An improved method of scheduling ratio shifting in a vehicle transmission adaptively adjusts the normal shift schedule to avoid shift-related overheating of the torque transmitting devices of the transmission. In normal operation, transmission shifting is scheduled by comparing measured vehicle speed and engine throttle position values with predefined load data. In the background, the transmission control unit determines the cumulative thermal energy stored in the torque transmitting devices. If excessive energy is indicated, the normal shift schedule is modified to allow extended operation in the lower speed ratios. When the cumulative energy indication returns to a normal level, normal shift scheduling is resumed.