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:

The Sonnax oversized pressure regulator valve and boost valve assembly kit restores proper pressure regulator hydraulic control.

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.


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. The Sonnax oversized PR valve, boost valve and sleeve kit 94987-11K restores hydraulic control to these circuits.

  • Both the Sonnax aluminum boost and pressure regulator valves are hardcoat anodized to reduce 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

Aisin AW 450-43LE Valve Body Layout
  • 450-43LE Oversized Pressure Regulator & Boost Valve Kit 94987-11K
  • 450-43LE Oversized Pressure Regulator & Boost Valve Kit 94987-11K

You need this if...

A vacuum test at the port indicated fails to hold at least 14 in-Hg.

  • 450-43LE Oversized Pressure Regulator & Boost Valve Kit Vacuum Test Locations