Welcome to the forums. Yeah, what kind of 4-wheeler are you working on? If it's a Fourtrax 300 and you're trying to remove the rear drum, there's an o-ring up under the front edge of the brake drum where it sits on the axle. You usually can't see the o-ring too good. You have to take a tiny screwdriver or pick and dig it out before the drum will pull off. If that's your case, then you'll have to push the drum all the way back on before you can reach under there with something to get it out. Also, no matter what kind of 4-wheeler you're working on, don't forget to back the brakes off, the brake shoes may be holding the drum. If it's not a Fourtrax 300, tell us what kind it is and we will try to help you.