Vehicles with GM 8L45 and 8L90 transmissions may exhibit high or low line pressure that results in harsh shifts, burnt clutches, loss of cooler and lube flow and overheating of the transmission and converter. These problems may be caused by wear of the pressure regulator bore at the VFS signal port area and/or at the shuttle valve sleeve. Wear at the inboard port of the pressure regulator bore allows VFS (throttle) signal pressure to leak, preventing proper action of the pressure regulator valve and potentially allowing it to remain in the high line pressure position. Wear of the shuttle sleeve creates a path for balance line pressure at the pressure regulator valve to exhaust, resulting in excessively high line pressure.

Restore hydraulic integrity by reconditioning the bore and installing Sonnax oversized pressure regulator and O-ringed shuttle valve kit 154740-31K. The pressure regulator valve features a lengthened spring pocket spool at the VFS signal port area, which more than doubles the sealing capability to this critical end of the valve. The critical shuttle valve diameter has also been significantly lengthened to provide better sealing and durability of the assembly.

• Hardcoat anodized aluminum valves and highly wear-resistant billet aluminum sleeve combat premature wear
• O-Ringed sleeve provides positive seal against worn castings
• Pressure regulator valve VFS signal spool is 200% longer than OE
• Critical shuttle valve spool made 30% longer than OE for added sealing and durability