Sonnax 33886-03K Boost Valve and Sleeve Kit for GM 4T40E 4T45E Transmissions

The Sonnax 33886-03K boost valve kit restores hydraulic integrity and controls line pressure rise in GM 4T40-E and 4T45-E automatic transmissions. This replacement assembly addresses a common wear issue where the boost valve continuously oscillates in the sleeve, leading to hydraulic leakage that can result in either no line rise or unwanted increases in line pressure.

Key Features:

• Replacement boost sleeve delivers oil 360 degrees around the valve, reducing side load and wear
• Sleeve manufactured from highly wear-resistant aluminum for extended durability
• Hard-coat anodized aluminum valve combats premature wear
• Tight tolerances between sleeve and valve maintain an ideal fit that prevents leakage
• Restores proper hydraulic function to the pressure control system

The boost valve assembly is activated by torque signal pressure from the pressure control solenoid and reverse pressure to aid in adjusting line pressure at the pressure regulator valve. When wear occurs in the original equipment, critical oil pressure is allowed to cross-leak between circuits or leak to exhaust, compromising transmission performance. This Sonnax kit provides a durable solution that re-establishes proper pressure control for reliable transmission operation.