Transmission Parts GM 4L70-E 4L60-E 4L65-E Valve Body Accumulator Components

Symptoms:

Aluminum pistons wear at the pin bore
Cracked pistons
Delayed engagement
Forward slip
Burnt clutches
Burnt bands

Cause:

Wear at the piston pin bore due to repeated reciprocation and/or cracks in the plastic accumulator piston.

Correction:

Sonnax drop-in pinless Forward accumulator piston kit has dual seals that stabilize and completely seal the piston in the bore.

4L60-E, 4L65-E, 4L70-E

Pinless Forward Accumulator Piston Kit
Part No. 77987-01K

Dual-seal design

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In GM 4L60-E, 4L65-E and 4L70-E units it is common for the plastic Forward accumulator piston to wear or crack. This causes a loss of fluid, resulting in delayed engagement, slips, burnt clutches and/or bands. Repeated reciprocation of the accumulator piston causes the piston pin bore to wear, while fluid loss through the piston pin bore or cracks causes Forward clutch to slip. Sonnax pinless Forward accumulator piston kit 77987-01K eliminates these problems.

Dual seals stabilize and completely seal the bore, providing a tight seal even after thousands of cycles
Pinless design eliminates the possibility of pin leakage, and the additional length stabilizes the piston to prevent piston cocking
Includes steel balls for plugging existing pin bore in valve body
Drop-in Zip Valve™ parts install quickly and easily

Learn More About Zip Valve™ Drop-In Repairs

Contents

Piston
D-Ring
Seal PTFE
Steel balls (2)

Specs

Material: Aluminum

Valve Body Layout

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.