12in C/T Fast-Lap Torque Converter GM TH350/TH400

The 12-inch C/T Fast-Lap Torque Converter for GM TH350/TH400 is a high-performance transmission component engineered for street and strip applications demanding crisp throttle response and reliable engagement. Built by TCI, a recognized leader in transmission internals, this converter addresses the need for quick acceleration off the line while maintaining drivability in everyday conditions. Whether you're upgrading a classic muscle car, street rod, or weekend bracket racer, a properly matched torque converter is critical to transferring engine power efficiently to the transmission without excessive slippage or heat buildup.

This 12-inch C/T (Cruise/Tight) Fast-Lap converter combines two design strategies to optimize performance across RPM ranges. The stall speed is calibrated to allow the engine to build torque before the transmission engages, improving launch characteristics and off-the-line acceleration without bogging. The tight converter ratio reduces slippage once fully locked, minimizing heat generation during sustained driving and improving fuel efficiency and transmission longevity. At 34.24 pounds, the converter's balanced weight distribution supports smooth operation while the precision-machined internals ensure durability under high-load conditions typical of modified GM powertrains.

This converter is compatible with both the legendary TH350 and heavy-duty TH400 transmissions, making it versatile across a wide range of GM applications from first-generation Camaros and Chevelles to trucks and performance sedans. Installers should verify engine displacement and intended use—stall speed selection impacts launch behavior, so matching converter characteristics to your engine's torque curve and vehicle weight ensures optimal performance. Professional installation is recommended to confirm proper fit, balancing, and transmission tuning for maximum reliability and enjoyment on road or track.