Dumb question .. That's what happened to my secondary all that was left was a small portion of hub left on the jack shaft . But mine was way to light for the job and it just ripped it's guts out , the amazing thing was it didn't even take the undercoating and paint off the underside of the cover nor did it scratch the aluminum engine mounting plate , must be the springs pushing out that makes everything fly out from the main mass of the machine . that said my primary is very light ( 500 sportsman ATV ) and has never gave a hint of any problems .
All the parts look new on the machine and I'm bettin that something didn't get put on or get tightened proper before race day . the big nut would be my guess .. he sploded right off the line no RPM's involved there ..