IG.
Registered
So, on Saturday, the day before the Sunday ride, I decided it was time to clean my calipers for the first time ever, since my front wheel was out. Removed one of them from the fork, removed the pads. Pumping the brake lever to extend the pistons. Only one of the pistons is moving out. So, I am thinking well it's gonna stop at some point, right? Wrong - one of the pistons just falls out and the brake fluid is leaking. And you know what this means. Cursing myself, I realize what happened. I realize that I need to have at least the pads installed to make sure no piston pops out.
So, I said to myself, don't panic. All you need to do is put the piston back and bleed the system. Otherwise, the bore looks nice and clean, and the part of the piston which goes inside also looks nice and clean. I notice that the dust seal is partially out. So, I carefully stick it back. Then had enough sense to cover the piston in brake fluid and carefully push it inside. After some time, I succeed and the piston is in. Luckily, I had a new bottle of brake fluid. I use Mighty Vac to bleed the fluid, check the lever - mushy - still got air in the system. So, I switch to the basic method of press and hold the lever, and playing with the bleed screw - my wife helps me with this. I have to tell you that this basic method does get rid of the air trapped inside the caliper. The lever became really hard when squeezing. Great! Now, all I need to know there is no leak at the piston. I try a few more times to squeeze and push the piston out and then push it back. It goes back easy and smooth and there is no leak - whew! Quck cleaning with water and soap, and both calipers are done. A quick test ride confirms I am OK. What a way to spend most of your Saturday!
Now, to the question. Besides the piston which popped out, most others are pretty hard to push back by hand. Also, when I sqeeze the lever most of the pistons are hard to come out. Observing the pads wear, I notice that the further away the piston is from the incoming brake line, the less wear the pad has - which is consistent with my observation of how hard it is to push the pistons back. I tried to move them all out and push them back a few times, and thought it will improve the ease of their movement, but this wasn't the case.
So, what makes the pistons hard to move?
Another thought I had, that maybe I just need to push the pistons out and lubricate them with brake fluid prior to pushing them in, doing it a few times, and this should make the pistons come out/be pushed in easier. Any thoughts on that? Keep in mind, I pushed out all pistons about 1/2" and aside from their very top portion, they all look clean and shiny.
So, I said to myself, don't panic. All you need to do is put the piston back and bleed the system. Otherwise, the bore looks nice and clean, and the part of the piston which goes inside also looks nice and clean. I notice that the dust seal is partially out. So, I carefully stick it back. Then had enough sense to cover the piston in brake fluid and carefully push it inside. After some time, I succeed and the piston is in. Luckily, I had a new bottle of brake fluid. I use Mighty Vac to bleed the fluid, check the lever - mushy - still got air in the system. So, I switch to the basic method of press and hold the lever, and playing with the bleed screw - my wife helps me with this. I have to tell you that this basic method does get rid of the air trapped inside the caliper. The lever became really hard when squeezing. Great! Now, all I need to know there is no leak at the piston. I try a few more times to squeeze and push the piston out and then push it back. It goes back easy and smooth and there is no leak - whew! Quck cleaning with water and soap, and both calipers are done. A quick test ride confirms I am OK. What a way to spend most of your Saturday!
Now, to the question. Besides the piston which popped out, most others are pretty hard to push back by hand. Also, when I sqeeze the lever most of the pistons are hard to come out. Observing the pads wear, I notice that the further away the piston is from the incoming brake line, the less wear the pad has - which is consistent with my observation of how hard it is to push the pistons back. I tried to move them all out and push them back a few times, and thought it will improve the ease of their movement, but this wasn't the case.
So, what makes the pistons hard to move?
Another thought I had, that maybe I just need to push the pistons out and lubricate them with brake fluid prior to pushing them in, doing it a few times, and this should make the pistons come out/be pushed in easier. Any thoughts on that? Keep in mind, I pushed out all pistons about 1/2" and aside from their very top portion, they all look clean and shiny.