Description
8L45 / 8L90 Pressure Regulator & Shuttle Valve Kit, Sonnax 154740-02K.
Vehicles with a GM 8L45 or 8L90 transmission may exhibit high or low line pressure that results in harsh/soft 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 casting 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 low line pressure position. Wear of the shuttle sleeve due to continous oscillation of the shuttle valve creates a path for balance line pressure at the pressure regulator valve to exhaust, resulting in excessive low line pressure.
- Hardcoat anodized aluminum valves and highly wear-resistant billet aluminum sleeve combat premature wear
- Pressure regulator valve VFS signal spool 200% longer than OE and operates in unworn area of the bore
- Critical shuttle valve spool made 30% longer than OE for added sealing and durability
- Drop-in Zip Valve™ parts install quickly and easily
- Pressure Regulator Valve
- Spring
- Shuttle Valve
- Shuttle Sleeve
Symptoms:
- Low line pressure
- Burnt clutches
- Harsh shifts
- Low cooler flow
- Loss of lube oil
- Overheated transmission & converter
- High line pressure
- Soft shifts
Cause:
Wear of the OE pressure regulator valve casting bore and shuttle valve sleeve due to continuous valve oscillation prevents proper line pressure control.
Correction:
Install the drop-in Sonnax pressure regulator and shuttle valve kit with upgraded materials and increased critical valve-to-bore sealing engagements to restore hydraulic integrity and prevent future wear.
