Sonnax heavy duty remanufactured valve body GM054-HD provides forward sprag protection in GM 4L60/65-E units by applying the overrun clutch in all forward ranges other than 4th Gear. This helps prevent forward sprag failure and provides better forward clutch durability.

Ideal for vehicles with increased horsepower and torque, GM054-HD is built to overcome chronic shift and converter clutch apply complaints. It provides firmer shifts and a moderately increased pressure curve to improve performance, especially in truck and towing applications.

Numerous Sonnax valve upgrades are included to restore hydraulic clearances that lead to shift complaints, clutch distress, converter complaints and codes, solenoid issues and pressure problems. Line pressure rise has been moderately increased to overcome shift complaints, delayed engagements, and to increase holding power to the clutches.

To guarantee the highest level of operational performance, this remanufactured valve body is tested on state-of-the art equipment to verify that solenoid feed, clutch, converter and line pressures match or exceed OE specifications.

• Sonnax components outperform and outlast OE to eliminate chronic shift and converter apply problems
• Firmer shifts under load and moderately increased line pressure improve transmission performance and durability

The valve body includes the following:

• Oversized TCC regulator valve and sleeve, and limit valve spring for firmer TCC application
• O-Ringed bore plugs and abuse plugs
• New accumulator control valve and sleeve with spring
• Oversized AFL lineup
• New Forward accumulator piston and seal
• New pressure switch manifold
• New EPC solenoid
• New TCC PWM solenoid
• New servo cushion spring to help reduce downshift clunk

Included with your purchase:

• Sonnax boost valve assembly with elevated pressure regulator spring, 4L60E-LB2
• New separator plate and gaskets
• Two new accumulator piston springs
• Sonnax EPC harness adapter 34435-01K for ’03-later units