A transmission clutch control method includes defining a transfer function relating clutch torque to a control signal under transmission operating conditions; determining a target clutch torque for current operating conditions; determining the target control signal from the transfer function to produce target torque at the clutch; correcting clutch torque on the basis of a difference between the target clutch torque and the actual torque at the clutch by adjusting the control signal; calculating actual clutch torque with reference to transmission input torque and transmission output torque; computing a clutch torque error as a difference between calculated clutch torque and the target clutch torque; and repetitively adjusting the transfer function on the basis of the clutch torque error.