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  • Band failure
  • Clutch failure
  • Harsh shifts
  • Solenoid performance codes
  • Wrong gear starts
  • Soft shifts


Actuator feed limit bore wear causes erratic supply pressure to control solenoids.


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

6L45, 6L50, 6L80, 6L90

Oversized AFL Valve
Part No. 104740-12

You need this if... View Instructions

GM 6L45, 6L50, 6L80 and 6L90 units often suffer from shift abnormalities caused by excess wear in the actuator feed limit (AFL) bore. This wear prevents proper regulation of oil pressure supplied to control solenoids, resulting in harsh or soft shifts, solenoid codes, wrong gear starts, and clutch/band failure. Reconditioning the bore and installing Sonnax oversized AFL valve 104740-12 renews the hydraulic integrity of this circuit, restoring normal shift operation and feel.

Proper AFL action depends on correct line pressure supply to AFL valve. If problems are found with line pressure, Sonnax offers oversized pressure regulator and boost valve kit 104520-07K.

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

Required tool kit can also be used to install oversized AFL valve kit 124740-01 in GM 6T70/75 (Gen. 1) and Ford 6F50/55 valve bodies.

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 vbl thumb

August 21, 2013

GM 6L45-6L90 Vacuum Test Guide

Topics: Vacuum Testing Vacuum Test Guides Transmission GM 6L90 Transmission 6L80 Transmission 6L50 Transmission 6L45 Transmission

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  • 104740 12 combo 1
  • 104740 12

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.

  • 104740 12  1