Hydraulic Brake Disc Noise

navrig2
navrig2 Posts: 1,851
edited March 2014 in MTB workshop & tech
I've got a problem with my wife's Whyte Caledonian hybrid's brakes which I am struggling to solve. I cannot always replicate the noise when I try the bike but it always appears at some point during her rides. Initially I put it down to tyre noise but eventually I managed to make it happen but I am not sure how. The brakes are Tektro HDC-330.

There is an intermittent noise which seems to come from the rear brakes. This afternoon I did the following:

I ran the bike in the work stand whilst changing up and down the gears, operating the brakes - the brakes were silent.
I checked the wheel is seated properly in the drops.
I centered the calipers by releasing the fixing bolts pulling the brake lever and retightening.

I then had my wife test it. Initially it was silent and then, she says, when she built up speed it started.

I then pumped the brake lever and had tried it myself and again silent UNTIL I pulled the rear brake lever and it started. It's not a friction noise more like something drawing air or expelling fluid - there is a definate "wet" element to the noise. There is no sign of any brake fluid leak and whilst the brake lever pulls half way before it bites the brakes bite well and there is no fade. The lever never gets as far back as the grips.

She did the same thing - pumped the lever and then cycled, again it started when she used the brake.

Has anyone got any ideas?

Comments

  • The Rookie
    The Rookie Posts: 27,812
    What does the noise actually sound like? Brakes do make noise, if it's not a lot, you accept it and get on with cycling!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • navrig2
    navrig2 Posts: 1,851
    It's not a friction noise more like something drawing air or expelling fluid - there is a definate "wet" element to the noise.

    It's loud enough for her cycling friends to describe it as annoying.

    It is not just usual brake noise.
  • cooldad
    cooldad Posts: 32,599
    If it was doing either of those things, and loud enough to hear, you'd have no brakes in about two seconds.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • navrig2
    navrig2 Posts: 1,851
    cooldad wrote:
    If it was doing either of those things, and loud enough to hear, you'd have no brakes in about two seconds.

    I know that but still can't work out what the noise is.
  • The Rookie
    The Rookie Posts: 27,812
    Does it only happen at speed? Maybe the disc shape is drawing air into the gap and then it coming out, try a test by removing the brake calliper and see if it really is the brakes!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • navrig2
    navrig2 Posts: 1,851
    The Rookie wrote:
    Does it only happen at speed? Maybe the disc shape is drawing air into the gap and then it coming out, try a test by removing the brake calliper and see if it really is the brakes!

    I am reasonably confident that it is linked to the brakes because after pumping the lever a few times the noise is then instigated by pulling on the lever whilst moving.

    There is no degradation in performance of the bike - brakes work well, no apparent (frictional) drag, no sign of friction rub on the rotors - just this very annoying noise.

    Initially I just assumed it was tyre/road noise but after being able to initiate it myself I know it is not.

    That said I will take off the caliper, tie it up and try the bike.
  • Terrytibbs
    Terrytibbs Posts: 76
    Depends just how loud it is/ But does it sound like it's coming from the caliper/pads/rotor or from the lever? If it's not too loud, your diaphragm on your lever may need replacing. If it's damaged it may be sucking in air then expelling it. But sounds like it could be a tough one to diagnose without hearing it.

    Also check the hose for any tiny little kinks, nips or holes. Your brake can still operate normally for a while even with a leak in the hose.
  • navrig2
    navrig2 Posts: 1,851
    Terrytibbs wrote:
    Depends just how loud it is/ But does it sound like it's coming from the caliper/pads/rotor or from the lever? If it's not too loud, your diaphragm on your lever may need replacing. If it's damaged it may be sucking in air then expelling it. But sounds like it could be a tough one to diagnose without hearing it.

    Also check the hose for any tiny little kinks, nips or holes. Your brake can still operate normally for a while even with a leak in the hose.

    Pretty certain it is the hub but will check. The bike was brand new in the autumn so if a faulty lever it will be a warranty claim.

    I'll check over as you suggest. Ta.
  • Terrytibbs
    Terrytibbs Posts: 76
    If it's definitely down by the hub then it may just be normal brake noise. Some brakes/rotors can make a strange noise when moving and pulled and when heated up a little. It can sometimes sound like a whaling noise and it is a really odd sound and the brake still works well.

    As long as it's not a squealing noise because you may have a burnt out rotor or contaminated pads, but it sounds like you'd know if it was a noise from a lack of grip between the pads or rotor. The brake will still work well if it makes a whaling noise. Suppose sometimes this noise can sound a bit like a Turkey :roll: I'm actually being serious believe it or not haha.

    Sorry, it's hard to explain, but may just be that.
  • kajjal
    kajjal Posts: 3,380
    Terrytibbs wrote:
    If it's definitely down by the hub then it may just be normal brake noise. Some brakes/rotors can make a strange noise when moving and pulled and when heated up a little. It can sometimes sound like a whaling noise and it is a really odd sound and the brake still works well.

    As long as it's not a squealing noise because you may have a burnt out rotor or contaminated pads, but it sounds like you'd know if it was a noise from a lack of grip between the pads or rotor. The brake will still work well if it makes a whaling noise. Suppose sometimes this noise can sound a bit like a Turkey :roll: I'm actually being serious believe it or not haha.

    Sorry, it's hard to explain, but may just be that.

    My front brake did the turkey noise until I tightened the QR, loosened off the hub as it was too tight and went fast down a long steep hill dragging the brakes. After that silence ;)
  • navrig2
    navrig2 Posts: 1,851
    Kajjal wrote:
    Terrytibbs wrote:
    If it's definitely down by the hub then it may just be normal brake noise. Some brakes/rotors can make a strange noise when moving and pulled and when heated up a little. It can sometimes sound like a whaling noise and it is a really odd sound and the brake still works well.

    As long as it's not a squealing noise because you may have a burnt out rotor or contaminated pads, but it sounds like you'd know if it was a noise from a lack of grip between the pads or rotor. The brake will still work well if it makes a whaling noise. Suppose sometimes this noise can sound a bit like a Turkey :roll: I'm actually being serious believe it or not haha.

    Sorry, it's hard to explain, but may just be that.

    My front brake did the turkey noise until I tightened the QR, loosened off the hub as it was too tight and went fast down a long steep hill dragging the brakes. After that silence ;)

    Interesting. When the bike is on the workstand the front wheel wont spin for very long. Perhaps the hub is too tight!

Categories