Sonnax 77987-01K Pinless Forward Accumulator Piston Kit for 4L60E 4L65E 4L70E

The Sonnax 77987-01K is a billet aluminum forward accumulator piston kit designed for 1993 and newer GM 4L60E, 4L65E, 4L70E, 4L75E, and M30 automatic transmissions. Factory plastic forward accumulator pistons commonly wear or crack, causing fluid loss that results in delayed engagement, slips, burnt clutches, and damaged bands.

Key Features:

• Pinless design eliminates the possibility of pin leakage and features additional length to stabilize the piston and prevent cocking
• Dual seals stabilize and completely seal the bore, providing a tight seal even after thousands of cycles
• Constructed from durable aluminum material for long-lasting performance
• Includes steel balls for plugging the existing pin bore in the valve body
• Easy installation that can be performed with just the pan removed during a fluid change without removing the valve body

Kit includes the pinless forward accumulator piston, piston seals, and two steel balls. This upgrade resolves common issues with worn piston pin bores and provides superior sealing performance compared to stock components.