Symptoms:

  • Low line rise in Drive
  • Soft shifts
  • Burnt clutches

Cause:

Wear of the boost valve sleeve allows EPC fluid pressure escape to exhaust.

Correction:

Sonnax boost valve kit has upgraded materials and minimal clearances to prevent wear and restore proper hydraulic control.

6L45, 6L50, 6L80, 6L90

Boost Valve Kit
Part No. 104520-12K

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

Vehicles with listed GM transmissions may exhibit insufficient line rise in drive ranges, soft shifts and/or burnt clutches. These problems may be caused by continuous oscillation of the boost valve within the boost sleeve, creating excessive wear and a path for EPC fluid pressure to leak to exhaust. Sonnax boost valve kit 104520-12K has upgraded materials and minimal clearances to prevent wear and restore proper hydraulic control. The sleeve also has a slightly larger EPC feed orifice to provide quicker throttle response. A new pressure regulator valve outer spring is also included to replace weakened original springs and provides a modest 5 psi increase across the pressure curve.

  • Boost sleeve is manufactured from highly wear-resistant billet aluminum to prevent wear
  • Larger feed orifice provides quicker throttle response
  • Replacement spring provides modest 5psi line pressure increase
  • Valve
  • Sleeve
  • Spring

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 Boost Valve Kit 104520-12K
  • 6L45, 6L50, 6L80, 6L90 Boost Valve Kit 104520-12K

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.

6L45, 6L50, 6L80, 6L90 Boost Valve Kit Vacuum Test Locations