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Squealing brakes of death

Steve_b77Steve_b77 Posts: 1,680
edited February 2011 in MTB workshop & tech
On my Cove Handjob I've got a set of bogo Deore hyrdaulics, last time I rode the bike (3 weeks ago) the brakes were fine, yesterday out in Delamere, first proepr braking moment they squealed like a stuck pig and completley lacked power.

They continued to squeal and be lacking in power for the next 2.5hours, an attempeted trail side fix of sanding the rotors and pads did very little to improve things.

The lever feel isn't any different to before, they just don't stop - nearly hit a tree at one point.

The rear one got slightly better but the front is bloody awful.

Pads are in good nice, rotors are still true.

Bike hasn't been washed in weeks and stored in my bike room so nothign has gotten onto the discs, any ideas?

Posts

  • nicklousenicklouse Posts: 81,520 Lives Here
    to squeal and be lacking

    contaminated.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Steve_b77Steve_b77 Posts: 1,680
    Just wondering how they got contaminated as they were fine at the end of the end of the last ride - I then rode home and put the bike away.

    Took bike out of shed, rode to forest and nearly died on first descent.

    How would they get contaminated in the between sat in my bike room? Not ridden on the road between rides and not even cleaned the bike.
  • .blitz.blitz Posts: 6,588
    Brakes do funny things even when parked.

    I have Deore brakes on my Chucker and they make about as much noise as a desk fan. I've cleaned the rotors with wire wool and warm water (both sides) and then give them a squirt of brake cleaner. The calipers seem to need fairly careful alignment but nothing out of the ordinary.

    I would clean them up and go through the bedding-in procedure. Some hard stops and a bit of heat often works wonders.
  • Steve_b77Steve_b77 Posts: 1,680
    Think I'll get to it at the weekend, bit of a strange occurance as it's the first time I've ever had it happen :?
  • Try this

    Ride holding the offending brake on. Do until the rotor is too hot to touch.

    If not contaminated with oil they will now be fine

    Or take it to your LBS who will charge you £25.00 and do exactly the above
    Racing is life - everything else is just waiting
  • cavegiantcavegiant Posts: 1,546
    If the pads are sintered a gentle bake at gas mark 3 (not four, seriously not 4) for a while is a good way of relifing the pads.

    Never tried this with resin,
    Anyone baked resin pads who could advise?
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?
  • cavegiantcavegiant Posts: 1,546
    forgot to add you can do this too the rotors too, make sure they are full steel, not steel/alumium.
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?
  • bluechair84bluechair84 Posts: 4,352
    cavegiant wrote:
    gas mark 3

    WTF iz diz? Spek MO man!!
    :wink: Seriously, I might try this on a set of pads I have squealing at the mo. Will use google to translate it to the C21 :lol:





    Not that it matters... I just remembered my oven doesn't have any temps written on it... Cooking is completely guess work.
  • Won't help the poor power, but a little smear of copper grease on the metal back of the pads can help them stop squeeling like a stuck pig.
  • cavegiantcavegiant Posts: 1,546
    cavegiant wrote:
    gas mark 3

    WTF iz diz? Spek MO man!!
    :wink: Seriously, I might try this on a set of pads I have squealing at the mo. Will use google to translate it to the C21 :lol:





    Not that it matters... I just remembered my oven doesn't have any temps written on it... Cooking is completely guess work.

    Gas mark 3 is below half on my oven, so go a quarter through to be safe. You want it hot enough that the pads smoke but not enough that the backing plate bends. The backing plate will lose it's paint, do not worry about that.
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?
  • FenredFenred Posts: 428
    Muc-off disc brake cleaner, spray the whole rotor and pads, leave to dry, go outside, find a hill, ride down it pullling several hard stops, should be quite as a mouse...Good luck!
  • Won't help the poor power, but a little smear of copper grease on the metal back of the pads can help them stop squeeling like a stuck pig.

    yup thats wjat we do to squeeling brakes on cars, no reason why this couldnt help with bikes too
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