Shift Kit V/B Repair Kit GM TH400/TH425 1965-Up

The Shift Kit V/B Repair Kit GM TH400/TH425 1965-Up from TRANSGO is a professional-grade internal transmission rebuild component designed for restoring shift quality and eliminating valve body wear issues in classic and vintage General Motors automatic transmissions. Built for mechanics and transmission specialists who demand factory-correct performance restoration, this kit addresses the root causes of soft shifts, delayed engagement, and erratic shift timing that develop as these legendary three-speed automatics age.

The TRANSGO shift kit includes precision-engineered seals, springs, check balls, and valve body calibration components that restore OEM pressure regulation and flow dynamics within the transmission's hydraulic control circuit. Over decades of use, original valve bodies develop wear grooves that allow internal fluid bypass, reducing shift firmness and creating slippage between gears. This kit's components are manufactured to exact tolerances and paired with updated valve specifications that eliminate play while maintaining compatibility with stock transmission architecture.

The repair process involves disassembly of the valve body, installation of new seals and components in factory-specified locations, and reassembly—a straightforward procedure for any experienced transmission technician with prior knowledge. Whether you're rebuilding a muscle car, classic truck, or street rod, this repair kit ensures your TH400 or TH425 responds with crisp, consistent shift characteristics.