on it just like the service manual said it should have. I did notice 2 things, but not sure if this is causing the "stuck in 4WD" problem:
1.) There are a couple of intermittent (light) spots on the inner ring. The service manual said that could be a sign of a warped armature plate.
2.) The armature plate is somewhat magnetized to the coil (without power to the coil). I thought there wouldn't be any magnetism unless there is power applied to the coil.

Do you guys have any other suggestions as to what I should check while I have everything apart again? I'm OK with replacing the armature plate if you think that is the problem. What is the JD part number for the armature plate? I know the Polaris part number is 3234101 but its over $70. Thank you again for your help.

Thank you

 

This is all it takes for the armature plate to cause problems,just lightly stick to the coil with power off or from being warped. You can use JD parts,many have had good luck with them,but I still would replace the plastic roller cage with an improved aluminum one.Just my two cents on this.
John Deere Parts.
Roller kit # MIA10666
Cage kit# MIA10667
Seal kit# 10654
Armature plate#MIA10656 Thrust bearing and washer#10663

 

Old Polaris Tech, I got my armature plate from John Deere today (MIA10656). The plate is not the same as the one I took out of my 2005 Sportsman 500. The fingers/locking tabs appear to be the same, but the plate itself has a different shape. The Polaris plate is round on the inside and out, with small oval holes in the center of the ring (color is black). The John Deere MIA10656 plate has large notches on the inner and outer diameter of the plate (color is gray). I'm wondering why the Polaris plate and JD plates are different (I thought they would be identical). I'm OK with using the JD plate, but I'm worried it won't work correctly.

I did some research, and notice at some point in time Polaris changed the Armature plate part number from 3234160 to 3234101. I'm wondering if this part number change is related to the different shape I am seeing with my old Polaris plate versus the new plate I got from JD. Should I use the JD plate, or goto Polaris and get one?

 

Yes the part number did change and the shape did too. You can use it with the other jd parts as some have done. Most didn't have any trouble except mentioned the jd cage was a little longer,but worked after a few engagements. As far as just using the plate,with the oem roller cage,not sure on that one. Imo I wouldn't mismatch parts together. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse The kit I posted earlier shows that the armature plate supplied can be used in place of the original 3234160 also. Lists it at the bottom of the page. http://www.ebay.com/itm/2004-06-Polaris-Sportsman-400-500-Front-Differential-Rebuild-Kit-ALUMINUM-CAGE-/151630024620?hash=item234dda8fac&vxp=mtr&rmvSB=true

 

may help... may not. But my 330 Magnum (2004) started that behavior, and you could run it backwards a bit and it would settle down, only to do it again.

In my own case, I got lucky. A loose ground cable at the battery seemed to be the problem. Tightened that up, and it's been close to a month and no further issues. Check that anway...