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  1. #1
    stay thirsty, my friends
    Reputation: LBmtb's Avatar
    Join Date
    Jul 2004

    hfx9 - how to drain some fluid?

    I've heard that sometimes there could be too much brake fluid in the HFX-9 (hayes). Has anyone talked to a hayes tech who told them how to drain the excess fluid?

    Think that's my next step in figuring out how to stop my brakes rubbing.
    "With that said, until you have done a STR group ride- YOU HAVE NOT LIVED!"
    - dino brown

  2. #2
    Race Technician
    Reputation: Randy@Hayes's Avatar
    Join Date
    Jan 2005

    Here's how....

    Yes a brake can be overfilled. It usually happens when the pistons are not fully retracted prior to a bleed.

    To release the extra fluid, loosen the lever and flip it straight up so the flat area with the reservoir plug is horizontal with the ground. Connect a catch bottle ( our bleed kit comes with the correct mating fitting) or be ready to clean up after with alcohol. Remove the wheel, remove the brake pads. I find it easier to remove the caliper from the mount and hold it in my hand to push the pistons back. I use a 12 or 13mm box end wrench to push the pistons back. Insert the box end over the piston and push the piston back till it's flush with the caliper bore being careful not to bend or break the piston post. If you lever the wrench against the oposite side of the caliper to push the piston back you will probably push the piston in crooked which will cause the pad not to sit flush in the bore which can cause pad rubbing. Once both side are pushed back, anyfluid that come out is extra.

    Cap the reservoir, clean the mess if any, wash your hands.

    One thing I do to pads to make them fit tighter on the piston is to crimp the pad spring where it comes over the backing plate of the pad. This will increase the spring tension.

    Replace the pads, remount the caliper, squeeze the lever a few times, align the caliper and you're good to go. Ride it a while and recheck the caliper alignment.

    Hope this helps,

    Hayes Disc Brakes

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