Of all the strange driving techniques you’ll hear auto enthusiasts rant and rave about, heel-and-toe has to be the most common. In order to engage the gear that will allow optimum acceleration at the exit of the corner, the astute driver will brake and change down gears simultaneously, all while matching the revs of the engine to the road speed.
The seasoned vet can do this in his or her sleep. But for the initiate it’s a fairly complex process that requires timing and precision to pull off. Technique is all-important because heel-and-toe downshifting happens multiple times every lap in a race and can have catastrophic repercussions if not executed properly.
As Jann states, in a racing situation the driver is braking heavily and most of the car’s weight is on its nose, leaving the rear end unloaded. In order to not upset the rear end in this delicate state, the throttle must be blipped while the clutch is depressed to bring the revs up to the appropriate engine speed that the next lowest gear will engage in.
As you probably know, if you are rolling at approximately thirty miles an hour and suddenly shift from third to second (without blipping the throttle), the car will lurch and you will experience what is known as “compression braking,” where the engine’s off-throttle resistance to revving will physically slow the car.
When the car is braking hard, an abrupt downchange can lock the unloaded rear wheels, resulting in a slide or a spin. By revving between gears to compensate for the relative change in engine speeds, you minimize the chances of locking the rear wheels, ensure the ideal acceleration out of the approaching corner and, incidentally, sound like a world-class driver.