<-=- Club Bevel Heaven -=->

Its a well known fact that the bevel gear failed as Mike won the race. Did we ever find out what caused this?. When you consider that the Desmo set up was designed to reduce the loadings and these motors have competed in endurance racing with much success its a bit odd .Did the crank shims fail and precipitate gear failure?, Incorrect shimming by the factory, or the entrant, poor metal in the gears? Some might say it lasted just right , Its not my view though.Often wondered on this.

I've been told that because of the foot injury that Mike suffered from a race car accident earlier in his career, he didn't like to shift the Duc much, so he overreved the engine during his winning race back in 1978...

HI Peter, I would have expected overreving to bring ring, piston, big end or rod failure, the desmo gear should have been safe to the breathing limits of the motor.

Those gears failed on earlier Ducati racers also, maybe due to lateral movement of the crank but it could be the complete setup of the bevelgears that is stressed to its limits with constant high revving.
The distance between the bearings of the lower bevels isn't really big, so they can get overloaded when revving.If one of the three starts to "go", the rest follows VERY fast due to sideloads on the teeth and completely wrong meshing, increasing load on teeth, messing up meshing etc etc.
Not too long after the fail in that engine, NCR adopted a special support inside on the righthandside to fit the later type of bevels, with some straight gears to get rid of the interaction between the bevels and the movement of the crankshaft.

ducadini