Converter Lockup Control

The B and M AUTOMOTIVE Converter Lockup Control (Part #70248) is an electric torque converter lockup controller designed to give drivers precise command over transmission converter engagement on classic and modified GM automatic transmissions. This kit adds electronic management to the torque converter lockup function, enabling tighter lockup control during highway cruising, improved fuel economy, and enhanced engine braking characteristics—critical upgrades for street machines, tow vehicles, and high-performance builds relying on older transmission platforms.

This controller is engineered to work with GM speed sensors and supports a broad range of classic and vintage GM transmissions, including the TH700-R4, TH200-4R, TH350, 4L60, and TH200. The electric lockup management system allows converters to engage and disengage on demand rather than relying on fixed hydraulic thresholds, delivering smoother shifts, reduced transmission heat under load, and measurable improvements in drivability across varying driving conditions. The compact form factor (5.7 x 5.45 x 7.25 inches) and lightweight construction (0.95 lbs) simplify installation into confined engine bays without requiring extensive fabrication.

Buyers pursuing transmission control upgrades on Chevrolet, Pontiac, Buick, and Oldsmobile platforms will find this kit essential for restomods, performance restorations, and daily drivers seeking modern reliability without sacrificing period-correct aesthetics. Whether supporting a carbureted small-block, a fuel-injected LS swap, or a turbocharged buildup, the B and M lockup controller bridges the gap between vintage transmission hardware and modern driving expectations—making it a go-to choice for builders who demand predictable converter behavior and improved thermal management.