Keep your brakes working well
Top tips to ensure your bike’s stoppers perform perfectly
1 Clean up your act
Brake calipers require regular cleaning and maintenance to keep them performing at their best. The main body of the caliper, the pistons and the bore in which they slide should be cleaned often. Serviceable parts such as the dust and fluid seals and O-rings that seal the two halves of the caliper should be replaced using genuine parts at recommended intervals.
2 Remove the pads
Remove the brake pads, making a note as you go of how they are retained as quite often there is a pin that goes through the pad as well as a sprung anti-rattle shim. If you are re-using the same pads after cleaning it is good practice to make a note of which side of the caliper each was originally fitted to and return them to the same side.
3 Pre-clean the calipers
Wear gloves and beware spilling brake fluid as you remove the calipers Remove the brake calipers from your bike by undoing and removing the caliper bolts and disconnecting the brake hose(s) and all connectors. Before splitting the caliper in half, give it a clean with bike cleaner and a brush. The idea is to remove the heavy deposits of road dirt and dust. Soak it with cleaner, agitate the dirt until it yields, then rinse off with water. No airline? Buy a caliper removal tool from your local motoring shop
4 Pop out the pistons
The pistons will need to be removed for cleaning. The easy way to do this is to ease them out with an airline via the brake line port, but take care when doing this (see story, left). Use a relatively low pressure and place something like a spanner in the middle of the caliper to prevent the pistons popping out altogether. Then remove the bleed nipple.
5 Time to split
Put the caliper in a vice then undo the bolts that secure the two halves, making a note of which bolts go where if different lengths. Before splitting, keep an eye out for any O-rings located inside. These will be replaced anyway, but keep them to make sure that the new ones match.
6 Extract the pistons and seals
Remove the pistons from the caliper. The airline should have pushed them almost out so they’ll be easy to remove using a piston extractor. Beware: excessive force can damage the surface. Remove all the pistons then ease out the seals using a fine pick or very small flat-bladed screwdriver.
7 Clean up corrosion
Clean away any corrosion build-up from behind the seals and within the bore. This can be tricky and is best tackled using a small, fine wire brush or a Scotchbrite pad soaked in brake cleaner. The machined area where the two halves meet should be free of any contamination, but avoid scrubbing and causing damage to the mating surfaces.
8 Polish your pots
The brake pistons should be in good condition, although it’s usual for the top, exposed part to become dirty and tarnished. This can be cleaned up using Autosol (or similar) and you can also use a mop on a drill at low speed to help speed the process. Once the cleaner has been applied, switch to a buffing mop and finish off by polishing all over.
9 Seal of approval
Give the caliper a blast of brake cleaner then fit the new seals. There are two seals per piston. The dust seal is usually thinner and has a double lip. The other thicker seal is responsible for keeping the pressurised brake fluid contained in the caliper. Often this seal is subtly shaped and needs to be fitted correctly so consult your workshop manual.
10 Rebuild and refit
Push the pistons back into place until they bottom out. A very light smear of brake fluid on the lower seal is all that should be used to help them in. Then, with the new O-rings in place, join the two halves together and tighten up evenly. Use a torque wrench and tighten the bolts up to the correct spec. Replace the brake pads and retaining pins. Refit to bike.