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So, I'm pretty religious about bleeding my brakes and cleaning up and so on, but I can't help but think after 46k miles that the calipers and master cylinder might need some kind of maintenance. To be honest, they brakes do feel kind of "old" these days. The smoothness that they once exhibited in the front just isn't there anymore. My EBC HH sintered pads have a long way to go, so they're fine.
So what should I do to refresh my calipers and master cylinder? should i do anything at all? is any maintenance needed to keep those parts running in top form?
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Hmm, I feel bad. Never replaced my calipers on any ride. Past master cylinder/reservoirs usually get very yellow in colour with the plastic cracking from sun bake. Sometimes I can't even read the hydraulic fluid level.
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He could remove the calipers and clean/hone the cylinders. Then reinstall the piston with a new seal.
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Things to look out for is corrosion, it happens mostly in three places; on the outside of the pistons, in between the two square rings ( their industrial name for square o-rings ) first one is a dust seal and the next one is the liquid seal, where some fluid comes in contact with air and react, the more corrosion in the grooves the more fluid escapes etc.
and at the back of the master cylinder under the soft rubber seal for the same reason, when left unchecked the corrosion can start to attack the master cylinder wall and produce pitting which produces more fluid to escape.
For that reason i apply some silicone grease, very sparingly in the grooves after cleaning the square rings, some advice to install the pistons with some brake fluid, i don't like that idea, it leaves the corrosive fluid around the seals, i think silicone grease is a much less corrosive method, and a bit more liberally at the back of the master cylinder in the space where the connecting pushrod sits.
As long as the square rings don't cause the brakes to drag i think they don't need replacement but it does no harm to do so as long as it is done correctly.
Personally i push the pistons back inside the calipers to expel as much old fluid as possible in the system before refreshing the brake fluid every two years, the calipers need a clean at least every year depending on conditions.
Pitting in the caliper cylinders ( apart from the grooves ) has no effect on the braking because the pistons are supported by the square rings and align themselves on the back of the brake pads, they never touch the cylinder walls, it is just cosmetic if they are pitted.
It seems more practical advice is coming your way, thanks for the question.
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This is all helpful. I've never had the calipers or master cylinder apart for any reason and the bike is 7 years old at this point....4 years in the road. If you're saying it's a good idea to at least clean out the calipers once annually then im certainly due for something and I may find the cause of my problems there.
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What Max said is true. Corrosion can cause the seal (that square one) to bind up some and prevent the normal piston retraction. Which isn’t really very much. I recommended changing the seals as they age, and you have everything apart anyway…
Max, I knew if I typed a brief post that you would expound on it!
Saves me typing LOL
