The brake pad is a steel or cast iron disk that rotates with the wheel hub. This is straddled by a calliper carrying a brake pad on either side. The more sophisticated systems have ventilated discs, and some systems have devices that automatically prevent the wheel from locking up in an emergency stop. Worn brake pads or a damaged disc will affect the effectiveness of the braking operation.
There are two types of braking systems used on a vehicle: the floating calliper type and the fixed calliper type. The floating calliper type has a single piston and calliper which moves across the disc as the pads wear, and thus takes up the excessive wear. The fixed calliper model has two pistons, which move closer to the disc as the brake pads wear.
Brake pads must be replaced when the thickness of the friction material is at 2mm thick, or when uneven wear is evident on the brake pads.
Both sets of brake pads on the same axle should be replaced at the same time. Should only one set of brake pads be replaced, the vehicle will brake unevenly and pull to one side during braking.
Loosen the wheel securing nuts. Jack up the front or back of the vehicle and use trestles to support the vehicle. Ensure the handbrake is applied to prevent the vehicle from moving forwards or backwards while supported by the safety trestles. Remove the wheels from the vehicle.
Open the bonnet and remove the brake fluid reservoir cap. Wrap a thick absorbent cloth around the reservoir filler neck to soak up any brake fluid which might overflow.
Floating Calliper Type: Remove the piston housing before changing the brake pads. The guide pins screw in, and are recessed in a rubber shield. These will require an allen key or spanner to remove them. Loosen and remove the pins, and slide the calliper housing off. Remove the pad retaining springs at the same time as the calliper housing is removed. Carefully remove the worn brake pads, always removing the outside pads first.Fixed Calliper Type: This design has two pistons and two guide pins. First remove the clips on the guide pins using a long nose pliers and tap out the pins using a blunt punch and hammer. Remove the springs. Carefully remove the worn brake pads, always removing the outside pads first.
Examine the surface of the brake disc for scores deeper than approximately 0.4mm, and for signs of obvious damage or poor alignment. If there is obvious damage, consult a brake specialist.
Use a special retraction tool to force the pistons back into the calliper housing. Be especially careful when doing this so that the piston and surrounding rubbers are not damaged. Examine all the seals and rubbers for obvious visual damage or leaks, and replace where required.
Fit the new brake pads, starting with the outer pad first. Replace the retaining plates and refit the calliper housing and guide pins. Remember to lubricate the guide pins. Repeat the above procedure with the brakes on the opposite side of the vehicle.
Refit the wheel of the vehicle. Pump the brake pedal a few times to enable the new brake pads to make contact with the pistons and brake disc. Remove the trestle and lower the vehicle to the ground.
Remove the waste cloth from the reservoir filler neck and check the brake fluid level. Top up the brake fluid level if necessary, and replace the reservoir cap.
USEFUL TIP 1:
Be gentle on the brakes for the first few hundred kilometres. This will allow the brake pads to bed in properly
USEFUL TIP 2:
Brake fluid should be replaced every 12 to 24 months, and a regular inspection of your vehicle’s brake components is essential to your safety.