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  1. #1
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    Ok, I've bled a dozen Hayes brakes, but still have problems getting decent pressure

    Using the syringe method (back and forth until no bubbles, pump the lever with pressure on syringe, close the bleed screw with pressure on syringe), with pistons retracted, I get hardly any lever pressure at all. If I pump the pistons out quite a bit and then bleed I get a reasonable amount of lever pressure, but I'd like more. (Having to wind the lever adjustment screw all the way in just to make the brake work).
    What do others do to get a decent amount of pressure?

  2. #2
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    Are your pads worn?

    Quote Originally Posted by Haggis
    Using the syringe method (back and forth until no bubbles, pump the lever with pressure on syringe, close the bleed screw with pressure on syringe), with pistons retracted, I get hardly any lever pressure at all. If I pump the pistons out quite a bit and then bleed I get a reasonable amount of lever pressure, but I'd like more. (Having to wind the lever adjustment screw all the way in just to make the brake work).
    What do others do to get a decent amount of pressure?
    Are the brake pads worn down requiring the piston to extend further to compensate?

  3. #3
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    Quote Originally Posted by imridingmybike
    Are the brake pads worn down requiring the piston to extend further to compensate?
    Yes they are, but not hugely so. Anyway it's neither here nor there how worn the pads are. According to Hayes the pistons are supposed to be pushed fully back before bleeding...result: no pressure. Any Hayes guru's out there?

  4. #4
    the wrench
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    i have found after belleding hayes brakes sometimes shimano that there is hardly any lever pressure. because they are a closed system pumping them will somtimes work.NOTE:the faster you pump the better it will work (usualy)

    or dont pusk the pistoms back before bleeding because its always easier to let fluid out then bleed more back in.
    do it, do it DO IT!!
    DOOOO IIIIIT!!

  5. #5
    mtbr member
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    The way that worked best for me...

    i.e that produced the consistently good brakes is to inject from the bleed nipple.

    though this is on an XTR, so YMMV.

    fill up a large syringe( I do not remember the volume but it should be at about 2x the system volume. Hook syringe up at the bleed, Pump a few times at the lever to inject oil into the syringe and extending your pistons. You should then allow any air bubbles to float to the top of the syringe. Remove the cap from the levers and inject from the syringe displacing oil out the levers. You must keep the syringe upright all the time to prevent any air being injected, so the syringe piston should remain above the syringe pointy end.

    Inject the oil allowing the pistons to extend to their max. Close the bleed,reset the pistons, pop the lever caps back on and clean up the mess.

    You will spill a bit of oil at the levers but you know that you have flushed any possible air UP through the levers.



    Quote Originally Posted by Haggis
    Using the syringe method (back and forth until no bubbles, pump the lever with pressure on syringe, close the bleed screw with pressure on syringe), with pistons retracted, I get hardly any lever pressure at all. If I pump the pistons out quite a bit and then bleed I get a reasonable amount of lever pressure, but I'd like more. (Having to wind the lever adjustment screw all the way in just to make the brake work).
    What do others do to get a decent amount of pressure?

  6. #6
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    Sounds like you have you have the basics covered. Always push the fluid up using a syringe(60cc) Some tips that help me. Is the caliper bleed/hose in a vertical position, air can be trapped in the caliper. Also make sure the bleeder on the master is at the highest point.like 45 degree angle. Then stick that plastic nipple from the Hayes kit in the master with a hose in a small bottle of brake fluid and pump the lever, as you pump the lever air bubbles will go back an forth and finally into the bottle Hope this helps.
    -Ride

  7. #7
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    I'm wondering how much of a distance the pads are from the rotor face.

    I would try pumping the level a bit with the wheel off to push the pistons out a bit closer to the rotor face. Slip the wheel on and then you should be set, provided that was the problem.

  8. #8
    the wrench
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    oh i just remembered something

    just open the bled screw enough to getthe fluid flowing. if the bleed screw if backed out too far(1/4 turn will make a difference) then it will let air back in through the threads. especially when bleeding from the bottom up bernulies(sp) principal will actually cause air to be sucked in.
    do it, do it DO IT!!
    DOOOO IIIIIT!!

  9. #9
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    Quote Originally Posted by mtbgrasshopper
    I'm wondering how much of a distance the pads are from the rotor face.
    I would try pumping the level a bit with the wheel off to push the pistons out a bit closer to the rotor face. Slip the wheel on and then you should be set, provided that was the problem.
    They more or less sit on the rotor, after bleeding with pistons extended (some old pads in to stop them over extending) pushing them fully home and pumping up the lever. They don't retract much at all. Gonna try bleeding once more before some new seals and pistons to see if the retraction issues settle down...

  10. #10
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    Quote Originally Posted by Ridethebike
    Sounds like you have you have the basics covered. Always push the fluid up using a syringe(60cc) Some tips that help me. Is the caliper bleed/hose in a vertical position, air can be trapped in the caliper. Also make sure the bleeder on the master is at the highest point.like 45 degree angle. Then stick that plastic nipple from the Hayes kit in the master with a hose in a small bottle of brake fluid and pump the lever, as you pump the lever air bubbles will go back an forth and finally into the bottle Hope this helps.
    -Ride
    Thanks. Do you push the pistons back and use old pads/spacer to stop them coming out when working the lever?

  11. #11
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    Quote Originally Posted by garboui
    oh i just remembered something

    just open the bled screw enough to getthe fluid flowing. if the bleed screw if backed out too far(1/4 turn will make a difference) then it will let air back in through the threads. especially when bleeding from the bottom up bernulies(sp) principal will actually cause air to be sucked in.
    Good thought. I've had one very leaky screw on another bike that needed thread tape to seal it...

  12. #12
    FredoShizzle
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    There is a small spot in my Hayes XC calipers that can trap air. It's tiny and next to one of the screws that hold the two halves together. I can't find a decent photo to post, so in my best words... on the brake mounted to the fork, look for the bolts that hold the caliper together (as opposed to the bolts that hold the caliper to the fork adapter). Towards the front of the bike, in forward of the upper bolt, just above the S (for HayeS) is the pocket where air gets trapped.
    You really need to turn the caliper around and tap it to force bubbles out of that crevice.
    I bleed the lines, close the system, turn the bike upside down and tap the caliper as I rotate the bike back upright. Bleed again and I'll bet you have some bubbles.

  13. #13
    shut up and pedal
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    Quote Originally Posted by Haggis
    Thanks. Do you push the pistons back and use old pads/spacer to stop them coming out when working the lever?
    Pistons fully compressed and brake pads removed. New or old don't chance contaminating w/brake fluid along with the rotor/wheelset removed. Working the lever with the bleed screw open and connected to the syringe will not push out the pistons only the trapped air.

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