A generator rotor shaft includes a shaft body extending through a first axial distance, and being hollow. Spline teeth are formed in an inner bore of the hollow shaft body. The ratio of a distance from one end of the hollow body to a remote axial end of the spline teeth and compared to the overall length of the shaft body is between 0.3 and 0.6. A rotor balance assembly, a generator, and a method of forming a generator rotor shaft are also disclosed and claimed.