Disc brake hydraulic system bleeding

Efficient braking, all things being equal, only comes from a well blei hydraulic system. Air in that system is a killer.

Air can enter the hydraulic system through a too low master cylinder fluid reservoir level, through leakage in component seals or when a component is dismantled. Brake bleeding, bleeds , that air out of the system.

Always use the highest grade of approved brake fluid available. Everyone knows the best brands. Never re-use fluid which has been used before and never undertake the task in a heavily water saturated atmosphere.

The details following apply to one caliper; for twin front discs, repeat the operation for the second caliper after you are satisfied the first one is bled.

Place a piece of transparent polythene tube over the outer bleed nipple once you have removed its rubber cap. Place the other end of the tube in a clean glass jar on the ground and submerge the end in clean brake fluid. Remove the fluid reservoir cap and the convoluted seal beneath it, and top the fluid level up using new fluid. Slacken the bleed nipple, about one full turn [a small ring spanner which you can leave on the nipple, 'under' the polythene tube works best). Then pull in the lever (or press the pedal) and let it go slowly, several times. Do both actions slowly.

Watch for fluid and air bubbles in the polythene tube. Keep this operation up until only 'solid' fluid passes through the polythene tube (make sure the reservor level is kept up during this operation). Once you have seen isolid' fluid pull the lever in (press the.pedal down) and tighten up the bleed nipple on the caliper. Let the lever (pedal) go. Now repeat the operation for the other nipple, and then top up the reservoir and replace the seal and cap. On twin disc fronts, bleed the other caliper, even if nothing specific has been attended to on the caliper. Throw the fluid collected in the glass jar away.

(Air can be trapped in the front divider and it becomes difficult to bleed through the calipers. Place the master cylinder below the divider and bleed the air 'up' through the master cylinder).

The right hand side rear disc bra* e pecu a»a master cylinder mechanism is es< ; se-« ze because it is more accessible

The drilled a:sc set-up on the liiniumwj 1200. The disc to tub bolts are locking taz: a ? -eac , visible

The SFC's rear disc brake pedal set-.: ocarafes very simply

The right hand side rear disc bra* e pecu a»a master cylinder mechanism is es< ; se-« ze because it is more accessible

The drilled a:sc set-up on the liiniumwj 1200. The disc to tub bolts are locking taz: a ? -eac , visible

The SFC's rear disc brake pedal set-.: ocarafes very simply

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