August 09, 2018
In GM Gen. 2 6T70, 6T75, 6T80 units, AFL valve bore wear results in low pressure at the shift and control solenoid valve assembly. The OE valve has a large reaction area and is highly affected by side loading which wears the valve body bore. As the bore wear increases, oil pressure is reduced to the shift solenoids which causes solenoid and ratio codes. This also results in lower line pressure.
Installing Sonnax actuator feed limit valve kit 124740-33K renews the hydraulic integrity of this circuit, restoring normal shift operation and feel. This drop-in sleeve/valve assembly provides a new and unworn bore for hydraulic sealing of the valve while the sleeve seals off existing moderate bore wear to prevent fluid loss. A new spring to provide correct limit pressure with the sleeve/valve assembly is also provided.
Due to the design changes on the Sonnax sleeve and valve, vacuum testing at the inboard port is not a valid sealing test.