My son has a Raptor 80. There is a large nut on the rear axel, on the brake side. This nut is just "floating on the axel. There are threads on the axel that run into the brake cover. If I tighten this nut against the brake cover it butts up to a rubber seal. It looks to me like the nut was not installed properly. Possibly put on backwards as the taper goes toward the wheel. Any suggestions?? I hope I explained it well enough. I posted this under 'Yamaha" also.