Inspection
1. Loosen the wheel nuts and raise the vehicle on stands. Remove the wheels and install two lug nuts with 3mm washers to hold the disc in place. Release the parking brake when inspecting the rear brake.
2. Remove the caliper (see Section 3). There is no need to disconnect the brake hoses. Secure the calipers away from the work area. Remove the two bolts securing the guide to the steering knuckle (see fig. 4.2a) or, on rear brakes, to the trunnion bracket (see fig. 4.26). remove that bracket.
Fig. 4.2a Bolts for fastening the bracket to the steering knuckle
Fig. 4.2b Bolts for fastening the bracket to the rear wheel axle
3. Inspect the disc for nicks and damage. Light scratches and shallow grooves are not a cause for concern. If grooves or scratches are deeper than 0.4 mm, the disc surface needs to be restored. Inspect both sides of the disc.
4. If pulsations in the brake force occur during braking, check the disc runout by placing the indicator leg approximately 13 mm from the outer edge of the disc (see fig. 4.4a) Set the indicator to zero and spin the disc. The runout should not exceed the values given in the specification.
Fig. 4.4a Measuring the disc runout with an indicator
Fig. 4.4b Preparing the disk surface for measurement
Note: To eliminate the influence of disk unevenness when measuring runout, smooth out the marks with sandpaper, making circular movements (see fig. 4.4b).
5. The surface of the disc can be turned only up to certain limits: the minimum thickness of the disc is punched on its rim.
Fig. 4.5 Indication of the minimum disc thickness
Removal
6. Unscrew the retaining nuts (or retaining screws, see design) and remove the disk from the hub. If the disk does not come off, screw two bolts into the special threaded holes and remove the disk.
Fig. 4.6 Removing the disc using threaded holes
Installation
7. Place the disc on the studs.
8. Install the pad guide and caliper. Tighten the guide to the torque specified in the specification.
9. Lower the car, installing the wheels first. Press the brake pedal several times to install the pads in place. Bleed the brake system, if necessary.