An isolator, comprising: a spring (5, 5a, 5b) having a first spring end and a second spring end; a shaft adapter that is mountable to a crankshaft for rotation about an axis, wherein the shaft adapter has a first adapter drive surface (64, 68) that is engageable with the first spring end and a second adapter drive surface (66, 70) that is angularly spaced from the first adapter drive surface (64, 68) by an adapter drive surface spacing and that is engageable with the second spring end; and a pulley that is engageable with an endless drive member and that is rotatable relative to the shaft adapter, wherein the pulley has a first pulley drive surface (82, 86) that is engageable with the first spring end and a second pulley drive surface (84, 88) that is angularly spaced from the first pulley drive surface (82, 86) by a pulley drive surface spacing and that is engageable with the second spring end, wherein torque is transferrable from the shaft adapter to the spring (5, 5a, 5b) through the first spring end, and from the spring (5, 5a, 5b) to the pulley through the second spring end, wherein torque is transferrable from the pulley to the spring (5, 5a, 5b) through the first spring end, and from the spring (5, 5a, 5b) to the shaft adapter through the second spring end, wherein one of the adapter drive surface spacing and the pulley drive surface spacing is larger than the other of the adapter drive surface spacing and the pulley drive surface spacing, wherein, the isolator is configured that when transitioning from torque transfer from the shaft adapter to the pulley to torque transfer from the pulley to the shaft adapter, the second adapter drive surface (66, 70) engages the second spring end at a different time than the first adapter drive surface (64, 68) disengages from the first spring end, and the second pulley drive surface (84, 88) disengages from the second spring end at a different time than the first pulley drive surface (82, 86) engages the first spring end, and wherein when transitioning from torque transfer from the pulley to the shaft adapter to torque transfer from the shaft adapter to the pulley the first adapter drive surface (64, 68) engages the first spring end at a different time than the second adapter drive surface (66, 70) disengages from the second spring end, and the first pulley drive surface (82, 86) disengages from the first spring end at a different time than the second pulley drive surface (84, 88) engages the second spring end, characterized in that the isolator further comprising a friction member (31, 32) that is fixedly connected to one of the pulley and the shaft adapter and is frictionally engageable with the other of the pulley and the shaft adapter. a spring (5, 5a, 5b) having a first spring end and a second spring end; a shaft adapter that is mountable to a crankshaft for rotation about an axis, wherein the shaft adapter has a first adapter drive surface (64, 68) that is engageable with the first spring end and a second adapter drive surface (66, 70) that is angularly spaced from the first adapter drive surface (64, 68) by an adapter drive surface spacing and that is engageable with the second spring end; and a pulley that is engageable with an endless drive member and that is rotatable relative to the shaft adapter, wherein the pulley has a first pulley drive surface (82, 86) that is engageable with the first spring end and a second pulley drive surface (84, 88) that is angularly spaced from the first pulley drive surface (82, 86) by a pulley drive surface spacing and that is engageable with the second spring end, wherein torque is transferrable from the shaft adapter to the spring (5, 5a, 5b) through the first spring end, and from the spring (5, 5a, 5b) to the pulley through the second spring end, wherein torque is transferrable from the pulley to the spring (5, 5a, 5b) through the first spring end, and from the spring (5, 5a, 5b) to the shaft adapter through the second spring end, wherein one of the adapter drive surface spacing and the pulley drive surface spacing is larger than the other of the adapter drive surface spacing and the pulley drive surface spacing, wherein, the isolator is configured that when transitioning from torque transfer from the shaft adapter to the pulley to torque transfer from the pulley to the shaft adapter, the second adapter drive surface (66, 70) engages the second spring end at a different time than the first adapter drive surface (64, 68) disengages from the first spring end, and the second pulley drive surface (84, 88) disengages from the second spring end at a different time than the first pulley drive surface (82, 86) engages the first spring end, and wherein when transitioning from torque transfer from the pulley to the shaft adapter to torque transfer from the shaft adapter to the pulley the first adapter drive surface (64, 68) engages the first spring end at a different time than the second adapter drive surface (66, 70) disengages from the second spring end, and the first pulley drive surface (82, 86) disengages from the first spring end at a different time than the second pulley drive surface (84, 88) engages the second spring end, characterized in that the isolator further comprising a friction member (31, 32) that is fixedly connected to one of the pulley and the shaft adapter and is frictionally engageable with the other of the pulley and the shaft adapter.