The Allison transmission control strategy works very well, even allowing torque converter clutch lockup in second gear in some cases. However, in high horsepower applications lockup is sometimes inhibited due to increased torque converter stall speed. Because of this, auxiliary lockup control devices are required to reliably engage the clutch for racing or high performance applications. The BD Allison Lockup Controller gives you control over your torque converter clutch.
The module is equipped with different automatic modes that will automatically engage the TCC when the truck is at high boost based on current gear or a set mile-per-hour. Additionally the module can be setup to use an override switch that will allow TCC operation at any speed as long as it won't stall the engine.
TCC apply is firmer than stock but is cushioned by using PWM ramp up to prevent excessively harsh engagement.Allison transmissions (LML) utilize variable line pressure that adjusts to different engine load to reduce heat buildup in the transmission and improve fuel economy. The problem with this is that it drops line pressure after a shift, causing clutch slippage and failure in higher powered trucks. The BD module is equipped with a pressure controller that boosts line pressure up to 275psi when the engine is over 15psi boost and runs stock pressure under normal conditions to prevent harsh shifting.