I am new to ATVs in general and new to Polaris. I recently purchased a 2005 Sportsman 400. Never really noticed anything going on with it until recently. And now that I have snow on the ground i can see and feel it acting up more easily. I have the AWD switch and when I switch it to AWD everything works fine. But when I turn the switch back to 2WD it doesnt fully disengage. So I shift to reverse, run it backwards about 20 feet, and go forward. It then will disengage most of the time. When I really let the rear tires break loose, the front diff will lock in like its in AWD again. I have to shift into reverse again then pull forward a few times before it finally fully disengages. I have read a little about these gearcases but I dont fully understand how they work. Any ideas what could be the issue? Thanks in advance.

Also, what type of fluid is used in the front gearcase? Is it the AGL hub fluid ? I know my owners manual says, but i would like to hear what actual users say.

 

Welcome! Sounds like the armature plate has become magnetized locking the awd in even with the switch off.This happens a lot if the awd switch is left on,but can do it also over a period of time. This was a more common problem on hub activated awd systems,but can happen on the centralized awd systems as well. Especially when you have to use reverse to unlock the awd. Also another problem is the plastic roll cages used in the early models that could crack and do the same thing.Look here on your model under "front housing" and you can see all the parts that are involved. The ONLY fluid to use is Polaris Demand Drive Plus hub fluid and nothing else! AGL is for the transmission (gear case assembly) http://parts.polarisind.com/Browse/Browse.asp
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Thank You very much for all your help. You have answered all my questions very quickly. What, if more, damage can be done if not taken care of asap. I do not use AWD very often.

 

one other thing...where is this armature plate located? Do i need a lot of experience to replace this? I do have a mechanical backround, just never worked on ATVs before.

 

If you looked at the link to the parts breakdown you'll see the front gear case has to be removed and checked out internally. Would help to have a manual on the step by step. OPT

 

Quick question before I start pulling this thing apart. According to the service manual, they say pull off the right wheel. Thats looking from the front correct? Technically it would be the left.

 

Pull the left side drive shaft(facing the front of the machine) remove the 4 bolts on the gear case and remove from the left(wiggle out the front diff from the prop shaft and right drive shaft) and pull the diff out. May take a little wiggling and cussing to do it. Once inside check the roll cage(for any cracking/damage) along with the armature plate for excessive wear. Has an updated roll cage and armature plate number,but think roll cage is still plastic. Others have posted about using John Deere aluminum roll cages instead of oem. Item #8 roll cage, #28 armature plate. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse
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So i pulled the wrong wheel off. Left side facing front of atv, which would be the right side sitting on the machine. I'll switch to the other side. I was fighting getting the lower ball joint off. Hopefully the other side comes off easier. I thought it seemed funny to come out the left side, with the oil tank on that side. So I should be able to push the strut up and work the axle out correct

 

Another update. Im fighting with getting the axle out of the housing. I've about pulled the atv off its stands a couple times, and I cannot get it loose. If anyone has any tips/tricks it would be appreciated. I also dont know if I should just pull the other axle out the same way.

 

That's actually what I did in most cases then I only had to get the prop shaft out,then remove the front diff. Sometimes the manuals instructions tell you to take off too many parts to repair something,other times the instructions are vague or do go far enough in instructions. Plus air chisels work wonders on frozen parts. OPT