S (stall issue): With this position the turbine speed is zero and the impeller is rotating; the effectiveness while in the stall stage is minimum amount, close to 50%, meaning that fifty percent of the power coming from the engine is missing by way of friction and dissipated as warmth; https://torqueconverterclutch58136.bloggadores.com/33182997/a-review-of-torque-converter-clutch