Front Brakes Won't Bleed
#11
07-24-2024, 04:40 AM
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That's what makes me think it may be caliper seals: You say you can bleed the brakes and get a firm lever, but then when you move the bike, the lever will come back all the way in again. So you must be getting all the air out of the system to get a firm lever. So then when you move the bike, the caliper seals are either pulling the pistons back away from the disk, or letting air bleed in. You might, maybe, if you are lucky, try pulling the pads out, then pumping the pistons way out past their normal position and try cleaning the pistons in the area where the seals normally sit. Then apply a little silicon grease around the pistons and inside the outer dust boot and push them all the way back in again and reinstall the pads. Sometimes you get lucky.
The other thing is with DOT 5 brake fluid, don't shake the bottle. That stuff is as thick as molasses, almost, and once it gets bubbles in it, takes forever for them to rise up and out of the fluid. Hence advice above to bleed slowly. That stuff moves slow. That is one reason they dont use it on the ABS bikes. And if it gets lots of small bubbles in it, they sit there for a long time before they join up into a bigger bubble that you can bleed out.
Unless you have a loose bearing or spacer that allows the disk to push the pistons back into the caliper and cause a loose lever again. But you said you don't have that so that pretty much leaves the caliper as the source, if you are bleeding right as per Twizted's description.
The other thing is with DOT 5 brake fluid, don't shake the bottle. That stuff is as thick as molasses, almost, and once it gets bubbles in it, takes forever for them to rise up and out of the fluid. Hence advice above to bleed slowly. That stuff moves slow. That is one reason they dont use it on the ABS bikes. And if it gets lots of small bubbles in it, they sit there for a long time before they join up into a bigger bubble that you can bleed out.
Unless you have a loose bearing or spacer that allows the disk to push the pistons back into the caliper and cause a loose lever again. But you said you don't have that so that pretty much leaves the caliper as the source, if you are bleeding right as per Twizted's description.
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#12
07-24-2024, 04:47 AM
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#13
07-24-2024, 06:07 AM
That's what makes me think it may be caliper seals: You say you can bleed the brakes and get a firm lever, but then when you move the bike, the lever will come back all the way in again. So you must be getting all the air out of the system to get a firm lever. So then when you move the bike, the caliper seals are either pulling the pistons back away from the disk, or letting air bleed in. You might, maybe, if you are lucky, try pulling the pads out, then pumping the pistons way out past their normal position and try cleaning the pistons in the area where the seals normally sit. Then apply a little silicon grease around the pistons and inside the outer dust boot and push them all the way back in again and reinstall the pads. Sometimes you get lucky.
The other thing is with DOT 5 brake fluid, don't shake the bottle. That stuff is as thick as molasses, almost, and once it gets bubbles in it, takes forever for them to rise up and out of the fluid. Hence advice above to bleed slowly. That stuff moves slow. That is one reason they dont use it on the ABS bikes. And if it gets lots of small bubbles in it, they sit there for a long time before they join up into a bigger bubble that you can bleed out.
Unless you have a loose bearing or spacer that allows the disk to push the pistons back into the caliper and cause a loose lever again. But you said you don't have that so that pretty much leaves the caliper as the source, if you are bleeding right as per Twizted's description.
The other thing is with DOT 5 brake fluid, don't shake the bottle. That stuff is as thick as molasses, almost, and once it gets bubbles in it, takes forever for them to rise up and out of the fluid. Hence advice above to bleed slowly. That stuff moves slow. That is one reason they dont use it on the ABS bikes. And if it gets lots of small bubbles in it, they sit there for a long time before they join up into a bigger bubble that you can bleed out.
Unless you have a loose bearing or spacer that allows the disk to push the pistons back into the caliper and cause a loose lever again. But you said you don't have that so that pretty much leaves the caliper as the source, if you are bleeding right as per Twizted's description.
Thanks.
#15
07-24-2024, 06:27 AM
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#16
07-24-2024, 11:07 AM
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#17
07-24-2024, 01:06 PM
Yet another reason I bought a used Coates tire machine and some new plastic lever protectors (though after handling them I now could make spares with a milk jug and heat gun). BTW tire mounting compound is glorious so no more Dawn and water for me.
#18
07-24-2024, 02:29 PM
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Last edited by Uncle Larry; 07-24-2024 at 05:23 PM.
#19
07-24-2024, 03:34 PM
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#20
07-24-2024, 05:09 PM
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