Viewing 14 posts - 1 through 14 (of 14 total)
  • frame resonance when scrubbing rear brake.
  • Premier Icon Wally
    Full Member

    Anybody found a solution?
    Tried new pads, rotor and realignment.

    My contact points find the vibrations really unnerving.

    Premier Icon Nobeerinthefridge
    Free Member

    Potentially a leaky caliper contaminating pads?.

    Premier Icon bri-72
    Full Member

    Rotor not centred on calliper?

    Mine sounds same. No rub and brake looks ok when spin wheel standing next to bike. But under braking the rotor (200 so more flex?) moves and contacts calliper body I think. Horrendous brake chatter and vibration and squeal.

    Premier Icon IvanMTB
    Free Member

    Not sure if I get you right, but I had terrible, howling resonance on my rear brake, on Ti HT if not pulling it down to the bars.

    Ended up taping very tightly, with electric tape, about inch long M8 bolt into brake side seatstay. From the top of the stay.

    Quiet and no resonance anymore. Friend of mine had the same on his FS bike. Same solution, same result.

    Cheers!
    I.

    Premier Icon Wally
    Full Member

    It is a Ti hardtail. Going to change all wheel bearings, freehub and install a spare XT rear brake complete unit with new pads and isopropyl alcohol the rotor. Will post up results. Taping on bolt will be last resort to alter resonant frequency.

    Exactly that, pulling to bars brake works perfectly. Scrub speed and it sets off the vibrations.

    Premier Icon matt_outandabout
    Full Member

    My old Sanderson did this when I first got it – I sanded down the thick pain and really cleaned up all the mounts and surfaces to bare metal on metal basically, solving the issue.

    Premier Icon Wally
    Full Member

    I had a Life and a Breathe, both silent and ran with lovely feel. Due to Ti, no paint to rub off.

    Premier Icon suburbanreuben
    Free Member

    Have you tried wrapping old inner tubes around various tubes? Find the singing pipe and look for a more elegant solution.

    Premier Icon Nobeerinthefridge
    Free Member

    Taping on bolt will be last resort to alter resonant frequency.

    Does it only do it at a certain speed? is it okay in the dry? It will be resonance if the frequency (rpm basically) is within 5%ish of the natural resonant frequency of the frame.

    If it only does it et, or does it across the speed range, it’s not resonance.

    Premier Icon Nobeerinthefridge
    Free Member

    *et meant to be wet, too late to edit!

    Premier Icon IvanMTB
    Free Member

    In my case it was just in certain speeds/conditions.
    Added bolt fixed problem.

    No other changes happened to that bike since, apart of new brake pads.

    Cheers!
    I.

    Premier Icon escrs
    Free Member

    You say you have realigned the caliper but can I ask how you realigned it?

    If you just loosened the caliper off, pulled the brake lever then retightened the caliper then that could be the issue

    If the pistons are not pushing out equally and squarely then this can cause the caliper to not be aligned properly when trying the above method and can cause uneven brake pad wear and give off resonance

    Best bet is to remove the caliper, then remove the pads, pump out the pistons a bit, give them a good clean with isopropyl alcohol, then push them squarely back in the bores (using a blunt plastic tool like a tyre lever as not to damage the pistons)

    Next refit the caliper (minus the pads) and centre it over the rotor by eye, tighten down making sure it doesn’t move, then refit the pads and pull the brake, the pistons should move out squarely and the pads should then evenly touch the rotor and not rub or cause any resonance

    Also worth checking your rotors are true and not contaminated

    Premier Icon bsims
    Free Member

    The only thing that cured this on my Trek was new rear brake under warranty. I have read people have glued some lead to the chain stay to alter its resonance; cant comment on that personally though. Could be the dreaded leaky calliper so start with that and dishwasher the rotors if you do to remove any deposits then replace the pads. I believe from experience that the fluid can seep into the pad and leach back out when heated so you can’t clean the them properly.

    Premier Icon Wally
    Full Member

    I really appreciate the advice and time people have spent. I will follow that escrs.

Viewing 14 posts - 1 through 14 (of 14 total)

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