First off I apologize if I missed a thread that has already covered this. I could not find one that was specifically related to the 850 sportsman. But anyways, here is my situation. I have a 2010 850 xp w/eps. Today a few buddies and I were out riding. We got into a little mud, nothing to crazy. I got to a point where I had to back up in some mud. The 4WD was engaged and I was not going crazy on the throttle. While backing up, I heard a pop come from the drive line. Looked around the atv the best I could while being in mud. I didn't see anything that looked out of the ordinary. I set it in low and everything was fine. I had 4WD. I had to turn around in a certain area and noticed when I was in reverse, my front diff would not "lock" and I only had the rear wheels spinning. We kept riding and as long as I was going forward, I had 4WD. Never in reverse. When I got home, I changed the front diff fluid and it was dark. It was not milky. The thing is, I just changed the front diff fluid before riding today. Now, if I put the atv on jack stands I am able to confirm that 4wd does engage in reverse and forward. If the atv is on the ground and I make the rear wheels spin, the front diff does not engage in reverse. I always get my 4wd indicator on my display. I'm trying to figure out if I need to remove my front differential and rebuild it? I have no "noises" coming from the front end. I would assume that if something broke internal to the front diff I would have seen something come out when I drained the fluid or I would have heared some form of ratcheting sound while driving it.
Any input would be greatly appreciated.
