Abstract: The invention provides a flexible folding door adopted to be attached to an existing door jamb comprising a plurality of mini slats. A subplurality of mini slats are bounded on a forward end by a clip to establish a non-folding bound panel segment of the door. A second subplurality of mini slats establish the folding panel seam segments of the door. There is a dual caster assembly and a plurality of single caster assemblies attached to the top of the folding door. The caster assembly consists of at least two low friction wheels mounted on a U-shaped frame having depending legs, each depending leg having a low friction sleeve, the distal portion of each leg is attached perpendicularly to a ring. A stem is adapted to be seated through the ring and through an aperture in the clip and the top of the stem has a cap that overhangs the ring. A retaining pin secures the stem within the ring and thereby attaches the assembly to the clip and the folding door.

Abstract: A counterbalance spring adjustment mechanism, particularly adapted for a rollup type upward-acting door which is supported between spaced apart wall brackets on a rotatable shaft. One end of the torsion spring is connected to a hub including a tubular hub member and a circumferential radially extending flange. The tubular hub member is disposed in a bore formed in one of the wall brackets and is retained in assembly therewith by a cylindrical collar. The door support shaft is disposed in a self-lubricating polymer bushing which is supported in the tubular hub member.