Sonnax 77764-01 Billet Forward Clutch Piston for 4L60 4L60-E 4L65-E 4L70-E Transmissions

The Sonnax 77764-01 billet forward clutch piston is a high-strength replacement for GM 4L60, 4L60-E, 4L65-E, and 4L70-E automatic transmissions. The original equipment cast aluminum forward piston is prone to failure due to rough castings and high stress concentrations. This upgraded billet aluminum piston eliminates breakage concerns through superior material strength and an enhanced design featuring added contours in high-stress areas.

Key Features:

• Manufactured from high-strength billet aluminum for maximum durability
• Enhanced design with strategic contours to reduce stress concentrations
• Direct replacement requiring no machining or modifications
• Compatible with both early and late model transmissions
• Can be used independently or with Sonnax input housing reinforcement sleeve kit 77733-01K
• Must be used in conjunction with an aluminum overrun piston

This piston provides dramatically improved durability and strength compared to the factory cast aluminum component, making it an essential upgrade for high-performance applications or transmissions with aftermarket shift kits and recalibrations.