Thread: rear wheel lockup

This suggests that the drum is loose on the hub - should have three countersunk screws to hold it hard against the hub (often missing) - and that when tightening the wheel nuts, the movement inwards of the drum is either bringing the drum into contact with the backing plate (or something is between the drum and the backing plate) or the drum and brake shoes are grooved, and the grooves do not line up when the drum moves in. This last would be indicated if backing off the adjusters frees the drum.

If the drum is hitting the backing plate, you need to determine why it is. Likely possibilities include a bent backing plate or the drum or the mating surface on the hub damaged, or even just some foreign material stopping it from sitting straight. There is not much clearance.

There are some other possibilities, if for example, you have just fitted new shoes, these may be too wide and touching the drum when it pulls in.

John