The curved ends of the upper tracks are loosely bolted to the tops of the vertical tracks. Ladders or ropes hold up the upper tracks' other ends, roughly level, as we lag-screw the brackets on the curved ends to the door jambs. The supported ends are then loosely bolted to metal hangers lag-screwed to the garage ceiling. Diagonal measurements between the two upper tracks tell us if the tracks are parallel. We make any adjustments needed, then tighten all the fasteners.