Braking
Published: July 23, 2013; updated: May 19, 2015
Today we are going to look at proper braking technique.
Braking might seem easy, but it offers plenty of challenges for novices as well as plenty of nuances for advanced drivers to take advantage of. Many novice drivers do not use the full braking capability of their cars - simply put, they do not press the brake pedal hard enough. For advanced drivers, left foot braking and trailbraking permit much quicker corner entries and greatly improved control of the car.
Basics
A braking application has four components:
- Application point, which is when you start pressing the brake pedal;
- Ramp up, when you are increasing brake pedal pressure;
- Hold, when you are holding the brake pedal at its maximum depression;
- Release, when you are getting off the brake pedal.
Let's look at each of these components individually.
Braking Point
Braking point is the point on the track where you start applying the brakes. Hitting the brake pedal is easy; hitting the brake pedal as late as possible is hard, and often scary. The recipe for braking late on the straights with the minimum amount of stress is as follows:
- Pick a safe braking point.
- When the car arrives at this braking point, apply maximum braking (see below for brake ramp up and hold).
- Continue braking until the car reaches appropriate turn in speed.
- If the car has not yet arrived at the turn in point, coast until the turn in point. On the next lap, move the braking point closer to the turn in point by about half the coasting distance.
If you follow this recipe for braking, you will be braking late and hard in no time.
The important part of the recipe is to apply full braking power regardless of how early you start to brake. If you apply partial braking power because you think you started braking early, or if you partially or completely get off the brakes before braking is completed, you don't know by how much you can move your braking point toward the turn on the next lap.
Brake Ramp Up
Once you start pressing the brake pedal, you want to move it as quickly as possible until the full depression. The caveat is doing so without exceeding the grip available on the front end of the car.
Assuming you are on throttle prior to brake application, the weight is transfered to the rear tires. At that moment the amount of braking the car can do is less than if the car was not accelerating. Once the car starts to brake, weight transfers to the front tires, which increases the grip available for braking.
What this adds up to is you want to move the brake pedal just slower than the rate at which weight transfers from rear to front tires. This also means you need to be smooth on the brakes. Stabbing the brakes is generally inferior to a smooth brake application, provided smoothness does not make pedal movement excessively slow.
Brake Hold
This is the part of the braking zone where the brake pedal is not moving and the car is decelerating at a constant forward deceleration rate which, ideally, is not far off maximum attainable by the car.
In a car equipped with ABS brakes, you generally want to be applying just less brake pedal pressure than ABS threshold. ABS works by releasing the brakes, therefore when it is active you are typically getting less braking torque compared to staying just under the ABS engagement.
In a car not equipped with ABS, you want to apply just less brake pedal pressure than the point at which your tires begin to lock up and slide.
When braking hard in a non-ABS car, a very important point to remember is you have no steering control when the front tires are locked under braking. If you lock up the tires, you should get off the brake pedal to allow the tires to spin, then get back on the brakes. Repeat as necessary.
Most cars when driven reasonably hard cannot come to a stop before running out of track when coming into a corner too hard. If you come into a turn too fast, you want to slow the car down as much as possible in whatever straight line braking distance you have available and then get off the brakes partially or completely and turn the car to follow the pavement.
Another thing to pay attention to is downshifting while braking. It is natural to lift the right foot off the brake pedal while blipping throttle. This is very obvious on data if you have it. Otherwise you can still feel the car not decelerating while you blip throttle. One solution to this issue is to avoid unnecessary downshifts - instead of shifting 5-4-3, shift directly 5-3.
Brake Release - Smoothness
It is important to release the brakes smoothly. The reason is weight transfer - just like abruptly getting off the gas at high RPMs causes the car to lurch forward, abruptly releasing the brakes creates a sudden weight transfer that can unsettle the car.
Even if it were possible to instantly releae the brakes, this would not be the fastest way to drive. The reason is turn in must be smooth, and therefore, while the car is transitioning from going straight to maximum turning, some grip remains that can be used for braking. Timing brake release, covered below, and trailbraking take advantage of weight transfer to front tires to aid in rotating the car into a corner.
Brake Release - Timing
Brake release should be timed with turn in, again due to weight transfer. Under full braking weight is moved to the front tires, therefore the front tires have more grip compared to a neutral car. Turning while the weight is over the front tires permits the car to change direction more rapidly compared to a neutral car. We say that the car "turns better" in such a case.
Novice drivers typically finish the braking significantly before they get to their turn in point. The goal for novice to intermediate drivers is to time braking such that they are finished with it just before they start the turn. In terms of driver inputs, the driver gets off the brake pedal and immediately starts to turn the steering wheel.
Intermediate drivers overlap braking and turning a little. They are still mostly braking in a straight line prior to the turn but they now finish releasing the brakes just after they start the turn. A typical overlap might be half a second to a second. Note that the driver begins to release the brakes prior to turn in - it is impossible to turn a car which is under full braking!
Finally, advanced drivers use trailbraking to achieve significant overlap between braking and turning, as much as 2-3 seconds in corners like Summit Point turn 1 or VIR turn 1.
Left Foot Braking
Using the left foot to operate the brake pedal permits finer control over the braking process and makes the driver faster. Left foot braking is covered in a separate essay.
Trailbraking
Extending the brake hold phase into the corner is known as trailbraking. Trailbraking takes advantage of weight transfer to the front tires to increase corner entry speed, and reduces the distance traveled in corner entry phase of a corner for a further reduction in lap time. As left foot braking, trailbraking has its own essay.
Tagged: weight transfer, novice, intermediate, braking
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