Solid shift fork shaft

At the end of the day think about it - if the stock helical cut 2nd gears that side load and flex the shift fork and shaft are replaced with the straight cut 2nd gears that do not side load the fork and shaft the stock hollow shift fork shaft has a much lower load on it and it will have a lesser chance of breaking since it's load is now so much lower.

As stated the solid may resist bending 20% better but if bent in cycles it may break faster than a hollow shaft since it has a solid middle - that's why many highly loaded shafts that have cyclic loads are hollow, it's not just to save weight.

Just looked at my 2010 AW cases & tranny on the work bench - the Shift Drum shaft is solid, the Shift Fork shaft is hollow. I looked into this before when I bought my straight cut 2nd gearset but honestly IMHO I see no reason to replace the hollow shaft with a solid shaft if we're running straight cut 2nd gearsets.

Having said that highly boosted stock engines drag racing with a stock helical gearset ? Yes, it needs to be stronger but if you're doing that high boost riding/racing you've got weak spots that will be bigger problems that will surface and when they do you'll be inside the engine and can replace the helical gears with straight cut gears then - and maybe install a new hollow shift fork shaft as a precaution since it's been abused racing with helical gears -

Yes a heavy shift foot or air shifter that's incorrectly adjusted passes a lot of force thru shift shaft ( they break ) and then upstream with pressure on the shift pawls / shift drum and forks that goes way up - but also the side load on those helical gears is something the forks & shaft have to control and fight if the load is not removed by an ignition interrupter or by proper rpm / speed shifting - so on high power bikes with manual shifting and helical gears there is a higher possibility of overloading forks and shaft when racing and completing 4 upshifts in 9-11 seconds with power partially or fully applied - undercutting the dogs, proper air shifter adjustment with ignition cutout and straight cut gears all mitigate the limitations of the stock street bike gearbox, but it's not cheap, 1K for street cut 3K + for a full race tranny from the guys here in Clearwater FL.
After all their careful setup V&H may have decided for them the solid fork shaft was cheap reliability insurance and maybe more accurate shifting under constant Pro level racing conditions. Now they're out of production any solid shaft that's made would have to be the proper hardness and surface smoothness after machining and that is a challenge. May be better to simply replace the hollow OEM shaft with new every third rebuild or 10K miles at the discretion of the builder -

Ok. Wanted to test this because old one is sligthly worn already. I made it from case hardened steel with grinding machine. Diameter is the same than original but it is now same all the way. Left one is original and right the new one. There is small centering bores in both ends for grinding machine.