I still remember my reaction to my first view of the inner-workings of a
Wankel engine close to 50 years ago.  My immediate thought was "Boy, those
gears in those rotors will probably wear out fast!"

I have never heard/read much about such gear wear, other than being assured
that there was no problem.

During the life of a modified rotary engine, the rotor will make on the order
of one-billion revolutions. That is a lot of potential  metal-to-metal
contact on the teeth of those rotor gears.  Just what does one find when one
tears down an old engine?

I realize that drivetrain gearing, cam gearing, and such on regular  IC
engines outlive a similar number of revolutions (ie My 300Kmile Honda
Accord), but somehow the dynamics of gearing within the rotor of a
high-performance Mazda engine seems to be more metalurgically challenging.

Robin

In theory there is no load. In practice there is some sort of mechanical
vibration going on. Mazda instrumented the gear set and measured
the loads. A simple change in the number of roll pins drastically
reduced the loads and the failure rates.

Paul Lamar