No. 45 steel. Stainless steel high-speed running long shafts require steel with high plasticity and high strength. No. 45 steel is the most suitable. It is more economical to use in normalizing or quenching and tempering conditions. The long axis means that the wheelbase is lengthened. The standard axis is relative to the long axis, also called the short axis. The wheelbase is between the midpoints of two adjacent wheels on the same side of the vehicle and perpendicular to the vehicle's longitudinal plane of symmetry. distance.