Shift Improver Kit 71-77 727 & 904 Trans

The Shift Improver Kit 71-77 727 & 904 Trans is a direct-fit transmission enhancement designed for Mopar enthusiasts running classic Chrysler, Dodge, and Plymouth vehicles equipped with TorqueFlite automatics. Built by B and M Automotive—a trusted name in transmission performance—this kit addresses the soft, delayed shift characteristics common to stock 1971–1977 727 and 904 transmissions. Whether you're restoring a muscle car, upgrading a cruiser, or refining daily-driver responsiveness, this shift kit delivers firmer, faster gear transitions without requiring full transmission removal or major internal surgery.

The Shift Improver Kit works by recalibrating hydraulic pressure curves and shift valve response within your transmission's valve body and governor system. By tightening shift points and increasing apply force during gear changes, the kit eliminates the mushy, rubber-band feel typical of original TorqueFlite programming, resulting in more aggressive 1-2 and 2-3 upshifts and improved throttle response. The modification maintains full streetability and drivability while adding the crisp engagement automotive enthusiasts expect in performance applications. Installation typically involves removing the transmission pan and valve body—a straightforward procedure within reach of any home mechanic with basic tools and a service manual.

This shift kit is ideal for owners seeking affordable transmission tuning without the cost and downtime of a complete rebuild or professional transmission shop work. The compact, lightweight package (0.96 lbs) fits seamlessly into your transmission pan area and is fully compatible with both the 727 (used in full-size and performance vehicles) and 904 (common in mid-size applications) across the 1971–1977 model years. Pair this with quality ATF and a fresh pan gasket for best results and maximum longevity in street, strip, or off-road duty.