August 09, 2018
Second generation GM 6T70, 6T75, and 6T80 transmissions may exhibit multiple line pressure and converter-related problems due to excess wear in the main pressure regulator bore. Wear at the balance spool end allows critical fluid loss, resulting in excess line pressure, harsh shifts and overheating due to reduced cooler/converter flow. Wear at the outboard spool robs converter feed pressure and lowers line pressure, resulting in soft shifts and burnt clutches.
Reconditioning the bore and installing Sonnax oversized pressure regulator valve kit 124740-60K will restore hydraulic integrity for proper line pressure control in all ranges.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.