I have an '02 AC 400I 2x4 manual, I love this quad. I bought it used from a dealer in my town. After owning it for about a month, I noticed a little oil on the skid plate in the rear right under where the drive shaft connects to the diff. not much oil, just a little. This leak go progressivly worse until it was leaking a pretty good puddle on the ground when parked. I contacted the dealer, and ordered a new seal for the front of the diff. This weekend I got a chance to put the seal in, after installing it, I rode for about an hour, and not a drop to be seen, however, after leaving it overnight, I noticed a little gear oil on the skid plate just the same as it was initially, is anyone else have problems with the front seal on the diff. If so, how do I fix this, or do I just live with it.

 

It may not be the seal check the surface the seal rides on, it may be the bearing going out.