If there are burrs, deep scratches and other defects on the working surface of the disc that increase pad wear and reduce braking efficiency, as well as in the case of increased lateral runout of the disc that causes vibrations during braking, replace the disc. In specialized workshops, such a disc can be turned and ground on both sides to the same depth, but after processing, the thickness of the disc must not be less than the minimum permissible.
The minimum permissible thickness of the brake disc of the front wheel brake mechanism is 26 mm. If the thickness of one of the discs is less than the specified value, replace both discs. When replacing the brake discs, be sure to replace the brake pads with a new set.
1. Remove the wheel from the side of the disc being replaced.
2. Remove the caliper assembly (see Replacing the front brake caliper), without disconnecting the brake hose, and secure it with wire. Do not allow the hose to twist or stretch.
3. Using a screwdriver, remove the two retaining spring washers from the studs…
4….and remove the brake disc.
5. Similarly, remove the brake disc of the second brake mechanism.
6. Install the parts in the reverse order of removal.
NOTE: Before installing the disc, thoroughly clean the mating surfaces of the hub and disc from rust and scale, since even the smallest particle clamped between the mating surfaces will cause disc beating and vibration during braking.
NOTE: If you are installing the same disc, use a file to remove any ridges on the working surfaces of the disc that have formed as a result of disc wear on both sides.