A universal grand piano piano action that has adjustable connections between the repetition base, heel, and rest cushion bracket of the piano action to provide a piano action that can be adjusted to fit any grand piano. Other components of the grand piano piano action, such as the jack and flanges, may require specific design and manufacture for each brand of grand piano. Universal grand piano piano action also allows true simultaneous half stroke keyboard design for both the white and sharp keys of a piano and includes the methods for installing simultaneous half stroke keyboard design into a grand piano.