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Spongey brakes?

Discussion in 'Technical and Troubleshooting Torque' started by ~DadAgain~, Aug 2, 2010.

  1. My '05 ZX636R recently had its first major service under my ownership. For reasons of warranty and my own mechanical ineptitude the service was performed by the dealership where the bike was purchased.

    ....On taking the bike out from the dealership I was at first of course releived to get back on the bike (and off the crappy 250 they gave me as a courtessy bike) - and also releived that there were no nasty expensive things that came up in the service - all good.

    The brake (front) felt a little softer than before - but was still perfectly fine. Perhaps just me re-adjusting to a newly refreshed bike?...

    Now three weeks later, I'm sure the brake has got softer again. This morning I'm convinced I was able to pull the brake hard enough to touch the lever to the throttle - definately not a good thing... Wheres the room for an extra hard squeeze if I need to stop in a hurry?...

    So I've taken a look at the service manual to see if theres any clues - the 'adjustment wheel' is set to '1' (maximum distance between grip and lever).

    Is there a simple way I can fix this - or do I need to face up to the dealership again and try and get them to rectify it before I die horribly in 'not-stopping-in-time' kind of way?
  2. you may have air in the lines try bleeding your brakes
  3. Your brakes should be, if anything, firmer after a service, rather that as you describe them now. I would definitely be pursuing this, but you face the age-old dilemma of taking it back to to a place that didn't get it right the first time (whatever it was they did). I suggest you get another mechanic who you trust to check out the situation, and then go back to the dealer in question with his report......
  4. I just phoned the mechanic and he's agreed to do a quick check and bleed of the brakes this afternoon if I swing by. \\:D/

    He did mention that 05/06 ZX6s have some unusual master cylinder which frequently has seals that 'seep' a little and let in air when they get older and and talked about softening up the seal by parkng the bike with brake lever zip-tied closed over night for a couple of nights - and suggested that ultimately the master cylinder will need a replacement ($140? apparently). :?

    Whether all that is just standard mechanic BS I dunno - but I guess if he can fix the immediate problem while-I-wait this afternoon I'll live with it.
  5. $140 for a master cylinder? **** off! He will charge an hour on top to install it.

    The zip tie trick shouldn't work unless the seal was never fitted correctly or the parts the seal fits around were not manufactured correctly to accomodate the seal and it does indeed require time to be force in or change shape. But that is not in the design of a seal, it shouldn't change shape...and will work to come back to normal.

    Is there a tension adjuster on the brake cable?
  6. Fixed.
  7. Cable??

    If they changed the brake fluid at the service, and you lever is getting progressivley worse, I would suspect a leaking bleed nipple. Probably the one on the master cylinder but it could be on a caliper too. Have a look around for any brake fluid leaking at those points.

    Correct me if I'm wrong but I think it's a Niisin Radial M/C. Gixxers use a similar one and bleed nipples are known to have to be replaced sometimes.
  8. I'd be looking for fluid leaking from either the master cylinder or the bleed nipple on the caliper. It may be as simple as the gasket under the master cylinder cap is shot and is sucking air. Bleeding ht lines will sort out the sponginess...but unless the system is airtight it will come back.
  9. I took the bike to them yesterday evening and they bled the brakes - its much better now - but I'll be keeping a close eye on it.

    They did also give me a couple of zip ties! (generous eh?).

    I guess I'll check for any seeping brake fluid over coming weeks and perhaps I'd better learn how to bleed them myself (it didnt seem to take them very long - so surely its doable? even by an mechanical incompetant like me)
  10. Bleeding is not a difficult task, although it can be a pain in the rear if you have (as you do) two bleed valves. I imagine it would be the same process just messing with the extra nipple though. anyone able to confirm/deny/enlighten?
  11. When I replaced the brake fluid and hoses on my 05 636, I just bled it sequentially - top nipple then right then left. No special procedures.
  12. Remember with brakes your life is on the line. If you are in any doubt get a trusted professional to do it for you, or at least check your results when you are done. As Nikuya says, it's not difficult, but it must be done properly.

    Bleed one section at a time, be patient, and get a friend, wife, boyfriend or significant other to pump the lever for you, it makes life a lot easier. Bleed the M/C first (if it has a bleed nipple, some don't), then one caliper, then the other. Check the lever for pressure/sponginess, sometimes re-bleeding the first caliper will remove more air, I think it has to do with the configuration of the lines.

    A lot of mechanics use a vacuum bleeder to suck the new fluid through, it's very quick but not always perfect (perhaps it's operator error). I've seen many bikes done this way that still have air in the system (five bucks says this is what happened to the OP's bike). For my money a manual bleed is the only way to be sure all the air is gone.

    As an aside, filling an empty brake system with fluid is a bastid of a job if you don't have a vacuum bleeder..... I use the following method because I'm too tight to buy one.

    When starting with empty lines I use a dirty great big syringe to suck the fluid through the system (medical centres and fibreglass suppliers have them). Connect it to a rubber hose and connect the other end of the hose to the relevant bleed nipple, crack the nipple then pull the fliud through with the syringe, lock the nipple off when suction is over, and repeat. When you are not seeing any air sucked out of the system then bleed the lines manualy.
  13. Damn - back on this morning for a rider to work and I've deinately gt some more air in the line again.... brakes are soft and lever nearly gets back to throttle grip and pulled hard.

    Obviously this needs some kind of permanent fix!
  14. it must be leaking air somewhere, check the lines, seal on master cylinder, banjo fitting, bleed screws & thread, could be your seals in the caliper too
  15. Are you sure you dont have a warped disc? If the disc is warped as it passes through the caliper it pushes the brake pads apart hence when you go to use the brakes you have to move the pads back towards the disc again.

    Next time you roll up to the traffic lights brake gently and see if you can feel a pulsing through the brake lever. If it pulses there warped.
  16. Nope - definately isnt that.
  17. Take it back...

    I had spongey brakes on my 250 Ninja.

    Several people tried everything.
    Bled, re-bled, bled again. Syringed, vacuum pump, etc, etc.
    Changed brake lines, master cylinder, brake calipers, pads. Tied down the lever over night. Nothing worked.

    Took it in for it's regular service - didn't even mention the brakes.

    Came back perfect.

    I have no idea what they did.

    Not much help I'm afriad - except to maybe give you a bit of hope.
  18. Dadagain - where in brisbane are you?
    If you need help with bleeding I can lend a hand.
  19. I'm in The Gap - so kind of the wrong end of town for you. Thanks for the offer though!
  20. Seals worn at the master cylinder?