Symptoms:

  • Shift quality is not load sensitive
  • Clutch pressure solenoid codes
  • Burnt clutches
  • Delayed engagement
  • Harsh shifts
  • Slide shifts
  • Slip codes
  • Slips & flares

Cause:

Wear in clutch boost valve bores causes feedback pressure instability, preventing normal shift operation.

Correction:

Recover hydraulic control and renew shift performance by reconditioning the bore and installing Sonnax oversized clutch boost valve kit.

6L45, 6L50, 6L80, 6L90

Oversized Clutch Boost Valve
Part No. 104740-01

Fits any of 3 locations


You need this if... View Instructions Find a Distributor

GM 6L45, 6L50, 6L80 and 6L90 clutch boost valves provide feedback pressure to their respective clutch regulator valves, balancing the regulators to assist with apply and release of the associated clutch. Pressure control solenoid fluid acts on the boost valve to precisely control the amount of oil delivered to the balance end of the clutch regulator valve. Excess wear in boost valve bores can result in harsh shifts, slipping, burnt clutches, flares, codes, and delayed engagement. Reconditioning the bore and installing Sonnax oversized clutch boost valve 104740-01 restores the hydraulic control necessary for trouble-free shifting.
Proper operation of clutch boost valves depends on correct pressure being supplied by shift solenoids. If trouble is found with pressure supply to these solenoids, Sonnax offers oversized AFL valve 104740-12.

  • Hardcoat anodized aluminum valve combats premature wear
  • Annular grooves help center valve in bore to reduce future side-load wear

This valve is packaged individually, but can be used in any of three bore locations:

  • "B" Stamp: 4-5-6 Clutch Boost Valve
  • "F" Stamp: 3-5 Reverse Clutch Boost Valve
  • "K" Stamp: 1-2-3-4 Clutch Boost Valve

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.

GM 6L45, 6L50, 6L80, 6L90 Valve Body Layout

GM 6L45, 6L50, 6L80, 6L90 Valve Body Layout
  • 6L45, 6L50, 6L80, 6L90 Oversized Clutch Boost Valve 104740-01
  • 6L45, 6L50, 6L80, 6L90 Oversized Clutch Boost Valve 104740-01
  • 6L45, 6L50, 6L80, 6L90 Oversized Clutch Boost Valve 104740-01

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected. Valve body casting is stamped with "lettered" locations on the far side of the core; when testing "B" or "F" location, block exhaust hole on far side of core.

  • 6L45, 6L50, 6L80, 6L90 Oversized Clutch Boost Valve Vacuum Test Locations