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Brake HELP!!!!

Discussion in 'Technical and Troubleshooting Torque' started by removed-6, Aug 25, 2007.

  1. Track day looming and an unforseen problem has arisen.

    Took the bike around the block to make sure everything works OK, first 3 corner fine. Last corner, front brakes stay on, lever rock hard. OK so I get a spanner and release the bleeder nipple on the brake lever and brakes release OK. So I drain brake fluid, as this was one thing I was yet to do anyway, fill up the reservoir with nice new fluid and commence bleeding.
    Now, lever is feather light and does not seem to be pumping any fluid down to the calipers. So I can't bleed the brakes as there is NO pressure. Pulled the master cylinder apart and all semms OK, lines are all OK, caliper pistons are moving in and out.
    However, when I push the pistons back, instead of pushing fluid back up to the reservoir, they only push against the other caliper, and none to the reservoir?
    I don't know what is wrong or if I am doing something wrong?

    Any suggestion people of great knowledge?

  2. put it all back together.
    fill up the reservouir.
    open the bleed valve
    sqeeze leaver till bored or until u start seeing fluid come out.
    wait a while
    If u dont get any action its ok
    close bleed valve

    Repeat this
    -sqeeze the lever
    -grab a 10mm spanner or what ever size your bleed valve is.
    -while the lever is still sqeezed open and close the bleed valve quickly
    -it should ejeculate
    -release the lever
    repeat about 10 times or until bored/100% satisfied
    then do the same to the brakes
  3. I got a radial master cylinder on my bike, has a bleed nipple.
    I personally like to:
    Connect everything,
    Top up fluid,
    Pump the leaver a few time,
    Get a syringe connect it to the tube connected to the bleed nipple. Suck the fluid through while pumping. Use the nipple on the MC, then the further away caliper, the the closer one.
    Once pressure is there. Then just the usually.
  4. Z bike, I can't do what you say, there is NO pressure, that's the problem.

    Natta, I tried to suck the fluid through with a syringe and all it does is suck air from around the thread of the open nipple.
  5. how long are you spending squeezing the lever? it took me about 40 mins of squeezing to get pressure after i put in braided lines.
    brake bleed kits cost about 40 bucks from repco.

  6. theres alway presure
    go back and try again
  7. NO there's not always pressure!

    I found the problem in two parts.

    First, the new bleeder nipple Peter Stevens sold me was the wrong one and was sucking air, therefor, no pressure.

    Replaced and commenced bleeding, got a spongey lever at best, went for another ride, same thing happened, front brakes locked on after a few braking attempts. So, knowing that the pressure and the brakes were released when I opened the bleeder on the master cylinder, I proceded to dismantle my road bike and replaced the master cylinder with the one from it.

    Ta da!! All fixed, almost instant lever, normal bleed and all is good. :grin:

    So now I will have to get a new master cylinder next week to make my bikes all right again, and while I'm at it I will call TW Performance and get some braided lines. :wink:

    PI here I come.
  8. I'm getting an impression about you mate and it's not shiny and bright.

    Triway, great work, hope you enjoy the track day mate!
  9. Sounds like the releif port in the original master cyl is blocked? It is a tiny hole drilled in the bottom of the reservoir, usually about 10mm or so towards the brake line end of reservoir.
    It's purpose is to let line pressure off when the lever is released, and it can also cause issues with bleeding, as once you have air in the system, the releif valve will not allow it out, and then you have no incompressible fluid to pump.
    A very fine wire usually cleans it out on the bike.

    Regards, Andrew.
  10. Hey thanks Andrew, I will check that out first. Hopefully save myself a coupla hundred bucks.
  11. If you have the master cyl off the bike, may as well put a kit through it, and also you can clean it properly with a good soaking in alcohol then!
    For a track bike, it would be well worth it.

    Regards, Andrew.
  12. :LOL:

    OT, but not always. Even if everything is good, some bikes master cylinders are too small compared to the caliper pistons. The pistons just rock back and forth on the seals.

    So some bikes you need to wedge something under one set of pads to get the other to seat, then pull the wedges and pump some more.
  13. :LOL: :LOL: :LOL:
    ah huh huh...
  14. well glad u got it sorted.
    For 90% of people that give up too early.
    my advice would have been good.
  15. Am I wrong to think that draining the system annd re-filling it is not the preferred procedure? Better to flush out the old fluid with new, and keep air out as much as possible?
  16. It's the way I do it, otherwise there's always a bit of air somewhere you can quite get too.
  17. But then you also mix old fluid and new, as well as that I was changing the dot rating so didn't want to mix them either. If you bleed properly there should never be any residual air in the system.