Di2 Hydraulic road lever hydraulic issue
04-04-16, 11:41 PM
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Di2 Hydraulic road lever hydraulic issue
Has anyone seen a Shimano Di2 ST R785 lever that has lost hydraulic action. I replaced the brake hose and rebleed the system. The lever functioned correct for about a year then after a airplane flight it no longer has hydraulic function. I am not sure there is anything serviceable inside the lever. Any ideas other then replacement?
04-05-16, 01:04 PM
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Loss of brake pressure usually means that you need to fill and bleed the brakes.
It's possible that an airplane ride would cause the brake pressure to bleed out. The luggage compartments of jets are un-pressurized, so that's a huge pressure differential for the lightweight hydraulic system to deal with.
There are bleed kits available for home use. Or, take it to your local bike shop for a bleed.
It's possible that an airplane ride would cause the brake pressure to bleed out. The luggage compartments of jets are un-pressurized, so that's a huge pressure differential for the lightweight hydraulic system to deal with.
There are bleed kits available for home use. Or, take it to your local bike shop for a bleed.
04-05-16, 09:38 PM
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Not much to go on, but look for mechanical damage, leaks, etc.
Airliner baggage holds are pressurized same as the passenger cabin, typically no more than 0.3 bar differential w.r.t. sea level pressure. Not much compared to hydraulic pressure.
Airliner baggage holds are pressurized same as the passenger cabin, typically no more than 0.3 bar differential w.r.t. sea level pressure. Not much compared to hydraulic pressure.
Last edited by AnkleWork; 04-05-16 at 09:45 PM.
04-05-16, 10:09 PM
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It's possible that prolonged time not upright, possibly made worse by the drop in surrounding air pressure and caused the system to leak, or allowed an air bubble to accumulate within the lever's piston area.
Essentially, you would have a pump that needs priming, so will have from zero to minimal action.
You need to to a complete fill and bleed procedure, and hopefully the user guide will tell you how. On some systems, you use the fill port, while pumping the lever and leaving the brake end where oil can flow into a capture bottle. Pumping against no load allows the pump to self prime.
However, don't do anything until you learn the specific remedy for your brake.
Essentially, you would have a pump that needs priming, so will have from zero to minimal action.
You need to to a complete fill and bleed procedure, and hopefully the user guide will tell you how. On some systems, you use the fill port, while pumping the lever and leaving the brake end where oil can flow into a capture bottle. Pumping against no load allows the pump to self prime.
However, don't do anything until you learn the specific remedy for your brake.
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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.
