On the first day of our drivers' schools, all novice students will spend
their first track session doing several driving exercises. These exercises are
designed to teach two fundamental driving skills: threshold braking
and the management of weight transfer. You will use these two skills
constantly throughout your weekend, so it's important to learn them well.
Please refer to the track map in your Summit Point Guidelines brochure. We'll be doing three exercises: a slalom at the start of the main straight, a braking exercise at the end of the main straight, and another braking exercise approaching Turn 3. The remainder of the track between the exercises will be driven at low speed to give you a chance to orient yourself before your first regular driving session. There will be no passing during the exercise session.
Just prior to your exercise session, we will have you bring your car down to the "false grid" and line up to await your instructor, who will join you before you start. Only one car at a time is allowed to run a given exercise, so instead of having everyone wait in a long line at the first exercise, we'll break your group into thirds. You may be directed to bypass one or more exercises before you start your session; your instructor will tell you at which exercise you will begin.
Small "mini-cones," or pylons, mark the exercises. Don't worry about hitting the pylons; they won't hurt your car. In addition to the exercise pylons, there will be double pylons, called staging points, at the side of the track before each exercise. A course worker will control your entry into the slalom (Exercise 3); you will be directed to come to a full stop at the staging point before entering the exercise. The two threshold braking exercises (Exercises 1 and 2) have staging pylons but are unmanned. You only need to stop at an unmanned staging point if the exercise is occupied; otherwise, proceed past the staging point immediately.
When you apply your brakes, the frictional forces generated by your tires acting against the pavement slow your car down. The harder you press on the brake pedal, the larger the generated force is, and the faster you slow down--to a point. If you press too hard, your tires will be unable to generate the force being demanded of them, and they will lock (i.e., stop turning and begin sliding along the pavement). This sliding still generates some friction, but it is important to note that it is less than the amount that was being generated just before they locked.
Therefore, the quickest way to slow your car is to depress the brake pedal with as much pressure as is possible without locking your tires. This technique is called threshold braking. It is difficult to modulate precisely the amount of pressure you apply to the brake pedal, and it's even tougher if you're trying to turn the car at the same time. However, if you brake with the ball of your foot and your toes, you'll have a lot more control.
Because untrained drivers have difficulty braking with maximum effectiveness, antilock braking systems (ABS) were invented. If you apply too much brake pedal pressure, the ABS will modulate the pressure for you; you can feel this as a pulsation in the pedal and hear it as a chattering noise.
If your car is equipped with ABS, you can always just mash down on the brake pedal, steer, and let the ABS do all of the work for you. However, true threshold braking, i.e., applying maximal braking just before the ABS kicks in, will result in slightly shorter braking distances. Therefore, you should learn and practice threshold braking by modulating the pedal pressure to keep the ABS from activating.
Fundamentally, driving is all about friction: specifically, the friction between your tires and the pavement. The weight of your car generates proportional frictional forces (i.e., grip) at each tire, and these forces change profoundly when you accelerate, decelerate, or change direction; this is called weight transfer.
When you accelerate, weight transfers to the rear of your car, decreasing the grip available to your front tires and increasing the grip available to your rear tires. When you decelerate, weight transfers to the front of your car, enhancing front tire grip and decreasing rear tire grip. In a turn, weight transfers to the outer tires, reducing the grip of your inner tires. The amount by which grip changes at each tire in response to weight transfer is determined primarily by your car's suspension and its reactions to your inputs.
For a given corner taken at a given speed, each of your tires requires a certain amount of grip to maintain adhesion with the pavement. Higher speeds and tighter corners require correspondingly more grip. If weight transfer causes the grip available at a given tire to decrease below that which is required, it will lose adhesion and begin to slide against the pavement. If the sliding tire is at the front of your car, your car will understeer; if it is at the rear, your car will oversteer.
For More Information
Our Introduction to High-Performance Driving covers driving theory in more detail, including turn classification, vision, and the causes and solutions of understeer and oversteer. This publication is sent automatically to every applicant new to drivers' schools. If you did not receive a copy but want one, please contact our event registrar.
Exercise 1--Threshold Braking (on the Main Straight)
This exercise gives you a chance to practice threshold braking. When the previous car has cleared the exercise, accelerate briskly down the main straight. When you reach the first of the pylons near the end of the straight, begin braking and try to come to a complete stop as quickly as possible without locking up your tires or engaging your ABS. The row of pylons at the edge of the track will serve as a "gauge" of how quickly you've stopped. The faster you approach the braking pylons, the longer your braking time will be, giving you more practice time.
The proper technique is to build brake pedal pressure rapidly to a maximum just shy of locking your tires or activating your ABS. If you overdo it, don't jump entirely off the pedal. Instead, modulate your pedal pressure by reducing it just enough to release your tires or stop the ABS activation. With practice, you'll get a feel for exactly how much foot movement you need.
