High Clutch Piston

The Sonnax 28765‑09 High Clutch Piston is a high-performance, purpose-built upgrade for GM Powerglide transmissions, tailored specifically for stock-style drums. Crafted from robust 6061 forged aluminum, this piston offers significantly improved durability compared to fragile cast OEM units, effectively preventing cracking under high hydraulic pressure.

Its reduced thickness is engineered to accommodate seven or eight friction plates, depending on the specific friction/steel stack used, enabling enhanced clutch capacity and improved line control in high-torque applications.

Ideal for performance builds and heavy-duty rebuilds alike, the 28765‑09 delivers precise fitment, superior strength, and consistent clutch engagement—making it a top choice for builders upgrading or refreshing their Powerglide units.