Is this common on disc brakes?
10-02-22, 11:47 PM
#1
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Is this common on disc brakes?
I was bleeding the hydraulic disc brakes for Shimano BR-MT520. I placed the block in the calipers, pulled the lever and after half a second the pressure released then the caliper started leaking fluid. I know it can happen that a seal or piston will wear down, but there is only a few thousand kms on this bike.
Did I do something wrong?
Did I do something wrong?
10-03-22, 09:22 AM
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If you used the yellow bleed block there shouldn't be any way this could happen. You had the pads out of the caliper and used a yellow block? Or...?
10-03-22, 04:57 PM
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Did they leak when you're just riding the bike?
10-03-22, 10:07 PM
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Where exactly...and I mean exactly...was the leak?
10-03-22, 10:09 PM
#7
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They worked fine before, pistons were pushed back with with a plastic tire lever. I took the calipers apart and found when I pushed the leaking piston in, there was a crunching sound.
I guess with the lack of answers that this may have just been a fluke. Well, the replacement calipers arrive today. Hope it goes well
I guess with the lack of answers that this may have just been a fluke. Well, the replacement calipers arrive today. Hope it goes well
10-03-22, 10:43 PM
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I suspect that when you somehow pushed the pads out farther than normal, the seal picked up some dirt sitting outside it's normal working range, and then dragged it back where it interfered with the seal.
Since you're ready to declare these dead and have a replacement on the way, it's time for an autopsy. Take the brake apart, see if you can figure out what happened, and who knows, you might even be able to fix it, and have a spare. The worst that happen is that you learn something.
Since you're ready to declare these dead and have a replacement on the way, it's time for an autopsy. Take the brake apart, see if you can figure out what happened, and who knows, you might even be able to fix it, and have a spare. The worst that happen is that you learn something.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
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10-04-22, 10:50 AM
#9
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My best guess, is the block was not long enough. (Yes, a chinese clone, not original Shimano) This is a 4 piston caliper and even though the block was in place with the pin, I'm afraid it may have moved so half a piston was not "blocked" so when hydraulic pressure applied, the piston came out tilted, thus shattering the ceramic.
Live and learn. The caliper was not stupidly expensive, so a costly lesson.
Thanks for the input, hopefully my error will aid others in the future
Live and learn. The caliper was not stupidly expensive, so a costly lesson.
Thanks for the input, hopefully my error will aid others in the future
10-04-22, 03:48 PM
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They worked fine before, pistons were pushed back with with a plastic tire lever. I took the calipers apart and found when I pushed the leaking piston in, there was a crunching sound.
I guess with the lack of answers that this may have just been a fluke. Well, the replacement calipers arrive today. Hope it goes well
I guess with the lack of answers that this may have just been a fluke. Well, the replacement calipers arrive today. Hope it goes well
