Th400 Modulator

The B and M AUTOMOTIVE TH400 Modulator is an adjustable vacuum modulator engineered for TH350 and TH400 automatic transmissions. This component is essential for drivers and builders who demand precise transmission control and optimal shift quality. As a vacuum-operated regulator, it responds to engine intake manifold vacuum to fine-tune transmission pressure, ensuring smooth gear engagement across varying load conditions and throttle positions.

The adjustable design of this TH400 Modulator allows tuners and mechanics to calibrate transmission pressure mapping for specific engine combinations, driving styles, and performance goals. By regulating hydraulic pressure in relation to vacuum signals, the modulator prevents harsh shifts during acceleration while maintaining firm engagement under load. The compact, lightweight construction (0.29 lbs) integrates seamlessly into existing TH350 and TH400 installations without requiring extensive modifications, making it ideal for both stock restorations and high-performance builds seeking dial-in capability.

This modulator benefits engine builders, transmission rebuilders, and enthusiasts upgrading or fine-tuning Turbo 350 and Turbo 400 transmissions in classic cars, hot rods, and street performance vehicles. Installation is straightforward for experienced mechanics; the unit mounts to the transmission case and connects via vacuum line to the intake manifold. Proper adjustment of the modulator ensures repeatable shift characteristics and helps extend transmission life by optimizing pressure curves. Whether restoring original functionality or optimizing a modified powertrain, the B and M AUTOMOTIVE TH400 Modulator delivers adjustability and reliability for serious transmission work.