Pumping the lever will expose one piston slightly. Do not pump
too much, as the piston can be pushed out too far. Three to five
millimeters exposed should be perfect for most brakes.
With the one piston now exposed, it’s time to clean the surfaces
that seal the brake from brake dust, dirt, grime and debris.
Use the spray bottle of isopropyl alcohol to wet the Q-tip, and
liberally spray down the caliper and pistons.
Use the Q-tip to scrub the outside of the piston surface. Putting
the alcohol in a spray bottle makes this easier, but just dipping the
Q-tip in works well too.
With the inside and outside of the brake now clean, it’s time to
lubricate the piston surface. With Shimano brakes, you should use
Shimano-brand mineral oil. Just a couple of drops applied directly
on the exposed piston is perfect. Never use any lubricant that’s
not specified by the manufacturer for this. Shimano recommends
using a few drops of their mineral oil, while other manufacturers
recommend continuing to move the pistons and allowing the
system to lubricate itself. Using lubricants other than those
specified, such as chain lube or fork oil, will cause seal problems,
pad contamination and a host of other problems
Use the plastic tire
lever to push the clean
piston back into place.
Sometimes, using the
body of the caliper for
leverage with the tire
lever can be useful.
Then, repeat with the
Extract the piston using
the tire lever and pumping process, then clean
with a fresh isopro-pyl-soaked Q-tip.
Once cleaned and
lubed, check to see
that the pistons are
by pumping the
brakes one to two
times without the
pads, wheel or rotor
in. If they look like
this, with an equal
amount of piston
showing after the
couple of pumps,
you’re ready to
Spray a clean paper towel with isopropyl
alcohol to clean the brake. Many shop
rags can be contaminated with oils, even
if they have been washed, so a paper
towel is best for this job.
Use the paper
towel to thoroughly
clean all the surfaces of the brake. We
prefer this handy
“flossing” technique for cleaning
the inside of the
brake, which is likely coated with the
lubricating oil you