Hydroformed balance shaft

An engine balance shaft for an internal combustion engine, said balance shaft comprising:

• a hollow tube having a first side wall extending between a first end and a second end of said tube and a tube passageway extending longitudinally through said tube between a first end opening and a second end opening;
• a front bearing journal having a first cylindrical wall with a first passageway extending between opposing ends of said first cylindrical wall, said first passageway configured such that at least a first portion of said tube passes through said first passageway;
• a rear bearing journal having a second cylindrical wall with a second passageway extending between opposing ends of said second cylindrical wall, said second passageway configured such that at least said first portion of said tube passes through said second passageway;
• an elongated counterweight configured to be fixedly coupled with said tube;
• said balance shaft includes a tail piece fixedly coupled with said first end of said tube;
• said tail piece enclosing said first end opening of said tube when said tail piece is assembled with said tube;
• said balance shaft including a counterweight frame;
• and
• said counterweight frame being integrally formed with said elongated counterweight, said tail piece, said front bearing journal, and said rear bearing journal;
• wherein after said tube is assembled with said front bearing journal and said rear bearing journal by passing said first portion of said tube through said first and second passageways, and after said tube is assembled with said elongated counterweight, said tube is expanded through a hydroforming process to fixedly couple said front and rear bearing journals on said tube;
• and
• wherein said counterweight frame being fixedly coupled to said first side wall of said tube when said tube is expanded by said hydroforming process, said balance shaft includes a nose piece fixedly coupled with said second end of said tube, and said nose piece enclosing said second end opening of said tube when said nose piece is assembled with said tube.