Most full manual and transbrake valve bodies use what is known as a fixed line pressure system. In a fixed line pressure system, line oil replaces modulator oil at the boost valve and is known as torque signal oil. Because torque signal oil is fed directly to the boost valve in an unregulated state, it results in a fixed line pressure. This fixed line pressure is equal to the maximum pressure value obtainable with a given boost valve diameter and calibrated pressure regulator spring. A fixed line pressure results in maximum pressure related torque capacity at all throttle angles for maximum performance and durability. Torque signal oil pressure usually originates at the case or valve body and must flow to the oil pump and boost valve to be effective. Due to the internal circuit leakage encountered along the way as well oil pressure fluctuations encountered during gear changes, this method is a primitive means of sustaining a steady fixed line pressure. By removing and replacing the OEM boost valve and pressure regulator spring from the system and installing a calibrated high rate pressure regulator spring and bore plug, the internal circuit leaks and pressure fluctuations which occur in the torque signal circuit no longer have a negative effect on line pressure values. This introduces an incredibly stable fixed line pressure value to the operating system.
THIS SPECIALIZED COMPONENT WILL RETROFIT AND IMPROVE ALL TH400 TRANSMISSIONS WITH ANY MAKE AND MODEL TRANSBRAKE OR FULL MANUAL VALVEBODY. FURNISHES A STEADY 200PSI OF LINE PRESSURE.