Abstract: An apparatus for, and a method of, controlling the torsional damping frequency of a torsional damper using a magneto-rheological fluid disposed between a relatively rotating inertia ring and a surrounding chamber. A coil is continuously wrapped around the chamber and provides at least two slip rings for conducting electricity through the coil from outside the chamber. At least two corresponding wiper contacts electrically connect said slip rings to a source of DC voltage which in turn is controlled by a controller to continuously adjust the damping torsional resistance of the magneto-rheological fluid. A vibration sensor can be associated with the damper and can be signal connected to the controller to continuously adjust the magnetic field through the magneto-rheological fluid to continuously adjust the torsional shear resistance of the fluid, and thereby fine tune damping of the damper.