Maintenance - Major Service

14-1. Check and renew the brake fluid (disc brakes - front and rear)

The hydraulic brake requires no regular adjustments; pad wear is compensated for by the automatic entry of more fluid into the system from the fluid reservoir. All that is necessary is to maintain a regular check on the fluid level and the degree of pad wear. To check the fluid level, turn the handlebars until the reservoir is horizontal (front brake only) and check that the fluid level, as seen through the reservoir body, is not below the lower level mark. Remember that while the fluid level will fail steadily as the pad friction material is used up, if the level falls below the lower level mark there is a risk of air entering the system; it is therefore sufficient to maintain the fluid level above the lower level mark, by topping-up if necessary. Do not top up to the higher level mark unless this is necessary after new pads have been fitted. If topping up is necessary, wipe any dirt off the reservoir, remove the retaining screws and lift away the reservoir cover or unscrew the cap, as appropriate, and withdraw the diaphragm. Use only good quality brake fluid of the recommended type and ensure that it comes from a freshly opened sealed container, brake fluid is hygroscopic, which means that it absorbs moisture from the air, therefore old fluid may have become contaminated to such an extent that its boiling point has been lowered to an unsafe level. Remember also that brake fluid is an excellent paint stripper end will attack plastic components; wash away any spilled fluid immediately with copious quantities of water. When the level is correct, clean and dry the diaphragm, fold it into its compressed state and fit it to the reservoir. Refit the reservoir cover or cap (and gasket, where fitted) and tighten securely, but do not over tighten, the retaining screws (where appropriate).

Brake fluid renewal

Note that hydraulic brake fluid must be changed annually. It is necessary to renew the brake fluid at this interval to preserve maximum brake efficiency by ensuring that the fluid has not been contaminated and deteriorated to an unsafe degree.
Before starting work, obtain a new, full can of the specified hydraulic fluid and read carefully the Section on brake bleeding in Chapter 9 - Wheels & Brakes. Prepare the clear plastic tube end glass jar in the same way as for bleeding the hydraulic system, open each bleed nipple by unscrewing it 11/4 - 1/2 turn with a spanner and apply the front brake lever or rear brake pedal (as applicable) gently and repeatedly. This will pump out the old fluid. Keep the master cylinder reservoir topped up at all times, otherwise air may enter the system and greatly lengthen the operation. The old brake fluid is invariably much darker in color than the new, making it easier to see when it is pumped out and the new fluid has completely replaced it. Note that the manufacturer recommends that in order to ensure the complete replacement of the old brake fluid, it will first be necessary to remove the brake pads and to push the caliper pistons back as far as possible into the caliper body. Where more than one bleed nipple is fitted to a system (eg the front brake) repeat the operation on both nipples to ensure that the old fluid is completely removed. Top up the master cylinder when the operation is complete.

Brake hydraulic fluid level must be maintained above minimum level mark

Use good quality fluid from a sealed container when topping up

Ensure diaphragm is clean and dry before refitting