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I have an 8-year-old old Avid Juicy 3 and I accidentally pressed the front brake lever while the wheel was removed. I used a flat-head screwdriver to reset the pistons. When I spin the wheel after resetting, it works fine, but when I press the lever it doesn't retract and it rubs against the disk. I thought the oil pressure was the problem and I let some oil out of the system.

  • Is this because of the dirty pistons?
  • is it okay that I let some oil out? (Few drops of oil)

Plus the Avid Juicy 3's piston looks weird and I don't know how to clean it. It's shaped like a cone... (Plus plus, i don't know what kind of DOT fluid my brake uses –it's green.)

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  • Hello an welcome to the site! Have you tried looking for service manuals for the brakes? Letting oil out was not a clever thing, in my opinion, because 1) everything worked just fine with original amount of oil before 2) oil does NOT have its "own" pressure as it is with e.g. air, because the liquid is practically incompressible, 3) by opening hydraulic lines you have likely let some air into the system, to restore brakes functioning, you will have to "bleed" the brakes now. – Grigory Rechistov Jan 12 at 11:19
  • well, that's depressing.. i really didn't want to bleed my brakes..anyways thank you! – yeongmin jo Jan 13 at 2:44
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You absolutely should not have let fluid out of the system. If the brake was working before there was not too much fluid in the system. You will need to bleed the brake to remove air bubbles and restore the fluid level. (If the back brake has not been bled in eight years you should do that one too.) Dirty pistons and seals are usually to blame for non-retracting pistons. In extreme cases the whole caliper has to be disassembled and cleaned.

You can try to find the manual for Avid brakes by searching on the SRAM website. There is a 2006 manual which may apply.

Check out this Park Tool video for how to clean hydraulic brake calipers. It also explains how piston retraction and advancement works.

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  • when i was letting my fluid out of the brakes i just opened the valve just a tiny bit (i didn't remove the valve, just unscrewed it 2 times) and i crossed my fingers that there won't be any air entering the system. And avid brake's piston looks different compared to other pistons in this(above) video. (ps. My rear brakes are working fine but do i need to bleed that as well? and how often should i bleed my bike?) – yeongmin jo Jan 13 at 2:52
  • @yeongminjo More often that every 8 years, that's for sure! I think SRAM recommends either every year or two years for their road hydraulic brakes (which is what I have). The DOT fluid absorbs water and needs to be refreshed. – Argenti Apparatus Jan 13 at 3:07

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