ALL RIGHT, LET’S GET “THE FAST AND THE FURIOUS” QUOTE OUT OF THE WAY: “YOU ALMOST HAD ME? You never had me; you never had your car! Granny shiftin’, not double clutchin’ like you should … You’re lucky that hundred shot of NOS didn’t blow the welds on the intake!” Aww, yeah. Whether you’re driving an old truck with a non-synchro manual tranny, or are just trying out some racing techniques for smoother shifting, double-clutching might not only be useful, but downright necessary depending on what you’re driving.
When dealing with synchronized or non-synchronized manual transmissions, double-clutching is essentially the same: Push in the clutch pedal; shift into neutral instead of directly into the next gear; release the clutch pedal; engage it once more; then move your gear lever into the next gear.
If used in a racing situation with a synchronized transmission, you’re doing it while blipping the throttle right before downshifting to match the engine rpms to where they should be for the gear you’re going into, which eases drivetrain shock and gives you a smoother gear transition.
With old non-synchro trannies, you also want to try to match the rpms whenever needed to avoid grinding the gears, but some folks will partially engage the clutch for a second to force the transmission to match the engine speed.