Abstract: A torsion spring assembly for counterbalancing overhead doors which includes an elongated helical torsion spring with coils that are normally spaced apart (when the spring is untensioned), a shaft extending through the spring, and a pair of spring-mounting collars carried by the shaft and provided with slotted neck portions operatively connected to pre-formed hooks at the ends of the spring. One of the collars is fixed against both rotational and axial movement upon the shaft; the other is rotatably mounted upon the shaft; and at least one of the collars is removable from the shaft for field disassembly and reassembly of the parts. The method for constructing the assembly, either during manufacture or in the field, is also disclosed.