September 30, 2005
Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits
Gregg Nader
Symptoms:
- Delayed engagement
- Soft shifts
- Low line pressure
- High line pressure
- Harsh shifts
- No lockup
Cause:
Worn main pressure regulator and/or boost valve bores.Correction:
Sonnax oversized pressure regulator valve and boost valve assembly kit restores proper pressure regulator hydraulic control.Warning:
Required tool kit F-94987-TL11 is no longer in production. Check with your distributor for availability.
450-43LE
Oversized Pressure Regulator & Boost Valve Kit
Part No. 94987-11K
This kit fits '98-later models: Isuzu NPR, GMC Forward Tiltmaster, Chevrolet Forward, Nissan UD and Mitsubishi Fuso Trucks.
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Tooling:
- F-94987-TL11
- VB-FIX
You need this if... View Instructions Find a Distributor
Continuous movement of the pressure regulator valve wears the valve body bore in Aisin AW 450-43LE units. Bore and/or valve wear causes erratic line pressure resulting in delayed engagements, loss of lockup and high or low line pressure, depending on the area and extent of wear.
The boost assembly is designed to increase line pressure in Drive and Reverse. When the sleeve is worn on the inside, boost or EPC fluids can leak to exhaust or cross leak and increase forces on the valve. Leakage to exhaust reduces line rise. Cross-leaks can result in broken clutch drums or cases. Sonnax oversized pressure regulator and boost valve kit 94987-11K restores hydraulic control to these circuits.
- Hardcoat anodized aluminum valves combat premature wear
- Restores proper hydraulic sealing and OE pressure control
- Pressure Regulator Valve
- Boost Valve
- Boost Sleeve
Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.
Aisin AW 450-43LE Valve Body Layout
