4L80-E, 4L85-E

Heavy Duty Remanufactured Valve Body
Part No. GM030

Fits '04-later units. Smart-Tech® overrun clutch valve kit installed.

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Sonnax heavy duty remanufactured valve body GM030 has been designed with the workhorse vehicle in mind. Featuring the Sonnax patented 34200-40K Smart-Tech overrun clutch valve kit pre-installed, this valve body corrects the issue of insufficient holding power by the overdrive roller clutch, the underlying cause of chronic overdrive roller clutch failure in 4L80-E units.

This heavy duty remanufactured valve body also includes all new solenoids and a new pressure switch assembly. Chronic wear points in the valve body have also been repaired by reaming and installing top-quality oversized Sonnax valves that optimize valve body function and prevent future wear. These updates correct the common symptoms of wrong gear starts, clutch and band failure, solenoid performance codes, 2-3 neutral, TCC apply and release concerns, TCC and other trouble codes, and various shift complaints.

To guarantee the highest level of operational performance, this remanufactured valve body is tested on state-of-the-art equipment to verify that actuator feed limit pressure, clutch pressures, and torque converter pressures meet the necessary requirements for optimum functionality.

  • Smart-Tech overrun clutch valve kit 34200-40K is pre-installed for unrivaled durability
  • All-new solenoids (EPC, Shift A & B, PWM TCC) and new pressure switch assembly correct shift complaints
  • Chronic wear points including AFL, TCC regulator and accumulator control valves are corrected by refurbishing the bore and installing Sonnax oversized valves
  • 3rd and Reverse checkball sleeves are also replaced as the OE wear over time

  • 4L80-E, 4L85-E Heavy Duty Remanufactured Valve Body GM030

GM 4L80-E Valve Body Identification

Part Number Chart

Part NumberDescription
GM026 (Warranty Only)'91-'92 with Screw-In Temp Sensor
GM027'92-'96 Temp Sensor in Wire Harness



Look for two small holes on the upper right side of the valve body. The holes do not appear on '97-later units.

The screw in the temperature sensor is only used in 1991. All later years use the temperature sensor located in the internal wiring harness.

The lube hole moved to the location
indicated by the arrow above.
Have a late-style EPC, which can be identified by the silver canister.