i recently bought a early 04 sportsman 400 for my wife.it has 800 miles on it,seems clean but has issues.wen I drive around in 4wd o gravel roads so the hubs engage then stop and try backing up the r.front wheel binds up 25% of the time.its def. not the brakes.when I engage I hard in reverse in 4wd up hill then go forward it pulls hard right and doesnt want to roll ,even In neutral. if I get the jack out and raise it up its free.if I run it while on the jack I cant get it to do it.the only hints I have are there were no clamps on the cv boot on that side.it did not appear contaminated so I greased it and clamped it.when I drained the hub fluid I saw I decent amount of silver in the fluid so I took everything apart and cleaned it.i couldn't find anything worn! the hilliard clutch bearings,cage,spring all looked good.i changed the armature plate tightened hub to 11.5 ft lbs changed fluid twice.i cant find anything.i need this machine to be safe for her and we go away in 2 weeks for our annual quad trip.i am stumped!it was also used to plow a driveway.my next thought is maybe the inner strut bearing

 

Worn hub strut seal sleeve face,inner strut pole damage,too much or not enough clearance on the face of the seal sleeve to the inner strut pole can cause problems also. Rare,but a damaged hub it self can cause problems. Stretched garter springs on the roll cage also.Several things that have to be right or the awd can be erratic.

 

thanks 4 answering.i took the hub assembly and strut after work.found a couple more filings but only scoring was on the cv spindle where the outer strut bearing sits.garter spring appears ok.i removed the cam carefully and pulled the rollers out from the middle.the poles seem ok and look flush.i only have a .002 feeler gauge and couldn't fit it under.it feels like a ujoint binding when it happens and only happens in 4wd after switching directions.hasnt happened in 2w so far.is there anything in th diff that can bind up one wheel?

 

If you've eliminated the strut assy,roll cage,armature plate hub,etc as a problem area,then yes a cv joint itself can be damaged internally, causing binding/locking up even if the boot is intact. You'd have to drop the a-arm,pull the strut out enough to flex the drive shaft out of the strut,to check the cv joint out.

 

I pulled the cv joint off the axle and took it apart and cleaned it.i didn't find anything real bad but did notice some dark spots here and there like it was run low on grease.im pretty sure someone was in there before and changed a bearing.i don't know if he took the clutch apart and maybe stretched the spring but I did have to sand the spindle with fine sandpaper to get the bearing to slide off.one other thing I did notice was when I ran it in 4wd at higher speeds on the jack the bars would kick side to side a little kike there was a hard spot.i didn't try that with the wheels off though

 

Kicking side to side on the bars is kinda normal as both wheels don't lock in at the exact same time plus with no weight on the front tires,this is even more noticeable. Plus if you have any tire sealant this can cause vibration and movement. The newer centralized awd helped on this jerking problem,but had their own set of problems on the early models with roll cages cracking.

 

I understand hat how the 4wd clutch activates but not 100% sure how the rollers lock into the hub.do the rollers just reach the ramps on the cam or do they ride to the peaks?

 

Centrifugal force once the armature plated disengages from the roll cage.. The roll cage rollers ramp up enough to lock firmly into the hub. That's why I mentioned checking the garter spring as it can stretch over time or easily damaged and can have an erratic lock in.The rollers don't ride to the very top of the roll cage.

 

so then when I go from forward to reverse in 4wheel the cam reverses direction and switches ramps. if it doesn't switch fast enough the hub gets bound up.i will change that spring 2morrow 2 be safe.it looks fine but I don't know if someone yanked it off before.this problem only seems 2 happen when I change directions in 4wd that kinda makes sense.ive heard stories from people that these hubs sometimes lockup at speeds and throw people off the machine so I get scared my woman will get hurt.i really appreciate u taking time out of your life 2 share your knowledge.

 

I hope these "stories" are myth. Would think that Polaris could be sued for it.