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The kitchen sink approach to brake issues

Discussion in 'Technical and Troubleshooting Torque' started by Loz, Oct 5, 2009.

  1. As y'all know, I ride an old shitheap of a Kwaka, and I tend to give it a bit of welly too, so maintenance is a constant battle against various bits that deteriorate as fast as I can fix 'em.

    Recently I've had to stop coming out on twisties rides, partially because I'm as busy as a one-armed man in a wanking contest right now, but mainly because my front brake lever has been coming right in to the bar before it starts doing much. Holster discovered this after we very narrowly avoided a 4WD that meandered out in front of us 2-up on the Gembrook road. Not much fun. And disappointing, since this used to be a 2-finger stoppie bike.

    Here's the steps I've taken to try to sort it out, and whether they made any difference in this case:

    1) Bleed the bollocking things - fail
    2) Bleed them again - fail
    3) Replace pretty sorry-looking rubber lines with steel braided lines - fail (!)
    4) Bleed again - fail
    5) Disassemble master cylinder, replace piston and seals (thanks Kenny!) - fail
    6) Crack the shits
    7) Deep breath
    8) In my most recent attempt, I've stripped and cleaned both 6-pot calipers (thanks Pete the Pom and Roarin for advice and f*ckup-fixing), used a dremel with a wire wheel to gently remove all the built-up scum behind the seals, cleaned the caliper halves until I'd be happy to eat my dinner off them, replaced the seals, dust seals and o-rings with freshies (thanks to Troy @ Race Rep - he's the man for Kwaka parts) and reassembled. I've also put on a set of brand spanking new Metal Gear discs and pads, because the old discs were getting a bit thin (thanks to anonymous buddy).

    So I've pretty much cleaned, rebuilt or replaced every f*cking compnent in the braking system, and spent buttloads of money and time in the process. This is the kitchen sink approach to brake maintenance.

    I'll be putting the thing back together tomorrow, assuming I can get Cheng to help me with an unrelated fork job sometime tonight, and then I'll know if the situation's any better.

    If it's not, there'll be a bonfire at my house tomorrow with a Kawasaki in the middle of it. Bring marshmallows and other Kawasakis if you've got 'em.
  2. Hmmm, try the lever on the right hand side maybe?:butt:
  3. Bend the lever away from the bar ?

  4. Old trick for brakes that refuse to bleed is to go through the usual procedure and then strap the lever to the bars with a big rubber band and leave it overnight.

    Another thing worth trying is to take the caliper you're bleeding off and elevate/orientate it so that the bleed nipple is the highest point in the system.

    I've also seen old tyre valves grafted into spare master cylinder lids to provide a bit of pressure, and fluid injected into the system through the bleed nipple with a big syringe to bleed it from the bottom, although I've never tried either myself.

    Generally I find that brakes fall into two categories. Those that almost bleed themselves and those that take a solid week of stuffing around.

    Good luck.
  5. You may find that this does the trick. The old Suzuki used to come to the bar if the pads were worn and the disc was a bit thin.

    I think the pistons used to get knocked back during riding and then the volume of the master cylinder wasn't enough to push the pistons all the way back.

    I eventually ended up going to a larger master cylinder. This gave me the volume to push the pistons home all the time, but I lost some power as a result.

    Also, have you tried cracking the banjo bolt at the master cylinder to bleed them?
  6. So what time??? We have a packet left over from saturday night(y)
  7. Time for a new bike.
  8. um, why is one of the tags on this thread 'penis' ?!
  9. Try ditching the "ewe bewdy let's go racin soopa doopa" pads for a more generic style. Common failure of top-notch pads in a not-so top-notch environment is they don't get enough latent heat to their material base and can be literally gliding on the disc before friction coefficients get to the sweet spot. The top-end pads are designed purely around top end conditions, and usually in conjunction with appropriate rotors and calipers etc etc.
  10. Nah, these brakes are really bad. At a standstill, with moderate pressure you can bring the lever back to the bar. Frightening.
  11. See that sounds more like an issue with the master or slave cylinder seals (assuming lines have already been replaced), has nothing to do with pads or rotors, even thin rotors and pads shouldn't let you pull the lever back to the bar if the hydraulics are ok (seals, lines, fresh fluid etc)
  12. I'd already replaced the master cylinder seals and piston when Cejay had a grope of me levers.

    I replaced the discs and pads because they needed it, it was coincidental. The old pads were cheapie ones I was testing for Kenny - but the lever pressure issues started back when I was using my trusty ol' EBC HH pads. So I think we can rule pads out of the causes.

    I still haven't been able to reassemble the bike to see if the new caliper seals have worked or if I need Stewy to bring them marshmallows over. But I'll get there.
  13. Could you pump it up?, ie it pulled back the bar the first time but after a few more pulls, it held pressure away from the bar?

    (like you haven't already tried these things :) )
  14. After no luck on the GR one time - brakes behaving the same as Loz's (though because I'd changed lines and pads) - I tried this and what a difference! Immediately the problem was solved, and better than ever. Wouldn't bother doing it the other way now.
  15. A little bit.
  16. It would probably be more than "a little bit" if it were just hydraulic (seals/air/hose) issues.....

    Is it back together?, did you have any luck?
  17. Diagnostic info: does the lever feel 'spongy', or no resistance until it comes right back, or solid, but continues to 'sink' under pressure?

    'Nother (possibly silly) question; how's your wheel bearing?
  18. Not back together yet, I need to straighten something I've bent in one of me forks. Well, that is to say something I bent in BOTH me forks, but I've only fixed one, thanks to Roarin.

    Wayne, the lever had virtually no resistance until it came right back near the bar. I think the wheel bearings are OK, if it was a wheel wobble pushing the pads back and out then I reckon I'd have spotted it!
  19. Too much free play/slack in the system somewhere... The holes at the lever pivot point or caliper mounting points haven't elongated have they? I had that with the VFR once.
    I'd still go along with the PatB/MattyB bleeding system as an option.
  20. Did you bleed the air from the master cylinder before refitting it to the bike, i.e in a bench vice by pushing the piston with a screwdriver while lightly covering the outlet port on pushing in and closing the outlet tightly with your thumb when releasing.
    May be different for bikes with only one caliper to worry about but as a mechanic i have a hard time bleeding a system on a car if i dont first bleed the master cylinder when replacing it. Just a thought