A camshaft phaser controllably varies the phase relationship between a crankshaft and a camshaft in an internal combustion engine. The camshaft phaser includes an input member rotatable by the crankshaft. The input member is connected through a gear drive to an output member which is fixed to the camshaft. A rotational actuator acting on the gear drive unit causes relative rotation between the input member and the output member. A first stop member is rotatable with the input member in a one-to-one relationship. A second stop member is rotatable with the output member in a one-to-one relationship to limit relative angular travel between the input member and the output member. A torque absorption means is provided for limiting the rate at which torque is applied from the rotational actuator to the gear drive unit when the second stop member makes contact with the first stop member.