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Juicy 3 rotor 'TING!' noise

mr mangosmr mangos Posts: 174
edited October 2007 in MTB workshop & tech
Evening all,

I've got juicy threes with 185mm rotor on the front. The back has a 160mm and is fine. Problem is even though the brakes are aligned i.e. the front spins silently when lifted off the ground, I'm getting this annoying 'ting' noise when riding. Seemed to be worse round corners and over bumps so I checked it out. It's the same sound my rotor makes if I gently tap it. It also happens if I give the front tyre a bump sideways. The front QR is nice and tight. There is an even gap on both sides of the rotor when I check the caliper.

So I think it might be to do with flex in the fork or wheel. Fork is a Suntour XCM, wheels are Alex PC19 on no-name hubs.

It's not really affecting performance I don't think, but could flex be causing it? Would a better fork or wheel stop it?

Cheers for any input.


  • nicklousenicklouse Posts: 50,675 Lives Here
    fork flex or hub bearings need adjusting or replacing.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • mr mangosmr mangos Posts: 174
    Might just be the cheapie fork then. Forgot to mention there is no lateral play in the hub.
  • It could be your brake pad spring is not quite tensioned enough and allowing your pads to vibrate against your disc - Me and a mate of mine get this on our stumpy's which both have Shimano disc setup's - it may be worth a look.
  • Neily03Neily03 Posts: 295
    I get this sometimes on the rear with my Juicy 7s...
  • mr mangosmr mangos Posts: 174
    The plot thickens here! I've just spent 30 mins or so having another look at the brakes. It turns out what is actually happening is the concave/convex shims on the calipers are hitting the 'arms' on the rotor. If I use the avid method of caliper alignment the shims hit the rotor. I aligned them manually and the problem is solved, for now.

    Is it feasible to get disc mounts faced to give me a bit more clearance? We're talking less then 1mm though.
  • jaysonjayson Posts: 4,606
    Sometimes disc brakes do rub a little, its just one of those things im afraid. My front brake rubs occasionally just through the flexing of my forks, theres really not an awful lot u can do about it.
  • habitrailhabitrail Posts: 109
    you can face disc mounts, ya local bike shop should be able to do this. It sounds to me like you are just suffering the normal thing of rotor flex etc.. all disc brakes do this, esp when cornering. Just make sure ya rotor is in the middle of the caliper and ya should be fine.
  • mr mangosmr mangos Posts: 174
    Yeah I know what you guys are saying but it's not caliper rubbing. It's basically part of the mounting hardware hitting the inner part of the rotor, not the braking surface.

    Anyway, I put a 0.5mm shim between the dropout and the hub. This has moved the rotor away from the mount slightly and seems to have fixed it.

    Still confused as to how the problem developed. I've been running the brakes for months with no problem till now.
  • nicklousenicklouse Posts: 50,675 Lives Here
    your bearings will have bedded in now allowing things to sit differently.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Mine used to do this, and sometimes does when i realign my calipers (im using avid bb5 brakes though). Realigning fixes it.
  • ProwlusProwlus Posts: 539
    This is a very common problem with the avid range . Both my juicy 3 and 7 make this warbling noise if i'm going slow
  • Paul ShPaul Sh Posts: 607
    If you have quick release wheels having them done up to tight also causes it.
  • mr mangosmr mangos Posts: 174
    I thought that but the front QR starts to tighten when the lever's in line with the skewer. Didn't want them any looser than that. I'll stick with the shim for now but might look into facing if it crops up again.
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