If making a new shaft you can also consider making it to suit readily available seals if applicable.
4140 falls into alloyed steel and is good stuff, if you’re after light weight you can use this and bore out the inside more to be a bit thinner in the wall thickness.
I’m not sure how these shafts are set up for seals but I would probably consider stainless myself, but don’t outsmart yourself by having a stainless nut made. Stainless on stainless in regards to threads is one of the worst as the threads always bind and lock up.
You can polish the seal area for a good surface and I would probably consider making the thread section a bit longer if possible and making a new steel nut a bit longer so that it holds on more threads.
And then there’s Titanium….
That's a bloody good idea regarding the seals Geoff. I would have blindly gone and made up a new one to suit the NLA seals (which when you think about it is pretty dopey)
Not concerned with weight really. The way I ride it would probably not make the difference between coming last and second last
Mostly concerned with the damn thing not leaking.
All other comments taken on board. Have you got a lathe and what are you up to for the next few months
Someone said you were just bumming around the house with nothing to do
I will post up a few pics on the week-end so you can see the set up and so people know what I'm on about.
I think I will leave the Titanium to Ji