Symptoms:

  • Slip codes
  • Delayed engagement
  • 1-2-3-4 Clutch burned
  • Shift quality is not load sensitive
  • Harsh shifts
  • Slide shifts
  • Slips & flares

Cause:

Wear in 1-2-3-4 clutch boost valve bore 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.

6T30 (Gen. 1), 6T40 (Gen. 1), 6T45 (Gen. 1), 6T50 (Gen. 1)

Oversized Clutch Boost Valve
Part No. 144740-22


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

The clutch boost valve in GM Gen. 1 6T30/40/45/50 first generation units provides feedback pressure to the 1-2-3-4 clutch regulator valve, balancing the regulator to assist with apply and release of the clutch pack. Pressure control solenoid fluid acts on this valve to precisely control the amount of oil delivered to the balance end of the clutch regulator valve. Wear in the clutch boost valve bore can result in harsh shifts, slipping, burnt clutches, flares and delayed engagement. Reconditioning the bore and installing Sonnax oversized clutch boost valve 144740-22 restores the hydraulic control necessary for trouble-free shifting.

Proper operation of clutch boost valve depends on correct pressure being supplied by shift solenoids. If trouble is found with pressure supply to these solenoids, Sonnax offers oversized solenoid regulator valve 144740-01.

  • Hardcoat anodized aluminum valve combats premature wear
  • Oversized valve engineered to perform to OE specification

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 Gen. 1 6T40, 6T45, 6T50 Valve Body Layout

GM Gen. 1 6T40, 6T45, 6T50 Valve Body Layout
  • 6T30 (Gen. 1), 6T40 (Gen. 1), 6T45 (Gen. 1), 6T50 (Gen. 1) Oversized Clutch Boost Valve 144740-22
  • 6T30 (Gen. 1), 6T40 (Gen. 1), 6T45 (Gen. 1), 6T50 (Gen. 1) Oversized Clutch Boost Valve 144740-22

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.

6T30 (Gen. 1), 6T40 (Gen. 1), 6T45 (Gen. 1), 6T50 (Gen. 1) Oversized Clutch Boost Valve Vacuum Test Locations