An over-running clutch pulley (10) includes a sheave member (20), a hub member (22) located substantially concentrically within the sheave member, and a spring (24). The sheave member preferably includes a sheave input section (26) adapted to engage an input device (12) and a sheave collar section (32) defining a sheave collar surface (34). The hub member preferably includes a hub output section (36) adapted to engage an output device (14) and a hub clutch section (38) defining a hub flange surface (42). The sheave collar surface and the hub flange surface preferably cooperate to substantially define a spring cavity (44) with a cavity axial length (Lc) greater than a static axial length (Ls) of the spring member plus a first predetermined length to avoid substantial contact between the spring member, the sheave member, and the hub member, and less than the static axial length (Ls) of the spring member plus a second predetermined length to avoid substantial buckling of the spring member.