Transbrake

In drag racing, a transbrake is a mechanism that selectively places the transmission in a forward and reverse gear simultaneously.

Historically this was done with a modified valvebody and a single solenoid along with some internal transmission modifications, like increasing line pressure, and removing engine braking band and beefing up internal components to withstand the harsh launches, the valvebody and solenoid when activated allows hydraulic fluid to engage both forward and reverse simultaneously when voltage is applied by the driver with a momentary button, on many ECU controlled vehicles, this is usually done with an electronic control solenoid used to send the ECU, and TCM a directive signal.

"Creep" is allowing the transmission to release some of the pressure for the duration of the time the driver holds the Secondary button.

This also requires the use of a modified valve body inside the transmission allowing the pressure to be redirected to two gears instead of one.

The use of a transbrake can cause premature failure of transmission gears due to the pressure applied.