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 kit 28821-02K improves transmission performance and durability under high-pressure conditions. The piston can be assembled using only one seal ring for lower friction, two aluminum seal rings or any combination in between.

• 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
• Easy to install, no case modifications required