Top Fuel Dragsters and Funny Cars have just one “speed”, or gear. There is no transmission, just a clutch in front of the driveshaft that drives the rear wheels. It is direct drive. Imagine your street car, with a manual transmission, was only one speed. That’s what is happening here. In a previous video the gang from Clay Millican Racing showed you the inner workings and info on the clutch itself, which nobody usually shows, and here is how that clutch is applied.
The clutch has a base pressure, which is the amount of engagement that the clutch has when you let your foot off the clutch pedal. With a top fuel car there is very little clutch being applied when you let your foot off the clutch pedal. The clutch doesn’t really grab until you start raising the rpm. Once the rpm comes up the car will start to really move. But it is still slipping the clutch. In order to control the actual “lockup” of the clutch there is a series of timers and solenoids which control air going to the clutch mechanism. By making changes to the settings on the timers, and the amount of airflow, they can adjust when the clutch comes in and how hard all along the race track.
Watch and you’ll get it.