This article is courtesy of EuroCarParts. There's a complimentary video below:
Why change? Brake pads consist of a backing plate and friction material. It is the friction material that comes into contact with the brake disc. Over time the friction material wears down and your brakes become less effective at stopping your vehicle. The manufacturer of your vehicle will specify a minimum thickness of the friction material before the brake pads need to be replaced.
Tools required: -Lifting jack
Before you get started: When checking your brake pads you should look at the inner and outer parts as they can wear at different rates. If your vehicle is fitted with alloy wheels, looking at the thickness of the outer pad is not enough. Let’s compare the new brake pads with a worn set. Brake discs are made of cast iron and like brake pads they can wear over time. Depending on your driving style brake discs have a longer service life than the pads and do not require replacement every time pads are replaced. When you are inspecting brake discs you should check both sides. You should check for:
Corrosion – this is more common on rear brake discs.
Scoring on the surface where the brake comes into contact with the disc. This can happen if the friction material wears out completely and the metal backing plate comes into contact with the brake disc.
Distortion – the surface of the brake disc is uneven. Brake discs wear overtime and become thinner. The manufacturer of your vehicle will specify the minimum thickness of a brake disc. A special tool is required to measure the thickness, however a good indication is the size of the ridge between the inner edge of the brake disc and outer edge.
Some rear brake callipers will also operate the handbrake. If this is the case, you will require a special tool to wind the calliper piston back into the calliper (rather the force the piston back with a G-Clamp as you do with the front callipers). A way to check for this is to look to see if the handbrake cable is attached to a rear brake calliper. If the handbrake cable is connected to the rear hub your vehicle is fitted with handbrake shoes and a special tool is not required. Finally if your vehicle is fitted with an electric handbrake you may need to use specialist diagnostic equipment to put the vehicle in service mode to enable rear brake pads to be replaced.
Stage 1 – Set up and preparation 1. First step is to open the bonnet and remove the cap off the brake fluid reservoir, to give the pressure in the system somewhere to escape. There is a risk that the brake fluid could overflow during the task so have a can of water on standby to wash off spilled brake fluid because it can damage the vehicles paintwork.
2. Get a piece of paper and write down ‘PUMP THE BRAKE PEDAL’ and place the paper behind the steering wheel as a reminder to do this before driving off after completing the job.
Stage 2 – Raise the vehicle 1. Next task is to raise and support the vehicle. New braking components should be replaced in pairs on the same axle. Remember never get underneath an unsupported vehicle. We recommend leaving the road wheel under the vehicle to act as secondary precaution.
2. You now have access to the brake assembly.
3. Unplug the brake pad warning sensor (if fitted).
4. Remove any retaining clips.
5. Remove the retaining bolts that secure the brake calliper to the carrier. Always support the calliper to ensure no strain is put on the flexible brake hose.
6. You can remove the brake pads now. Sometimes the pads might be stuck in the carrier. Use an old screwdriver to prise them off.
7. Clean any surface rust and dirt from the brake pad carrier with a wire brush. The new brake pads should now slide freely on to the carrier.
8. Inspect the brake discs now, remember to check both sides.
9. If your brake discs are serviceable move onto step 21.
10. Some brake pad carriers need to be removed to enable the removal of the brake discs.
11. On most vehicles the brake disc is secured to the hub using a screw or the combination of road wheel and wheel studs/nuts. Some vehicles the brake discs also form part of the hub, which houses the wheel bearing.
12. When removing a securing screw. You might need to use two wheel studs to stop the disc from rotating.
13. Corrosion will cause the brake disc to stick to the face of the hub. If this is the case, use a hammer to shock the brake disc, remembering to screw two wheel studs/nuts into the hub to stop the disc falling to the floor, or on your foot.
14. Remove the studs/nuts from the hub and remove the old brake disc.
15. Take a wire brush and clean up the face of the hub and the lip where the brake disc is mounted. It is important that the brake disc sits squarely on the face of the hub, so don’t scrimp on time here.
16. Refer to the brake disc manufacturer. Some discs are coated with a substance to prevent corrosion when in storage. This must be removed using brake cleaner (available as a spray from your local ECP branch).
17. Secure the brake disc to the face of the hub and re-fit the securing screw if required.
18. Refit the brake pad carrier.
19. Attach the new brake pad warning sensor to the correct brake pad (if required).
20. Add some brake pad lubrication to the edges and back plate of the brake pad where it comes into contact with the carrier and brake calliper. Be careful not to get grease/lube on to the friction material.
21. If the rear calliper operates the handbrake, you will need to use a special tool to wind the calliper piston back into the housing, called a wind-back tool. Warning: some callipers incorporate a left-hand thread that means you need to turn the calliper piston clockwise “un-doing” to wind the piston back into the calliper.
22. Install the calliper piston wind-back tool. Spray some WD-40 on the piston dust cover to stop it snagging and tearing. If you do damage the piston dust cover it will need to be replaced.
23. Wind the tool in the correct direction to retract the calliper piston, to enable the calliper to fit over the new brake pads.
24. Remove the calliper wind-back tool.
25. If your vehicle’s handbrake is not operated by the calliper, retract the brake calliper piston back into the calliper to enable the calliper to fit over the new brake pads. You can use a G-clamp or swan neck pliers.
26. Check for any overflowing brake fluid from the brake fluid reservoir.
27. Refit the calliper over the new brake pads.
28. Secure retaining bolts.
29. Refit any retaining clips.
30. Plug in the brake pad warning sensor. If the vehicle does not have brake pad warning sensors use cutters to remove and discard the sensor from the new brake pad.
31. Take some time to recheck all of the retaining bolts and clips.
32. Re-fit the road wheel and move onto the other side.
33. Re-fit the brake fluid reservoir cap.
34. Remember the note you placed behind the steering wheel! Gently depress the brake pedal to close the gap between the brake calliper, brake pads and the brake disc. You might need to pump the pedal several times. Also apply the hand brake several times to adjust the travel of the hand brake.
35. When you have completed the job check the brake fluid level is between the maximum and minimum level indicators on the brake fluid reservoir. The level will be higher because the new brake pads are thicker than the worn ones. Dispose of the worn components.
36. When driving the vehicle you will notice that brake pedal will feel softer until the brake pads have bedded in. You should try and avoid heavy braking during this period (up to 100 miles).
37. Brake fluid should be renewed every two years due to its ability to retain moisture over time.