Rear Deore hydraulic brake not working
thistle_
Posts: 7,218
I've had a set of Deore brakes for years now. The front one is fine, no problems, never even bled the thing.
The rear was fine when I first got it but over the last 12 months or so it's just not been working properly to the point that it hardly does anything.
Braking performance is poor so I swapped the pads bedded them in and it was great until the next time I took the bike out and it barely worked again.
The lever now pulls all the way back to the handlebar, the pistons move but don't seem to apply enough force to make the brake work - I can stop with the brake but it takes 50m or so.
I have bled the brake twice, and each time the lever is really firm when I've done it but then the next time I go for a ride it pulls all the way back to the bars.
If I pump the lever it does get more firm, but the braking performance doesn't improve much.
I'm suspecting a leak somewhere however there's signs of oil leaking at the caliper or at the lever, or there is a huge amount of air in the system somewhere. When I bleed the brakes, the fluid that comes out isn't discolored and no bubbles come out, it's still nice and pink.
Apart from trying flushing out the old oil and replacing with new (or buying new brakes) does anyone have any other suggestions for things to try?
I have the bleed kit from Epic, which uses a syringe without a plunger on the lever (rather than a funnel). Should I try bleeding them like I would with Avids - using the syringe on the lever to to suck any air out?
The rear was fine when I first got it but over the last 12 months or so it's just not been working properly to the point that it hardly does anything.
Braking performance is poor so I swapped the pads bedded them in and it was great until the next time I took the bike out and it barely worked again.
The lever now pulls all the way back to the handlebar, the pistons move but don't seem to apply enough force to make the brake work - I can stop with the brake but it takes 50m or so.
I have bled the brake twice, and each time the lever is really firm when I've done it but then the next time I go for a ride it pulls all the way back to the bars.
If I pump the lever it does get more firm, but the braking performance doesn't improve much.
I'm suspecting a leak somewhere however there's signs of oil leaking at the caliper or at the lever, or there is a huge amount of air in the system somewhere. When I bleed the brakes, the fluid that comes out isn't discolored and no bubbles come out, it's still nice and pink.
Apart from trying flushing out the old oil and replacing with new (or buying new brakes) does anyone have any other suggestions for things to try?
I have the bleed kit from Epic, which uses a syringe without a plunger on the lever (rather than a funnel). Should I try bleeding them like I would with Avids - using the syringe on the lever to to suck any air out?
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Comments
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When bleeding, did you go through the tilting the lever routine at the end? This can purge trapped air out of the lever.
IIRC though, older Deores have a different bleed procedure - which ones do you have?0 -
Pretty sure mine are the newer ones, the ones that require the threaded funnel (or if using the kit from Epic the syringe with the threaded end).
I turn the lever horizontal after bleeding it at 45 degrees, then repeat as per the instructions so I think I'm doing it correctly.0 -
Sounds like there is either a leak, or problem with the diaphragm. Either way for one that's seen service for many years, the most pragmatic answer is probably just replace the lever and olive, or even the complete brake rather than muck about with it.0