You will want to concentrate especially on minimizing the transition time, which is the time it takes you to switch from acceleration to full braking. This time directly translates into distance covered, and the faster you react, the shorter your braking distances will be.
Once you've stopped, drive slowly through the turn and on to the next staging area.
Exercise 2--Threshold Braking (Approaching Turn 3)
This exercise is identical to the preceding exercise (threshold braking is such an important skill that we want to give you ample time to practice it). When you reach the first of the gauge pylons, switch from acceleration to braking and try to come to a complete stop as quickly as possible. Use the pylons at the edge of the track to measure your progress.
Once you've stopped for this exercise, drive slowly around the track to the staging area for Exercise 3, located just after Turn 10.
Exercise 3--Straight Slalom (on the Main Straight)
A slalom is a set of spaced pylons located on the centerline of the track. The object is to drive around the pylons, alternately passing them on the left and right, while holding a constant speed. After each successful pass though the slalom, increase your speed a little bit.
As your speeds increase, you'll find it harder to avoid running over the pylons. This is because your car requires a finite amount of time from the moment you turn your steering wheel until your car actually changes direction (called the transient response time). First, the rubber parts in your steering system must flex. Next, the sidewalls of your tires must flex. Then the springs and bushings in your suspension must compress. Finally, your car will begin to change directions.
For some cars, this change will occur nearly instantaneously. For others, there will be a discernable lag between the steering input and the car's response. When you approach a corner at speed on the track, you must account for that lag, or your line will be off. For example, if you turn your steering wheel at the turn-in point for a given turn, but your car takes three-quarters of a second to respond, you'll actually be changing directions a car length or two after the turn-in point, and your line will be late.
The key, then, is to anticipate this delay in your car's reaction and turn slightly before you reach the next pylon, much as a skier turns his skis just before a gate to allow time for his skis to bite. The faster you go, the more distance you will cover before your car reacts to your steering input, and the earlier you will have to turn.
When you turn your car from side to side, you are transferring weight to alternate sides of your car. In doing so, the springs on the side opposite the direction you're turning (called the loaded side) will compress. Until your suspension has fully compressed, your loaded-side tires will not achieve full adhesion. Final compression will occur most rapidly if the turn is executed smoothly; if you turn abruptly, your loaded-side springs will actually compress too much, then expand again (or rebound) before finally settling down. During this time, you will not have effective control of your car.
If you enter the slalom too quickly, you will find that you must slow down to negotiate the first turn. However, when you decelerate, weight transfers forward, and your rear tires lose adhesion. If enough weight transfers forward, you could spin.
Moreover, any errors in placement that you make will multiply at each turn. That is, if you are late turning for the first pylon, you will have to make a sharper turn at the second to avoid hitting the pylon. If you're going too fast, you won't be able to make the turn sharp enough, so you'll be late for the second as well, and the third turn will have to be even sharper. This can easily cascade, and unless corrected, you may run off the pavement near the last pylon.
Therefore, you have to manage three things when driving the slalom. First, you must allow for your car's transient response time by turning slightly before each pylon. Second, you must minimize the compression time for your loaded-side springs by turning smoothly. Third, you must minimize errors in placement by looking ahead to the next pylon, rather than at the one you're passing.
Drive to and stop at the staging area for this exercise, which is just after Turn 10. Proceed to enter the exercise when signaled. To execute the slalom properly, you must enter at a speed slightly slower than you think is necessary, smoothly turn the steering wheel slightly ahead of each pylon, and maintain or slightly accelerate to keep the weight balanced from front-to-rear. If you do find yourself going too fast, recognize the symptoms early and abort the slalom by straightening your wheel instead of turning back for the next pylon. Run over one or more pylons if needed, but maintain control of your car.
Once you're through the slalom, proceed toward the staging point for Exercise 1. If the braking exercise is clear, you may enter it immediately. Otherwise, stop at the staging point and wait for the car in front to clear the exercise before proceeding.
Practice Makes Perfect
During your tour of the track between the exercises, your instructor will talk to you about the driving line, and you can practice putting your car in the correct location for each turn entry point, apex, and exit point. Remember that you will be driving at low speeds, and there will be no passing during this session.
You probably won't perform these exercises perfectly the first time. Perhaps you'll run over a pylon in the slalom, or maybe you won't be able to stop before you get to the last pylon for the braking exercises. Listen to what your instructor has to say about what you're doing and adjust your driving accordingly. By the end of the exercise session, you'll be doing much better, you'll be much more confident, and you'll be ready for your first regular driving session on the track. Most importantly, you'll have a solid foundation on which to acquire more advanced driving skills.
Revised March 2000