All braking system components play a crucial role in maintaining the stability of your vehicle and keeping you safe on the road. Drivers are generally advised to have their brakes inspected once every six months, even if no problems have been detected, as this could help to prevent an accident and prevent costly damages. There are several factors that can affect these components, such as the driving conditions, vehicle weight, driving style, and wheel alignment. Keep reading if you would like to know more about how to detect damage and wear, and how to maintain your car’s brakes.
Key brake components
Discs/rotors: The components are attached to the wheel hub and rotate with the wheels. The vehicle stops moving due to the friction between the pads and discs when they come into contact with each other.
- Brake pads: A pad is made up of a metal backing plate and a friction material lining. The wheels slow down when the pads are pressed against the discs. Each wheel has one pair and they have to be replaced as a set (4 pads per axle).
- Brake fluid: A hydraulic fluid which is used to amplify the force applied to the pedal and transfer the pressure to other components of the braking system.
- Master cylinder: This component controls the hydraulic fluid pressure.It directs the fluid through a valve and a system of hoses to the wheel cylinders.
- Pistons: The pressure actuates the pistons which press the pads.
- Caliper: The pads and pistons are mounted inside the calipers. The brakes work slightly differently depending on the caliper design.
- Drum: Some cars feature drum brakes which work using pistons and shoes instead of calipers and pads.
How to check the brakes
First of all, you will need to raise the vehicle with either a vehicle lift or a jack, jack stands and wheel chocks. Once the vehicle is secured, you can remove the wheels to gain access to the components.
- The discs:
The surface of the discs should be smooth and even. You can inspect them for heavy rust, dents, uneven wear, scratches and scoring without removing them. Minor cases of rust are often harmless, although the rust may worsen over time if left untreated. Do not remove a disc without removing the caliper first.
- The calipers:
CAUTION: The calipers will be hot if the vehicle has been driven recently. Handle with caution.
If the caliper is cool, you can check to see whether it is loose by carefully shaking it. A loose component can cause damage to the rest of the braking system.
- The brake pads:
The caliper dust cover should have an inspection hole or slot for checking the brake pads. If the pads are visibly much thinner or have worn down to the metal plates, they will need to be replaced. If they are less than ¼ inch thick, new ones should be installed.
- The brake fluid
Locate the brake fluid reservoir on your vehicle and check the colour and fluid level in the tank. The fluid should not be too dark and there should be a sufficient amount left in the reservoir. Do not leave the master cylinder or brake fluid exposed for too long, and make sure to clean the sides of the cap before removing it to avoid contamination.
When and how to replace the brake pads
The pads usually last between 15,000 and 20,000 km, varying depending on their quality, road conditions and other factors. Forgetting to replace them can be costly and you may eventually need to replace the discs too.
Most modern pads include a wear indicator, which will cause a high-pitched squealing sound when it is time for a replacement. Other common signs include a grinding sound when braking, a burning smell, a longer braking distance and a pulsating or spongy brake pedal. If the vehicle pulls to one side when braking, this could also be a sign of uneven wear.
The replacement procedure:
Please note: This is just a general replacement guide, please check the vehicle’s repair manual for detailed, step-by-step instructions.
- First, open up the bonnet and unscrew the cap on the brake fluid reservoir.
- Next, you will need to raise the vehicle using a lift or jack.
- Unscrew and remove the wheel.
- Remove the brake caliper fasteners.
- Pull the pads away from the disc and detach the caliper.
- Clean the mounting points using a wire brush and brake cleaner.
- Install the new components.
- Seat the caliper piston.
- Reassemble the parts in reverse order.
- Lastly, you will need to make sure the fluid is flowing properly. Pump the brakes by pressing the pedal a few times while the engine is turned off, until it becomes firm. Do not press it all the way down. Remember to replace the reservoir cap afterwards.
Changing the brake fluid
One of the main issues with brake fluid is that it is hygroscopic, meaning that it absorbs moisture over time. Brake fluid has a lower boiling point when it has a high water content and makes the braking system less effective. Moisture and contamination can also cause parts of the system to corrode. If the fluid is too dark or smells burnt, it is probably too contaminated. If the fluid levels are unusually low or it has to be changed very often, there could be a leak. In this case, make sure to inspect the hoses and pipes, and look for leaks around the vehicle.
Different car manufacturers will have different recommendations for replacing the brake fluid depending on the vehicle model. The fluid may also be affected by the driving conditions.
Signs that you need to change the fluid:
- A soft brake pedal
- A burning smell when braking
- Squealing or grinding noises
- The ABS light comes on
How to change the brake fluid:
Caution: Be careful not to overfill the tank and make sure to use the correct brake fluid as specified in the car owner’s manual. Brake fluid is toxic! Avoid contact with eyes and skin.
- Drain the old fluid from the reservoir. To do this, you can use a turkey baster or syringe. Place the old fluid in a suitable container and remove as much as possible.
- If possible, use a lint-free cloth to wipe around the inside of the tank.
- Now fill it back up to the maximum line with new fluid from a sealed container.
- Replace the cap on the fluid reservoir.
Next you will need to flush the system:
- Raise the vehicle using a vehicle lift or jack and jack stands and remove the wheels.
- Locate the bleeder valve for the first wheel and loosen its fasteners.
- Attach one end of a hose to the valve and place the other end in a container, such as a jar, to collect the liquid.
- Next you will need an assistant to help you pump the brakes. Tell them to press the brakes 4-5 times with the same amount of force that they would normally use to brake the vehicle. Then,while they are holding down the pedal, open the valve to let the old brake fluid out. You may have to repeat this process until the old fluid has been removed. The pedal will start to sink, but the pressure should remain constant. When the darker old fluid has fully drained and you can see the new fluid coming through the valve, this step is complete.
- You will need to repeat this flushing process for the other wheels.
- Once this is complete, top up the brake fluid once more.