Abstract: A method and apparatus for internally damping vibration and impulse within a crankshaft utilizes the mass of high density inserts and an energy absorbing medium. By placing the inserts into bores in the counter balance weights and surrounding the inserts with the energy absorbing medium, the inserts are allowed to "float" within the counter balance weight, achieving a pendulum damping effect as the inertial mass of the insert responds to vibration propagating along the crankshaft in both directions. In one embodiment the energy absorbing medium is solid but flexible material; in another embodiment the energy absorbing medium is viscous fluid. Because counter balance weights are located at different points along the crankshaft, the present invention damps vibration closer to the sources of the vibration than conventional dampers, thus reducing the propagation of vibration throughout the length of the crankshaft.