Cornering Part 2: Braking

The second part of corners is braking. To optimize the speed which you take through a corner, you want to focus on three questions: When do I start braking? How hard do I start braking? And should my brake pressure be constant? 

First, let’s start off with the brake point, the point on the track at which you begin to apply the brakes. The brake point will depend on the car you are using. If you are using a car with a higher top speed, let’s say the 499p Ferrari Hypercar, you would want to brake earlier as you would be carrying more speed into the corner. If you are using a slower car, like a Miata, you could afford to brake later as you carry less speed into the corner. Using this information, it’s really just a matter of trial and error to determine the optimal point at which you should begin to apply the brakes. The method we used in our trials was to first pick a conservative braking point, one at which we could easily hit the apex of the corner without locking up (I’ll get into what this means soon). Then we began to move the braking point back, until we either began locking up our front tires or we experienced too much understeer to be able to hit the apex.

Before we continue, I want to touch on a term I used in the previous paragraph: “locking up”. What is locking up? Locking up refers to “locking” your front tires, something that happens when the brake pressure you attempt to apply exceeds the grip of your front tires causing them to “lock” and skid on the ground instead of rolling. 

Here’s a quick video to show what I mean:

In this lap, Henry brakes too late going into turn 5 causing his tires to lock up. This can be seen from the smoke coming from his tires, a sign that the tires are skidding on the track rather than rolling on it. You can also see that because of locking up, the car no longer turns as the front tires are not gripping onto the track. In the bottom left, you can see the steering angle. Despite Henry turning the car to the right, the car continues to skid forward off the track.

Next, let’s consider brake pressure. Braking isn’t simply about slamming on the pedal–it’s about modulation. You typically want to apply the brakes firmly at first to maximize the deceleration while the car is still in a straight line. This initial peak pressure helps shed speed quickly, but as you approach the corner and begin to turn in, you should gradually release pressure to avoid upsetting the car’s balance. This technique, known as trail braking, allows you to maintain some braking force while turning, helping to keep weight over the front tires and increasing front-end grip. A general rule of thumb is to keep on the brakes until the apex of the corner, then begin to apply throttle. Applying too much brake pressure can lead to understeer or even lockups, especially if you are not smooth with your inputs. The key is to be progressive and controlled: brake hard initially, then ease off as you transition from braking to turning. To see the difference between trail braking and linear braking (applying constant brake pressure), let’s take a look at the effectiveness of trail braking by looking at some telemetry data from laps done by Henry in the Ferrari 499P at Spa. 

In the top graph, we can see two different lines. The blue line is the speed of the car in km/h and the green line is the amount of throttle Henry is applying as a percentage. In the bottom graph, the orange line is the brake pressure being applied as a percentage. The colored lines are from the lap in which Henry used trail braking and the white lines are from the lap where he used linear braking. 

As you can see, when Henry brakes linearly, he is forced to have an earlier braking point so as to not lock up the tires. This means that he maintains his top speed on the straight for a shorter amount of time; whereas when he uses trail braking, he is able to brake at a later point allowing him to carry more of his speed from the straight through the apex of the corner.

The benefits of this can be visualized in the images above. The dots are the positions of the car: the red dot being from the trail braking lap and the white dot from the linear braking lap. The trail braking car actually enters the corner behind the linear braking car because of a poorer exit from turn 1, however, trail braking enables it to carry a lot more speed through the corner and despite being behind going into the corner, it comes out ahead exiting the corner. 

The true efficacy of trail braking can be seen by the difference in speed between the cars at the point in which they begin to turn into the corner.

By lining up with the point at which the steering angle begins to deviate, we can find the point at which the cars have begun to turn into the corner. As you can see in the top graph, the trail braking car enters the corner 67.9 km/h faster than the linear braking car. 

In a later post, we will get into the physics and other details about trail braking.