Hi Amram,

Is your Axiome a foam (Herex) version? Mine is a balsa version and suits the mount perfectly. Perhaps the Herex versions are less stiff? Only other thing I can think of is when you are idling, what rpm is this? If it is too low then your engine movement may be causing the mount to start to limit its travel, causing some shock to be passed to the airframe, causing a stuctural resonance. Mine idles at ~1800rpm without any issues. This might be exacerbated in very hot conditions where the rubber stiffness decreases with temperature?

Best wishes

Keith