Control for transmission system utilizing centrifugal clutch

A control system/method for controlling a vehicle drivetrain (10) including an engine (18), a transmission (12) and, a centrifugal clutch (20) for drivingly coupling the engine output (136) to the transmission input shaft (28) during vehicle launch. A system controller (50) issues command output signals (56) for controlling engine speed (ES) on a closed loop basis.