A pulley assembly having first and second members. The first member is capable of cooperating with a power transmission belt to drive/be driven by the belt. The first member is movable guidingly relative to the second member around a first axis. A coil spring has a length and a circumference and a first portion attached to the first member and a second portion attached to the second member so that a force tending to move the first/second member around the first axis is transmitted through the coil spring to the second/first member. At least one of the first and second members has a groove bounded by a surface into which the respective portion of the coil spring is fit. The respective portion of the coil spring is clamp fit within the groove.