GM Powerglide transmissions used for drag racing generate higher line pressure than the OE servo piston can withstand. At pressures over 200 psi, the OE piston can crack, resulting in transmission failure. Sonnax servo piston and cover kit 28821-05K improves transmission performance and durability under high-pressure conditions.

• High-strength billet aluminum piston also features a rounded profile for better stress distribution
• Dual PTFE seals improve sealing, are low-friction and interchangeable with the OE cast aluminum seal ring
• Lightweight, billet aluminum cover replaces heavy, cast-iron OE cover
• Easy to install, no case modifications required