I have a Zen 90 with this style mount. Flew it till the piston ring wore out.
Then put a YS 90 in its place which was lighter , and help move the CG to its correct position.
The mount has never failed. I balance my props and spinner to reduce vibration.
The pictures were taken in 2003. The plane is still flying with the ys 90
Spares
http://www.airborne-models.com/html/...asp?AGroupID=7
Also use this mount on my Icepoint 2 meter pattern plane. Still no failures. YS 140