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Brake Bleeding Help !

Discussion in 'Technical and Troubleshooting Torque' started by Donshe, May 15, 2010.

  1. Sorry for the new thred but this is a more specific question.

    Set about bleeding my front brakes today, did one whole cycle of master, right and left.

    And then I think I let my master drop too low.

    As a result of this or whatever it is Ive done, the brake lever no longer has ANY braking. I believe Ive got a lot of air in there :/

    Im looking at doing a reverse bleed tomorrow morning when I can get my hands on a syringe. Just wanted to ask if this was the right course of action.

    Do up all bleeders except the caliper Im pumping in from, pump in and remove fluid from resevoir as it comes up


    PS. Also, should engine oil level be checked when the bike is warm or cold.
  2. You will have to pump the brake lever a bit after bleeding the brake, try squeezing the lever several times to push the fluid back into the pistons.

    Check the oil when the bike is warm.
  3. Sorry mate, I should clarify. I never finished bleeding

    Resevoir is currently full. Brake lever has no pressure at all, can't seem to get any fluid out form nipples to get it flowing again.
  4. Sounds like you didn't fill the master cylinder up soon enough when bleeding the brakes, so therefore you have drawn air into the system.

    I would start bleeding them again, making sure you don't let the master cylinder level drop too low. You will have to do both calipers again. It might take a little while, but at least they will have nice new fluid running in the system.

    I am not sure of the reverse bleeding you spoke about, but it sounds like it would be easy to make a mess with lots of fluid. Make sure that you don't get any of the brke fluid on the painted surfaces, etc.
  5. Do a reverse bleed, Supercheap have an oil injection syringe that should do the job for about $7.

    Good luck!
  6. This is much easier with 2 people.
    1. Crack bleed nipple/s
    2. Squeeze brake leaver
    3. Close bleed Nipple
    4. Release leaver
    5. Repeat until only fluid is coming out

    Oil levels can be checked cold. Its more accurate than waiting for the hot oil to be collected in the sump again (wet sump) and potentially over filling thinking the level is down.
  7. Yep got myself a syringe, going to reverse bleed.

    Just crack a caliper nipple open and feed it in right, no need to depress the front lever?

    Also wit hthe oil, Im hearing conflicting arguements, at the moment, the oil level is PERFECT when cold, but if I start the bike up, obviously oil is in the motor even if its turned down and the viewing glass is empty.

  8. Donshe, when you bled the brakes did you have one or both nipples open? I'm guessing that as you released the brake lever one of them might've been cracked open and air got sucked in.

    You need to do one side at a time.

    If this reverse bleeding doesn't work, or if anyone reading this wants to bleed the brakes and hasn't done it before, try doing it this way:

    1. Ensure that the master cylinder is full. Connect a clear plastic hose to the nipple and discharging into a container.
    2. Pump up brake.
    3. Hold lever in. Open one bleed nipple slowly. Let lever go to handlebars.
    4. While holding lever in, close nipple.
    5. Release lever slowly. Watch the level drop in master cylinder as fluid gets sucked into the line.
    6. Pump brake up again. Repeat Step 3-5.

    Do this until clear fluid comes out of the nipple.

    Repeat for the other side.

    The best way to bleed brakes is via a pressure method. This involves placing a fitting over the master cylinder, and pumping it up with fluid via a hand pump connected to a bottle of fluid.

    You don't need to pump the lever or pedal. You pressurise the system, then open the bleed valves (nipples) until all air and clean fluid comes out.

    When the brake lever/pedal is up the valve from the cyl. to the line is open. Pressing the brake lever in closes that valve and forces fluid onto the brakes. Releasing it releases the pressure and if it's needed, sucks more fluid in from the reservoir.

    I haven't done this reverse bleed thing before. Let us know how it goes. Presumably you need to do something about fluid squirting back into the reservoir and up and out of it. Last thing you want to do is to have it squirt over the paintwork to ruin it.
  9. If you just sucked a bit in at the master cylinder try this:

    Pump the lever a few times in quick succession. You should then get a bit of lever feel. Then crack the banjo a the master cylinder.

    Air tends to accumulate at that location on bikes.

    Failing that, check to see if the pads are seated on the disc. From a volume perspective motorcycle master cylinders are not big enough. With a bit of wear and tear they won't pump 8 pistons back down onto the disc. The pistons just tend to rock on the seals.

    To get lever pressure if this is happening you need to "jam? something under 3 of the pads. Obviously be careful what you use and be careful not to warp the disc.

    Once one pad is sitting on the disc you can remove the packing from another pad and repeat.
  10. Good work. That should fix the problem, but there's plenty of other good advice in this thread if not. Make sure you have a good seal between the syringe & the nipple so you don't get any air in. Bunnings sell a suitable tubing that will do the job.

    With the oil, I would suggest you consult your manual. Some bikes need to be checked cold, some hot.
  11. How long are you waiting after running the engine before checking the oil again?