Brake Systems

How to maintain your brakes for better braking and safety, plus inform you on some of the latest technology used on modern vehicles and what this technology means for you as the driver.

Maintenance

To make your vehicle slow down when you press the brake pedal, a special brake fluid is pressurised in a cylinder under the bonnet of your car. This creates pressure in hydraulic lines that run to the wheels of your car, compressing the calipers or cylinders of your brakes. The calipers or cylinders push against discs or drums, respectively, creating friction and slowing your vehicle down.

The brake fluid is a special fluid and the choice of fluid is very important in effective braking. Brake fluid (like most liquids) will not compress which makes it ideal for transferring pressure. Brake fluid in all vehicles is deemed DOT3, DOT4 or DOT5.

DOT3 and DOT4 brake fluid are glycol based and hydroscopic meaning they absorb moisture or water from the air. For this reason they need replacing periodically (every two years or every 40,000km). Moisture absorption results in the brake fluid’s boiling point being reduced which can lead to the brake fluid boiling when under load, this in turn causes the fluid to become compressible loosing its ability to transmit force. Of course, this can make your brake performance very poor.

DOT5 fluid is silicone based and will not absorb moisture but any water that does get in the system will form pure water pockets that cause corrosion if not removed. Corrosion in the brake system will cause moving parts to leak, stick or fail.

To check your brake fluid level open the bonnet and put the stay up, the fluid is in a reservoir mounted on the firewall usually on the right-hand side. The fluid level should be between the low and full marks indicated on the clear plastic. If the level is low, remove the lid and top it up from a sealed brake fluid container.

Remember to keep your brake fluid in a tightly sealed container to avoid moisture absorption. To check if your vehicle requires DOT3, DOT4 or DOT5 consult your owner’s manual, ask your mechanic or see if it is specified on the brake fluid cap under the bonnet.

Two important things about brake fluid: DOT3 and DOT4 brake fluids are corrosive to paint; so don’t spill it on your car. If you do, wash it off with water immediately. Also, none of the different types of brake fluid should ever be mixed. They can react badly with each other and corrode your brake system.

The next item to maintain is the brake pads. Your vehicle’s brake pads will wear out over time depending on your vehicle and driving style. Most brake pads are fitted with a wear indicator that will cause a squealing noise when the brake pads are low. This noise means the pads need replacing now. If wear continues and causes metal-to-metal contact between the discs and the pad backing material the discs will need to be skimmed or replaced, which can be expensive.

The fitment of good quality brake pads and brake fluid can increase your braking performance and driving safety markedly.

The following brake systems are designed to aid in your safety.

ABS

ABS stands for Anti-lock Braking System. It is most effective when stopping on slippery surfaces such as wet or icy roads.

When the wheels are locked up under severe braking you loose steering control and the stopping distance is increased as a skidding wheel has less traction than a non-skidding wheel. ABS controls pressure to each braked wheel individually, preventing this scenario. If the brakes are applied in an emergency situation ABS will keep each wheel on the verge of locking up resulting in reduced stopping distances and retained steering control for increased safety.

When ABS is operating the brake pedal will pulsate quickly, this is not a fault and is normal operation. It is essential that brake fluid, disc and pads are maintained for the ABS system to be effective.

ESP

ESP stands for electronic stability program. This works using your ABS system and a steering angle sensor to sense direction. If your car understeers and veers off the road while turning, the ESP system will apply the inside rear brake to ‘pull’ the car back in and around the corner safely.

Traction Control

The Traction Control module senses wheel slip under acceleration (via the ABS wheel speed sensor). The system will apply brake pressure to the slipping wheel to reduce the slipping, causing drive to be transferred to the other wheel on the axle, giving you traction. Traction control is useful in slippery driving conditions where the wheels of your car may lose traction under acceleration.

Traction control is used a lot in powerful late model vehicles, such as the Holden Commodore and Ford Falcon range. An added feature is the ability to turn the traction control off or on with the touch of a button. Some vehicles also disable this function at speeds above 40 kph.

ABS, ESP and Traction Control safety systems all have self-test lights on the dashboard, if one of the lights is flashing or illuminated after start-up it indicates a fault in the system and will need repair or investigation.