Maintenance - Major Service

14-2. Check and renew the brake pads (disc brakes - front and rear)

To check the degree of pad wear, prise the plastic cover off each caliper body and assess the amount of friction material remaining on each pad; if either is worn at any point so that the metal backing is approaching contact with the disc, both pads must be renewed immediately. If the pads are so fouled with dirt that the friction material cannot be distinguished, or if oil or grease is seen on them, they must be removed for cleaning and examination. Unclip the plastic cover from the caliper and use a suitable drift to tap out the two pad retaining pins from the inside outwards; take care not to allow the retaining spring to fly off. Remove the central pin and withdraw both pads. If the pads are worn to a thickness of 1.5 mm (0.06 in) or less at any point, fouled with oil or grease, or heavily scored or damaged by dirt and debris, they must be renewed as a set; there is no satisfactory way of degreasing friction material. If the pads can be used again, clean them carefully using a fine wire brush that is completely free of oil or grease. Remove all traces of road dirt and corrosion, then use a pointed instrument to dig out any embedded particles of foreign matter. Any areas of glazing may be removed using emery cloth. On reassembly, if new pads are to be fitted, the caliper pistons must now be pushed back as far as possible into the caliper bores to provide the clearance necessary to accommodate the unworn pads. It should be possible to do this with hand pressure only. If any undue stiffness is encountered the caliper assembly should be dismantled for examination as described in Chapter 9 - Wheels & Brakes

While pushing the pistons back, maintain a careful watch on the fluid level in the reservoir. If the reservoir has been overfilled, the surplus fluid will prevent the pistons returning fully and must be removed by soaking it up with a clean cloth. Take care to prevent fluid spillage. Apply a thin smear of caliper grease to the pad retaining pins. Take care to apply caliper grease to the metal backing of the pad only and not to allow grease to contaminate the friction material. Carefully fit the pads to the caliper and hold them in place while the first retaining pin (with the spring looped over it) is refitted. Place a central pin in the pad cutouts and press the spring over it and underneath the second retaining pin which should now be pressed into place. Refit the plastic cover. Apply the brake lever gently and repeatedly to bring the pads firmly into contact with the disc until full brake pressure is restored. Be careful to watch the fluid level in the reservoir; if the pads have been re-used it will suffice to keep the level above the lower level mark, by topping-up if necessary, but if new pads have been fitted the level must be restored to the upper level line described above by topping-up or removing surplus fluid as necessary. Refit the reservoir cover or cap, gasket (where fitted) and diaphragm as described above. Before taking the machine out on the road, be careful to check for fluid leaks from the system, and that the front brake is working correctly. Remember also that new pads, and to a lesser extent, cleaned pads will require a bedding-in period before they will function at peak efficiency. Where new pads are fitted use the brake gently but firmly for the first 50 - 100 miles to enable the pads to bed in fully.


Prise plastic cover off caliper body to check brake pads


Use hammer and a long drift to tap out pad retaining pins from behind caliper


Remove pads, noting which way round each is fitted - check for uneven wear


Pads must be renewed as a set if any is worn to service limit or less


Ensure friction material is against disc when refitting brake pads ......


insert first retaining pin with spring, then refit central pin, as shown ......


..... and tap second retaining pin into place, over spring end