PDI CAT Crankshaft Damper | C12 and C13Available for: 1994 2007 CAT C12 and C13 Engines Warranty: 1 Year Unlimited Mile Warranty Our viscous torsional damper is a design that consists of a free rotation inertia ring surrounded by a viscous silicone fluid enclosed in a laser welded, sealed housing. When crankshaft torsional vibrations occur, the outer housing of the damper reacts with the crankshaft, twisting as it rotates, while the inertia ring attempts to rotate at a constant speed. This