This means that there's a great deal of energy shed in the torque converter, dissipated as heat. In order to boost its performance, companies additional a lock-up clutch to the torque converter. Slippage consumes energy during the coupling phase. Locking the converter shell on the turbine shaft stops this slippage https://torqueconverterclutch60357.rimmablog.com/33131168/torque-converter-clutch-for-dummies