In GM 4T80-E units, the OE actuator feed limit (AFL) valve routes regulated line pressure to the pressure control and shift solenoids. AFL pressure feeds the pressure control solenoid, which regulates the outgoing torque signal pressure. AFL pressure is directed to the shift solenoids to oppose spring force and stroke the shift valves. Constant oscillation of this hardened steel valve causes the cast aluminum bore to wear, reducing the AFL oil pressure, which can cause solenoid and ratio codes, clutch/band failure and harsh shifts. Bore wear can also cause the valve to stick in the exhaust position, resulting in 2nd Gear starts and low line pressure. Sonnax AFL valve kit 72854-01K re-establishes the hydraulic integrity of the circuit by eliminating and preventing wear in the AFL circuit.

• Highly wear-resistant aluminum sleeve provides more durability
• Hardcoat anodized aluminum valve combats premature wear and provides better leakage control during thermal expansion
• Valve spools have been lengthened to provide better stability and prevent leakage
• Annular grooves have been added to center the valve and prevent wear from side loading
• A regulating spring has been added to fit into the lengthened valve and set the correct limiting pressure