ST -8070 - Hydraulic Leak?
A number of (perhaps unrelated) issues that I'm trying to get to the bottom of.
1. Hung the bike upside down to store for the winter and had no brakes when I took it down after the winter. Mechanic reckoned it was air bubbles in the system, bled it and sorted.
2. Transported the bike in the boot of the car at the weekend lying flat (loaded the night before, so 12 hours on its side). No rear brakes when I took it out of the car in the morning.
3. Modulation has always been "long" since the bike was built. I'd say 2/3 of the pull before the brakes engage.
4. Fiddled with the lever free stroke adjustment this morning and noticed that if I pump the brakes the modulation reduces (ie brakes engage at 1/2 pull or less).
Any thoughts?
PS - pads are in good condition and there are definitely no leaks at the caliper end. Shifter internals looked "shiney" when I pulled the hood back, but can't tell if thats just from the bleed process that the mechanic carried out in May.
Comments
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Clean up the shifter and see if it looks shiny again in the future. It shouldn't if there is no liquid getting on it. Ask the mechanic if they wiped everything up after they bled the brakes.0
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If I’m reading this correctly,
"both brakes didn’t work > LBS mechanic bled both brakes in May and the problem appeared to be fixed.
In August the rear brake failed to operate at all, the front brake remained good."
I think it could be one of three things, a)leak b)air c)memory
First of all determine if you have a hydraulic fluid leak. Clean the ‘shiny’ area as best you can with alcohol/soapy water, whatever you have and then dry it, use a hair-dryer if necessary. Then tie the rear brake lever down in the on-position quite firmly but don’t go mad. Leave overnight, next day insect for leaks and take appropriate action if found.
No leaks, undo the brake and give it a try, has the braking improved? I suspect it will have, but it may not last, see how it goes. You might have to remove a pocket of stubborn air from the system with a careful bleed. Hopefully your woes will end here.
If after you’ve bled the system carefully and you’re sure there are no more tiny bits of air trapped within the pipework/caliper/lever and you still have a long lever pull before the brake engages, you’re going to have to ‘overfill’ slightly. If you get this far, come back and I’ll explain some more.0 -
What Charlie says. Additionally, it can help bleeding the back brake with the front end of the bike raised above level - to get an uphill run from the rear caliper to the lever.
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Many thanks guys. Will follows Charlie's instructions and feedback.0
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Quick question Charlie - the tied back brake lever step. Previous issues have manifested when storing bike on side or upside down. Should I set the bike on its side again during this step?Charlie_Croker said:If I’m reading this correctly,
"both brakes didn’t work > LBS mechanic bled both brakes in May and the problem appeared to be fixed.
In August the rear brake failed to operate at all, the front brake remained good."
I think it could be one of three things, a)leak b)air c)memory
First of all determine if you have a hydraulic fluid leak. Clean the ‘shiny’ area as best you can with alcohol/soapy water, whatever you have and then dry it, use a hair-dryer if necessary. Then tie the rear brake lever down in the on-position quite firmly but don’t go mad. Leave overnight, next day insect for leaks and take appropriate action if found.
No leaks, undo the brake and give it a try, has the braking improved? I suspect it will have, but it may not last, see how it goes. You might have to remove a pocket of stubborn air from the system with a careful bleed. Hopefully your woes will end here.
If after you’ve bled the system carefully and you’re sure there are no more tiny bits of air trapped within the pipework/caliper/lever and you still have a long lever pull before the brake engages, you’re going to have to ‘overfill’ slightly. If you get this far, come back and I’ll explain some more.0 -
ajkerr73 said:
Quick question Charlie - the tied back brake lever step. Previous issues have manifested when storing bike on side or upside down. Should I set the bike on its side again during this step?Charlie_Croker said:If I’m reading this correctly,
"both brakes didn’t work > LBS mechanic bled both brakes in May and the problem appeared to be fixed.
In August the rear brake failed to operate at all, the front brake remained good."
I think it could be one of three things, a)leak b)air c)memory
First of all determine if you have a hydraulic fluid leak. Clean the ‘shiny’ area as best you can with alcohol/soapy water, whatever you have and then dry it, use a hair-dryer if necessary. Then tie the rear brake lever down in the on-position quite firmly but don’t go mad. Leave overnight, next day insect for leaks and take appropriate action if found.
No leaks, undo the brake and give it a try, has the braking improved? I suspect it will have, but it may not last, see how it goes. You might have to remove a pocket of stubborn air from the system with a careful bleed. Hopefully your woes will end here.
If after you’ve bled the system carefully and you’re sure there are no more tiny bits of air trapped within the pipework/caliper/lever and you still have a long lever pull before the brake engages, you’re going to have to ‘overfill’ slightly. If you get this far, come back and I’ll explain some more.
I see no need to do that, I'd put the brake lever at the highest point (bike stood on the back wheel at about a 45° angle) if there is air in the system it should migrate to the highest point, making it easier to bleed. But check for leaks before removing the strap/binding0
