Heel-and-Toe: Efficient Downshifting Technique
Before attempting any kind of modification in your day-to-day driving behavior you should at first find yourself on a racing track or any other similarly controlled environment (other than a public road). The “heel-and-toe” is basically a driving technique which combines braking with gear changing down. This is done usually before approaching a corner in order to maximize your speed while keeping the car's dynamics to a much safer level.
The purpose of the technique is to smoothly match the engine's speed with the wheels' speed. We should also mention (really important, actually) that this only works with cars that have three pedals (ed, manual transmission). Let's first look at how a normal driver would downshift while approaching an intersection. We shall call that driver “James” (according to the US Census Bureau, “James” is the most common male name for people living in the United States):
James is approaching a right-hand corner while in fifth gear at about 50 mph (80 km/h). Since the corner is not wide enough to allow our hero to safely make it around it, James starts braking until the car's speed drops to about 30 mph (50 km/h). The engine's rpm will begin to drop so he has to push the clutch as he enters the corner to prevent stalling. As soon as he thinks about accelerating again, James will realize that he's still in fifth gear, which is totally unsuitable for strong acceleration at such low speeds.
Ergo, he will shift from fifth to third gear, let out the clutch and drive away. The problem with James' line of thought is that by doing what he just did, the car will jolt a little and the clutch and transmission will suffer undue wear-and-tear. The reason for this is that because he shifts from fifth to third, the mechanical lock between the engine and the driving wheels forces the engine revolutions to match the rotational speed of the wheels. In other words, the engine will jump from almost idling (while the clutch was depressed) to the rpm needed for third gear (engine braking).
The solution for James' problem is heel-and-toe shifting. By combining the braking and gear change when approaching a corner instead of performing them as two separate actions you'll be faster AND protect the transmission. When first trying this, it is essential that you're not driving heeled shoes. Running shoes with thin soles are pretty efficient for driving, but there are also specially designed driving boots out there.
Now, as you approach the point of no return (aka “braking point”), cover the brake pedal with your right foot's toe. The brake is the priority between the two pedals you're going to operate with the same leg, so ensure good contact and no risk of foot slip. Apply the brake to a point where it's possible to change down without over-revving. Then rotate your right foot and prepare to press the accelerator with your heel. As fluid and uninterrupted as you can do it, press the clutch with your left foot, increase the engine revs with the heel of your right foot, change down and release the both the clutch and the brake. Take the corner and continue accelerating.
We know it sounds a bit complicated while you're reading this, considering the technique involves both of your feet, your right hand (or left if you're British), all three pedals and the gear lever (your other hand is still in charge of the steering wheel). Remember, practice makes perfect.
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However, one can still downshift for cornering without jerking the car; there are at least 4 ways to do so, but they are not as good as heel-toe downshifting:
1. Before slowing down, downshift to a gear suitable for the turn and blip the accelerator before engaging the clutch. Of course, that is not always possible since it could, depending on the speeds involved, result in over-revving the engine.
2. Just before beginning the turn, downshift, and blip the accelerator before engaging the clutch. Of course, one has to reach a low enough speed well before reaching the turn to permit time to execute the downshift.
3. Downshift while turning, which is awkward since one has to remove a hand from the steering wheel to shift - not a good idea.
4. Downshift after completing the turn, including blipping the accelerator before engaging the clutch. That is also awkward since one cannot accelerate immediately after completing the turn.
I've thought about having my accelerator modified to make heel-toe downshifting possible, but haven't done so. Fortunately, the problem does not exist on my motorcycles since the controls are different.