Dayco PB1084SS PowerBond Race Performance Harmonic Balancer Harmonic balancers serve to absorb and reduce harmonic vibrations from the engine as the crankshaft rotates. Excessive harmonic vibrations at high engine speeds can cause accelerated wear and damage to other components. One of the first symptoms of a potential problem with the harmonic balancer is engine vibration. The harmonic balancer absorbs engine vibrations as engine speeds rise. As the harmonic balancer gets old, it can no longer properly absorb the harmonic vibrations, causing the engine to begin shaking excessively. Once the rubber layer in the harmonic balancer dries or wears out, it can cause the entire harmonic balancer to separate and fail completely.