As it happens I had a damaged Pantah gearbox lying around from a 350 Alazzurra project.
The clutch shaft is very similar (spline and shaft size, 1st gear) except its 3mm longer on the clutch hub side: the 1st gear sprocket is about 2mm wider/longer than the PT shaft.
All the gears of the Pantah box are wider with atmost 1,5mm.
But they all fit the PT gearbox shafts!
So I exchanged all the gears to have Pantah gears on the PT shafts and placed the shafts into the PT cases with PT selector forks and shiftdrum. And it all works!
advantages of the Pantah gears:
– Pantah gearbox has exactly the same gear ratio’s as the PT.
– They are wider (due to pantah having more power and the same box used upto early 750F1 models) so can handle more power. The PT being phenomenally powered means these gears will last a lot longer before they start pitting/biting/wearing.
– They have 3 large dog clutches making gearshifts easier and more reliable. Just like the single cylinder Ducati’s, the dog clutches of the original PT gears will round off (especially 1ste and 3rd gear) resulting in gears jumping out of engagement.
– Pantah gears are more readily available than PT gearboxes, so that makes looking for replacement gears easier.
Pantah gears on the PT shafts