The K2 clutch control valve provides source pressure for control of clutch (band) apply and release. Responding to TCU and the linear solenoid, the valve establishes control timing of apply and release relative to engine torque. Bore wear causes an overlap or premature exhaust of clutch pressure. Wear at the B1 brake control valve bore affects apply and release rate. Correction: Either circuit can be repaired to restore the intended control oil pressure and eliminate shift complaints, by installing this Sonnax kit.