Electronic Stability Control vs Traction Control: 3 Differences

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There are many different systems within cars that help to make them safer to drive, and two of the most common are Electronic Stability Control (ESC) and Traction Control (TC). But what are the differences between the two systems?

The 3 differences between Electronic Stability Control and Traction Control are:

  1. Traction control is used to limit wheelspin
  2. ESC is used to help guide the car in the right direction
  3. Traction control may use other components while ESC usually only uses the brakes

This is a simple way of saying what each of these systems do, but more differences arise when you consider how they work and their applications. Below, I look at each one in more detail, and find out where each one comes into play when you’re driving.

An Overview Of Electronic Stability Control

Electronic Stability Control, or ESC, is also sometimes called Electronic Stability Program (ESP) or Dynamic Stability Control (DSC). This system detects and reduces your loss of traction. It does this via a complex system of sensors that monitor the amount of grip experienced by each wheel.

It then uses automatic application of the brakes at individual wheels to guide the car in the right direction, which we will discuss in more detail below. It may also reduce the power of the engine in some cars, but it usually only uses the brakes. ESC does not improve cornering, and instead only minimizes the loss of control that the car experiences.

Your car's ESC essentially monitors how well your car is carrying out what you ask of it, by measuring things like steering input and the speed of each wheel.

When Is ESC Used?

Minimizing The Loss Of Control

Electronic stability control systems minimize the loss of control experienced by the driver by slowing down the individual wheels when required. The brakes are applied to the individual wheels in the way that the ESC system ‘thinks’ will help to allow the car to go in the right direction.

This is the main idea behind the electronic stability control system, as it is used in situations when the car is not travelling in the direction that the driver intends. It does this by measuring the angle that the steering wheel should be making the car turn and compares it to the amount that the front wheels are turning and by measuring the amount of traction at each wheel.

Oversteer

The wheels that the ESC applies the brakes to will depend on the way that the car is losing control. If the car is going into an oversteer situation for example (the back end tries to overtake the front), the brakes will be applied to the outer front wheel. This is because, as the rear wheels lose traction, the front wheels have more grip, and which one of these has more grip can affect the direction the car travels.

As the back end slides out towards the left-hand side, the ESC system will apply the brakes to the front left wheel. This creates torque (a rotational force) about the vehicle’s longitudinal axis, which can be thought of as a line straight down the middle of the car from the front to the back.

The right front tire’s rotation works to bring the back of the car back towards the center, almost ‘pulling’ on the opposite back tire (the back left). As the car begins to straighten up, the ESC performs this application and release of the brakes several times per second, and the fine tuning of the system means that the back end should straighten up without sliding the other way.

Understeer

If the car goes into an understeer situation, and for example the driver is trying to turn left but the car continues to travel straight on, then the ESC will apply the brakes to the inside wheels (the left) with the most braking force applied to the rear left wheel. This helps to rotate the car round to the left as the right wheels are rotating faster.

The video below is an old one, but Jason from Engineering Explained still does an excellent job of concisely illustrating how ESC works.

Disadvantages Of ESC

ESC does have the issue that it can make drivers complacent, as they may feel like they can push their car further than its limits. The problem is that ESC does not always save the car from losing control, and with extreme speeds and sharp turning the car will still inevitably lose control. So, ESC cannot be treated as a complete fail safe, and there is no substitute for safe driving.

In race cars, ESC is not always useful, as a lot of drivers may prefer to use some understeer or oversteer within their driving style. ESC will limit their ability to use either one, or if it comes on at high speeds the car could snap back into a straight line unexpectedly. This could prove dangerous at high speeds with other cars around you.

KEY POINTS

• Your car’s electronic stability control system helps you maintain control of your car

• It slows the car’s wheels down individually when it detects a loss of control

• It’s typically not used in motorsport

An Overview Of Traction Control

Traction control is designed to prevent the loss of traction when the car is accelerating. Wheels can lose grip for a variety of different reasons, and intense acceleration can be one of them. Traction control applies the brakes to the wheels that have lost traction in order to regain it and allow the car to accelerate effectively.

Traction control systems are more complex than a simple application of the brakes, and they often involve power reduction within the engine itself. This can itself involve a reduction of the spark sequence inside the individual cylinders of the engine, or it can be used to reduce the fuel supply, which would also limit the power delivered to the wheels.

When Is Traction Control Used?

Loss Of Traction

Traction control is activated when the car detects a loss of traction, rather than a loss of control. Although this can often be indistinguishable from a loss of control, and both ESC and traction control can indeed turn on in the same circumstances, traction control is most often applied when the car loses traction under acceleration.

Your car can lose grip for a number of reasons, such as an uneven road surface or if it is wet. However, when the car is accelerating, such as during a race when the driver may put his foot to the floor when exiting a corner, a loss of traction may cause the wheels to spin. This means that not all of the power is being transferred to the tires onto the road.

To combat this, traction control turns on to limit the power being supplied to the turning wheels. As I have already mentioned, it can do this by applying the brakes or by temporarily reducing the power of the engine. It is also used most often during a corner and particularly upon the exit, when the driver tries to accelerate from a low speed to a high one in a short space of time.

Below is another video from Jason at Engineering Explained where he very concisely sums up what traction control does.

Front-Wheel Drive

If you are driving a front-wheel drive car and you corner quite aggressively, you will be at risk of going into an understeer situation. This is because as you accelerate, the weight of the car shifts towards the rear, and the front tires are prone to losing traction. This reduces their ability to turn effectively, and so the car continues in a straight line as you turn the wheel.

In this situation, traction control limits power to the front wheels, causing them to grip the road and regain the traction that they need in order to turn the car.

Rear-Wheel Drive

Rear-wheel drive cars are more susceptible to oversteer. This is because, although the weight is transferred to the back of the car under acceleration, the rear tires may break this increased traction through rapid acceleration, causing wheelspin. Traction control works to reduce the power at the rear in this case, allowing the spinning wheels to regain traction and break out of the oversteer.

Traction control therefore has its use in a race car as it allows for more grip at the exit of a corner when the driver presses the accelerator pedal. For this reason, some motorsports limit the use of traction control, such as Formula 1, which banned it completely in 2008. This is because it can be seen as a driver aid, reducing the skill required to drive the car on the limit.

Disadvantages Of Traction Control

Traction control also presents the possibility of driver complacency, as you may feel like you can push your car past its traction limits when accelerating. Also, in off-road situations, you may actually want the wheels to spin in order to get you out of some situations, such as when the car is stuck in mud.

If used on the track, it may limit the car’s power at the wrong time, similar to the way that the ESC system may cause the car to straighten up at an undesirable time. This could cause the driver to lose vital milliseconds, which add up over the course of a race. Not only that, but the system can be expensive to repair if anything goes wrong. Many motorsports ban the use of traction control.

KEY POINTS

• Traction control helps you maintain control over your car under acceleration

• It stops the wheels from spinning when it detects a loss of traction

• Like ESC, many motorsports ban the use of traction control

Final Thoughts

Electronic stability control and traction control are two systems used within cars to give the driver more control in certain situations. ESC is used to prevent or reduce the loss of control through oversteer and understeer, while traction control is used to give the tires more grip under acceleration. Both have implications on and off the track, much like ABS does too.