Anybody know what material swinging arm spindles are made of? I may need to make a longer one for a 750 kawasaki project Im working on if I can’t find one from another bike. I did think of using En16, thanks
I doubt if it exceeds EN8 in properties, with that or 16 being the most probable. Although it's in a loaded situation that could use a particular spec, the original cross section seems to be made large enough to avoid any particular requirements in high capacity tensile loading.
In other words, looks big enough not to really matter too much. Higher tensile specification would give the option of waisting the centre unused portion of the bolt to save weight if you needed that, not less than the root thread diameter though.
The original manufacture seems to have the bolt head "forged" into shape rather than the overall diameter being machined down with consequent wastage in manufacturing. You'd need to make sure of clean competent radius from shank to head plane to avoid significant stress raiser there.