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Front brake disc warped?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by theeICEMAN, May 26, 2011.

  1. So...I was told by a mechanic that my front brake disc is warped..

    I don't see anything wrong with, neither does another mechanic that I went to.

    So a couple of days ago I left my bike out (sheltered area) except for the front tire bit in the rain and wind.

    I came back to it 1 day later, my front brake disc has rust on it?
    I wiped the rust off, and went for a test run, still works fine, after applying the front brakes during my test run, I came back and it was all fine (looking normal as well)

    oh and when I put the bike to N and let it roll, I can hear little noises like screeches, sounds like the front brake pads are rubbing against the disc, however the front brakes werent applied

    So what do you guys think?
    And also to install/replace the front brake disc is it as easy as taking the front tire off and then unscrewing the allen keys off the front brake disc from the rim?
  2. Sounds fairly normal to me. A warped disc will generally try to rattle your teeth out under braking. If there's no vibration it's fine.

    Pretty much.
  3. As per PatB, does the bike vibrate/shudder when braking? Or do you feel a pulse through the lever?

    Either of those may suggest a warped rotor
    or maybe not
    The Warped Rotor Myth

    A faint grinding noise from pad-rotor contact when pushing the bike around is normal
  4. If your gunna pull the disc off, use a little loktite 243 on the studs when you put them back in
  5. Get the bike just rolling and gently apply the brakes until they are just touching. If a disk is warped you will be applying greater pressure to the high spot than to the low spot. As the disk rotates you will feel this as puling back through the brake lever. If you squeeze tightly you may or may not feel this depending on how badly warpage is.

    You can also test it with a specially designed instrument with a name which eludes me after several glasses of white. Runoutmeterometer???

    Grinding is more likely to be associated with either the rust on the disk or pad not entirely free from the disk. The latter may be but is not necessarily due to warpage.
  6. My VTR250 does that, but only during very low speed manoeuvring. I thought it was the disc too but the brake lever doesn't pulse.
  7. That would be a Dial Indicator :wink:

    As the others have said, the easiest test will be feel through the lever. If it pulses, you have a problem.