Elastomer dampers are tuned to a certain frequency based on the rotating assembly spring/mass system and cylinder pressure. Once you change that system a rubber damper is no longer optimally tuned for that system. Viscous dampers use high viscosity silicone and work over a RPM range. That doesn't mean it's optimally tuned for your particular system. I guarantee most have no idea what the resonant frequency of there rotating system is. Most crankshafts I've seen break due to a improperly tuned damper look just like the OP pictures. 65'
