In GM Gen. 2 10L60, 10L80, 10L90 and Allison 10L1000 transmissions, the TCC regulator valve controls the application and release of the torque converter. The boost valve and sleeve assembly receives signal fluid that forces the valve to shuttle to its regulating position. In this position, the torque converter apply circuit is open to the secondary line and the torque converter release circuit is vented. This moves the converter into lockup state. Once the signal fluid is removed from the circuit, the TCC regulator valve returns to its install position where the torque converter apply circuit is disconnected from the secondary line and the torque converter release circuit is pressurized. This returns the converter to its released state.

Bore wear around the TCC regulator valve can negatively affect torque converter lockup. Bore wear around the valve reduces converter apply flow, converter release flow and cooler flow. Boost sleeve wear results in signal fluid loss and prevents the torque converter lockup.

Reconditioning the bore and installing Sonnax oversized TCC regulator and boost valve kit 105740-17K corrects the lockup issues along with restoring the proper hydraulic integrity of the circuit.

• Hardcoat anodized aluminum valve combats premature wear
• Highly wear-resistant valve sleeve increases life of part
• Oversized valve maintains OE functions and pressures