It is important to keep tabs on brake wear. If the brake quality degrades too much then when you really need to stop, you might not! Poor brakes will also be a fail on an MOT. In the following picture you can see that the brake pads are not making contact with the full face of the disc. This was due to brake pad wear but the effects of this caused the disc face to become badly uneven. In this case, both the discs and pads were replaced.
To change the discs and pads, park with the handbrake on.
Slacken off the wheel nuts and locate a jack under the jacking point. Proceed to jack up the car, and remove the wheel. You may choose to use axle stands if you want to do both discs at the same time.
Remove the wheel.
Using a 13mm Socket, and a 17mm spanner to stop the slider moving, remove the top caliper bolt.
Swing the caliper cradle down, and if possible support using a stand (or similar) to avoid putting excessive strain on the brake hose.
Remove the brake pads by pulling them away from the disc.
With the pads removed, you can now remove the caliper. Using an E18 socket (or a 14mm socket fits well), locate the 2 caliper bolts with a bit of blind faith! These are located on the reverse of the hub-mount.
Undo the brake disc retaining screw using a T30 torx bit. Remove the disc.
Some brake discs have a protective film that needs to be removed by cleaning them with brake cleaner before fitting.
Line up the new disc, and tighten the T30 retaining screw.
Refit the caliper.
Fit the rear brake pad first. This is the one with the metal tag sticking out of the side. Use either copper grease or anti-squeal shims on the contact area on the back of the pad. The pad should not be jammed in the caliper. If it feels tight then fit it and remove it a number of times in order to scrape off some excess paint.
If your old brake pads had worn down then you will need to push the brake piston back in to create more space.
Try pushing it first. If it doesn't go then remove the cap off the top of the brake fluid reservoir.
Using the rear brake pad, pull the caliper and piston towards you. It will move, but very slowly.
Once complete, refit the brake fluid reservoir cap.
Fit the front brake pad in the same way as you did for the rear.
Close up the caliper and lock it in place with the bolt.
Ensure that the pad springs are correctly located on the caliper.
Refit the wheel and lower the car.
*** Pump brake pedal with ignition on before driving ***