Though I haven't had any failures, I don't think those mounts are well engineered. The torque pulses are what we're fighting and that kind of isolating mount is mean for low-amplitude, high frequency vibes. For you engineer-types I mean a rotating radial force vector like that caused by an out of balance prop.

I initially installed one of those Dubro mounts and very quickly wore out the isolators. I went back to the solid, glass-filled type and the airplane seems happier for it. I think that Merle Hyde got it right with his mount. It's designed to dampen shocks in the props plane of rotation - a rotating circumferential force vector.

Sorry...too many big words...my head hurts now.....