Welcome to part 10 of this racing concepts series. Remember: the most dangerous words in the English language are “I already know that.”
For me to thoroughly explain left foot braking, we need to break it down into two categories:
- Driving on the road.
- Driving on the track.
Left Foot Braking Part 1: On the Road
The topic left foot braking is something that I am extremely adamant about.
I have no idea why it’s not taught in driver’s education schools.
Not only is it faster on the track, but it’s much safer on the road.
In this section, we will only discuss its advantages during everyday road driving.
Classic Right Foot Only Method
Driver’s education schools teach the typical road driver to operate the gas and brake pedals with their right foot, switching back and forth as the situation requires.
During an emergency braking situation, a driver must go through the following steps while using the right foot only method.
Emergency Braking Situation Steps
- The driver must realize there is a need to stop the vehicle.
- The driver must move their foot from the gas pedal to the brake pedal.
- The driver must depress the brake pedal to begin slowing the car.
During each of the steps, a small amount of time will elapse.
The time it takes to realize that the car needs to be stopped until the time the driver begins moving his right foot toward the brake is called reaction time.
The time elapsed between the driver moving his foot from the gas pedal to the brake is the motor function time.
Lastly, the distance that the car travels between the application of brakes and reaching a complete stop is called the braking distance.
Imagine that a car is moving at 35 mph down a populated road. Without warning, a dog runs out 100 feet in front of you.
In a situation where the driver is using the driver’s ed method, he must follow the three steps of emergency braking.
Let’s say he has a reaction time of .83 seconds, a motor function time of .92 seconds, and a stopping distance of 55 feet (figure 24).
In the first two stages of the emergency braking process, the car does not slow down.
In other words, during the driver’s reaction time the vehicle has traveled 42.6 feet.
During motor function time the car has traveled another 47.2 feet.
Since the car needs an extra 55 feet to reach a complete stop, the total distance covered in this scenario is 144.8 feet.
Unfortunately, the dog doesn’t stand a chance.
The Left Foot Braking Method
Left foot braking is an acquired art.
Since most of us were trained to brake with our right foot, using the left will initially feel clunky and awkward.
But after a bit of practice, it will begin to feel more normal.
But this technique does not need to be used all the time. During 90% of road driving you will find the driver’s ed method to be adequate.
Left foot braking is preemptive tactic to be used when approaching objects that obscure your vision, behind from which obstacles might suddenly present themselves (such as a row of cars that a pedestrian could step out from between).
A great driver is always thinking ahead and prepared for the worst.
To mitigate the potential danger of this situation, the driver should hover their left foot over the brake pedal without engaging it.
This defensive preparation is the key to successful left foot braking.
And, as you’re about to discover, it can be hugely advantageous to you and anything (or anyone) that leaps into your path.
Let’s use the same scenario as before. A car is traveling at 35 mph and a dog jumps out 100 feet in front of you.
Since the driver’s left foot is already hovering over the brake pedal, an entire step in the emergency braking process is eliminated (figure 25).
While using the left foot braking method, there are only two stages of emergency braking: reaction time and stopping distance.
If we use the same reaction as before, .83 seconds, the car will travel 42.6 feet.
However, since there is no motor function time, because the left foot is already poised above the brake pedal, the driver can immediately begin applying the brakes.
And, using the same stopping distance of 55 feet, the total stopping distance in this scenario is 97.6 feet – 47.2 feet shorter than with the driver’s education method.
As a vehicles speed increases, its braking distance will also increase.
Using the same motor function time as the first scenario, .92 seconds, you can see how much braking distance can be saved using left foot braking at various speeds.
- 45 mph = 60.72 feet
- 55 mph = 74.2 feet
- 65 mph = 87.7 feet
- 75 mph = 101.2 feet
Left Foot Braking For The Track
While left foot braking on the road is strictly to reduce stopping distance, its goal on the race track is to maximize acceleration time, control weight transfer, and provide maximum grip during braking and corner entry.
The benefit of left foot braking is creating a smooth transition from acceleration to braking.
I have found left foot braking to be extremely effective during autocross racing.
Let’s get one thing out of the way.
Left foot braking is completely compatible to vehicles with manual transmissions.
I often hear the question, “How can I use the clutch pedal while I’m using my left foot to brake?”
The short answer is that you don’t. The long answer is comprised of the following:
- Avoid downshifting during a corner. I frequently witness autocrossers (even experienced ones) execute a downshift at the apex.This is a waste of time and traction.And, if coupled with poor technique, it can create unnecessary forces that can damage your clutch, transmission, or differential.
- If you must downshift before a corner, you won’t use left foot braking in that corner.Left foot braking is only used in corners that allow you to remain in one gear. You cannot left foot brake into a corner with the intention of downshifting before that corner.
- Never downshift early so you can use left foot braking (Downshifting is its own topic and is discussed at length in a later post).
Imagine a car accelerating down a straight that leads into a right hand corner.
The corner has a small enough radius so that the driver will have to slow down, but a large enough radius so that he won’t have to change to a lower gear.
Let’s begin by considering the effects on the car by braking with the right foot.
As the driver reaches the point on the straight where he needs to apply the brakes, he will lift his foot off the throttle, move it to the brake pedal, and begin slowing the vehicle.
Along with covering unnecessary distance while changing pedals, like in the road example, two of his actions will have separate effects on the car.
- Lifting off the throttle. When the driver removes his foot from the gas, some of the cars weight will transfer toward the front of the car.
- Braking. When he begins applying the brakes, he induces a second (much more substantial) wave of forward weight transfer.On the accompanying graph (Figure 26), you can see that these two separate weight transfers combine for a front heavy weight distribution, lightening the rear and reducing its ability to provide optimum grip.
Let’s use the same scenario to demonstrate left foot braking.
This time when the driver reaches the braking point, his left foot is already poised above the brake pedal.
As he releases the throttle pedal he is also applying the brakes, creating a single smooth weight transfer (also figure 26).
Since the driver in this example only caused one transfer of weight instead of two (even though they braked the same amount), his weight distribution will be closer to neutral.
This creates less weight transfer and gives the driver more favorable weight distribution as he enters the corner.
This allows for higher levels of balance and traction for vehicle.
Remember, less weight disturbance equals a faster car.
NEXT WEEK: Downshifting
The next part in this series is only a week away. Go back and read through this again. Make sure you truly understand what you just saw, because the series progressively builds as it continues.