once you have removed the wheel, chock the front wheels and let off the handbrake. Remove the center cap of the hub (a hammer and srewdriver will do). Undo the big nut, if too tight check the thread to make sure its not left hand thread. Remove the outer bearing and hit the top outer edge of the drum whilst spinning it with a hammer. this should help removal. if it still wont come off you will need to use a lever between the back plate and the drum.
sean mackay, November 2004