Basics:
Make sure the shoes are centred vertically as well as horizontally. If they are too low down or too high up the drum won't go back on.
Make sure the handbrake cable is backed right off when fitting new drums or shoes or both. If it's holding the shoes out then the drum won't go back on.
Piston should be able to be pushed back into cylinder without undoing bleed screw - fluid will be forced back to reservoir.
Friction adjusters have a decent amount of play designed into them - they are supposed to allow the brakes to move outover, then control the amount by which they return under spring tension - hence why it's best to have the shoes tapped right back before fitting - to allow the adjuster to do it's job.
If the piston comes out of the cylinder with the brakes assembled, then either you have the wrong cylinder / shoes fitted or the drum is excessively worn.
Make sure the shoes are centred vertically as well as horizontally. If they are too low down or too high up the drum won't go back on.
Make sure the handbrake cable is backed right off when fitting new drums or shoes or both. If it's holding the shoes out then the drum won't go back on.
Piston should be able to be pushed back into cylinder without undoing bleed screw - fluid will be forced back to reservoir.
Friction adjusters have a decent amount of play designed into them - they are supposed to allow the brakes to move outover, then control the amount by which they return under spring tension - hence why it's best to have the shoes tapped right back before fitting - to allow the adjuster to do it's job.
If the piston comes out of the cylinder with the brakes assembled, then either you have the wrong cylinder / shoes fitted or the drum is excessively worn.
