September 30, 2005
Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits
Gregg Nader
Symptoms:
- No 4th
- No 5th
- No 6th
- Low clutch oil pressure
- Harsh shifts
- Flare shifts
Cause:
Excess actuator feed limit (AFL) bore wear allows pressure loss that leads to driveability concerns.Correction:
Recover hydraulic control and renew shift performance by reconditioning the bore and installing Sonnax oversized AFL valve.6T51 (Gen. 3 6T40), 6T50 (Gen. 2), 6T50 (Gen. 1), 6T46 (Gen. 3 6T40), 6T45 (Gen. 2), 6T45 (Gen. 1), 6T41 (Gen. 3 6T40), 6T40 (Gen. 2), 6T40 (Gen. 1), 6T35 (Gen. 3 6T40), 6T31 (Gen. 3 6T40), 6T30 (Gen. 2), 6T30 (Gen. 1)
Oversized Actuator Feed Limit Valve
Part No. 144740-01
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Tooling:
- 144740-TL
You need this if... View Instructions Find a Distributor
The function of the actuator feed limit (AFL) valve is to provide regulated pressure to shift solenoids. Wear in the AFL bore causes low clutch pressure and results in transmission slips/harsh shifts. This eventually leads to a loss of 4th through 6th Gears, and finally the loss of transmission function. Reconditioning the bore and installing Sonnax oversized AFL valve 144740-01 restores hydraulic control for revived shift operation in all ranges for 6T30/40/45/50 (Gen. 1 and 2) and 6T35/31/41/46/51 (Gen. 3 6T40) units.
- Hardcoat anodized aluminum valve combats premature wear
- Annular grooves help center valve in bore to reduce future side-load wear
Tool kit 144740-TL can also be used for Sonnax oversized solenoid pressure regulator valve [14474A0-01].
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 6T30/40/45/50 (Gen. 1) Valve Body Layout
GM 6T30/40/45/50 (Gen. 2), 6T40 (Gen. 3) Valve Body Layout
September 18, 2014
GM Gen. 1, 2 & 3 6T30, 6T40, 6T45, 6T50 Series Identification Guide
October 31, 2014
GM 6T30/40/45/50 (Gen. 1) Vacuum Test Guide
May 25, 2017
GM 6T30/40/45/50 (Gen. 2), 6T35/31/41/46/51 (Gen. 3 6T40) Vacuum Test Guide
January 25, 2023
Uncovering the Root Cause of Pressure & Complaints – The Critical Role of Solenoid Modulator & AFL Valves
Maura Stafford
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.
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