Sonnax TH400 Turbo 400 Boost Valve and Sleeve

Precision boost valve and sleeve assembly for the GM TH400 Turbo 400 3L80 heavy-duty automatic transmission. This Sonnax component features precision-machined valve engineered for the TH400's demanding operating environment. Proper servo function is essential for firm band application and reliable shift engagement under high-torque conditions.

Direct replacement for all 1964-1990 TH400 applications in Chevrolet, GMC, Pontiac, Buick, and Oldsmobile vehicles. Whether rebuilding a daily driver or a drag car, this servo component ensures consistent performance every time.