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Permanently squealing RS785 disc brakes

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  • March 16, 2017 at 12:32 pm #26892
    stub

    I wonder if anyone has experienced this or something similar and can shed some light on this for me

    I’ve got a cyclo cross bike with the Shimano RS505 shifters and RS785 hydro calipers. When I first set them up, everything is fine. I go through phases of not using the bike a lot (tend to ride the road bike more often as I’m a fair weather cyclist), yet when I do, I find the brakes squeal terribly – almost like there is oil all over the rotors, front and back. Around christmas time I re-bled everything, and fitted new pads and rotors. I used the bike quite a bit then and everything was fine. The front brake has however got noticably soft (The pad is quite worn), yet I though it should self-adjust?

    I’ve just got the bike out after six weeks or so of non-use and gone to check it over – the brakes squeal with the tiniest pressure again. I can’t see any signs of leaks, there is no sign of oil anywhere, so I’m at a loss to explain it.

    Can anyone shed any light?

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  • November 8, 2017 at 3:49 pm #889037
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    stub

    I took to storing the bike

    I took to storing the bike horizontally rather than vertically. It made no difference. In the end I just decided to ride it.

    I’ve been ‘burning in’ the pads at some point on every ride. This is mainly on the front brake. It has made quite a difference. They do squeal a bit at the very extreme, but otherwise the braking is much better and pretty much squeal free. I believe the braking is not as good as a fresh pad and a fresh rotor however.

    I almost never use the rear brake at all (in general on any bike). I tried it on this bike the other day, and it had no stopping power whatsoever. No bite, no discernable decrease in speed at all.

    I will take both off and clean the rotors completely again and try new pads yet again, and see what happens.

    I have a feeling it is contamination on the rotors somehow? I don’t know though and I don’t know how to solve it if so…

    All I can say is I use the bike and it’s got better. Maybe something contaminated it originally and  is slowly wearing off, I’ve got no idea.

    I even bought a spare set of calipers in case they leaked but it’s been the same with both sets.

    November 5, 2017 at 11:00 pm #889035
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    Willeygoat

    Haven’t swapped calipers, as

    Haven’t swapped calipers, as they are new too.  In addition, when I put the new rotor and pads on, there was an immediate squeek, really no time for oil to hit the pads or rotor.

     

    November 5, 2017 at 8:14 pm #889033
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    beezus fufoon
    Willeygoat wrote:
    Any updates on your squeeky disc brake fixes?  I’m asking because I am at my wit’s end.  Have tried just about everything written, expressed or implied.  New rotor, new pads, however this only occures with a certain rear wheel. I can swap wheels and I don’t get the noise.

    I’m running 140 Ice Tech Shimano’s, so they are centerlok’s. 

     

    Haven’t tried the talcum powder yet, but I don’t see how that could be  a permanent fix.

    have you tried calipers?

    November 5, 2017 at 8:10 pm #889031
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    Willeygoat

    Any updates on your squeeky

    Any updates on your squeeky disc brake fixes?  I’m asking because I am at my wit’s end.  Have tried just about everything written, expressed or implied.  Cleaning, new rotor, new pads, cleaning again. However this only occures with a certain rear wheel. I can swap wheels and I don’t get the noise.

    I’m running 140 Ice Tech Shimano’s, so they are centerlok’s. 

     

    Haven’t tried the talcum powder yet, but I don’t see how that could be  a permanent fix.

    March 25, 2017 at 8:25 am #889029
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    Johnnyvee

    Sometimes this can be caused
    Sometimes this can be caused by the bolts or centrelock holding the disc in place being loose. A friend of mine went down all kinds if routes to stop squeals and it was the rotor fixing bolts.
    Just a thought and costs nothing to check.

    March 23, 2017 at 9:09 am #889027
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    IanEdward

    Well I had some partial

    Well I had some partial success today on a very wet cold commute.

    By pulling frequent, hard stops and attempting to drag the brakes as much as possible, they were slightly less screechy than usual, although I noticed an alarming and slightly obscene amount of vibration coming through the seatpost when using the back brake hard.

    Also all the additional braking gave me some valuable interval style training, although it made my commute about 10 minutes longer…

    Disc brakes, the wave of the future! smiley

     

    Joking aside, I’m going to the bike shop today, maybe see if they’ll consider new rotors and pads trade price at least. I notice Magura rotors (or a similar looking Spanish brand called ‘Galfer’) have loads of cut outs and edges and are designed to work far more quietly in the wet. I’d love to reduce the size of the rotors as well so they heat up more under braking, but I don’t think adaptors exist to reduce rotor sizes, only increase…

    March 20, 2017 at 10:17 pm #889025
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    matthewn5
    risoto wrote:
    Sorry, but that  is why I absolutely hate disc brakes. I got some mechanical Avid BB7 brakes, so no fluids, and they are ALWAYS noisy – from the very beginning I bought the bike. Everything has been cleaned and adjusted several times. Goes away for a few rides. Then squeling terribly again. This happens in the dry  and the wet. I keep my bike clean and still..I am conviced that  the slightest dirt on rotors provoke it. When I clean them with alcohol it goes away for a while=1-2 rides. You can’t even see that the rotors are ‘dirty’ enough to provoke anything. I have never had a problem with caliper brakes. In the future I will avoid disc brakes like the plague! Same thing happened with my first bike with hydrolic disc brakes. that was Shimano and just as noisy.

    I noticed this on the Dunwich Dynamo last year. Squealing brakes through quiet villages at night don’t make many friends.

    March 20, 2017 at 9:34 pm #889023
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    dantheman1979
    bauchlebastart wrote:
    Leaking piston seals?

    Happens often with Shimano hydro calipers.

    Ive had this problem on two bikes, squealing rear brake, no power but no signs of leaks. Cleaned rear disc and replaced the pads, all was fine for a week then the problem returned. Had to replace the entire caliper as Shimano dont provide spares.

    I had the same problem so I replaced the discs and pads but this didn’t fix it. I replaced the calipers as it turns out the pistons where sticking in my old calipers and it’s been fine now for a few months. 

    March 20, 2017 at 7:24 pm #889021
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    newtonk

    Same problem here, as

    Same problem here, as mentioned on another thread – I honestly think any bike shop in a flat area selling bikes equipped with these brakes without asking the buyer about their riding style is doing their customers a massive disservice. 

    Using my hybrid to commute in London, it’s just not possible for me to use these brakes hard enough to overcome the squealing or wear in the pads/rotors or whatever else it is you’re supposed to know/do to get brand new brakes on a brand new bike to function correctly and below the decibel levels of a jumbo jet.

    Like many others, when it’s wet I now use my rim brake road bike instead – exactly the opposite of what I intended when buying the hybrid. 

    Buying a new bike for commuting in a flat area?  You might get lucky or you might not, but don’t bother with disc brakes would be my advice.

    March 20, 2017 at 9:07 am #889019
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    IanEdward

    Sorry I meant Shimano had
    Sorry I meant Shimano had been sitting on issue of leaking seals for years.

    I like the ’emperor’s new clothes’ analogy though!

    March 19, 2017 at 9:55 pm #889017
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    CXR94Di2

    I have 5 bikes with disc
    I have 5 bikes with disc brakes, its the compound of the pads. All squeal to some degree. Much less so with sintered pads. I’ve cleaned my disc rotors with brake cleaner after a wet ride and the noise has immediately gone until it rains again. I change my pads to sintered much much quieter.

    March 19, 2017 at 9:49 pm #889015
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    rnick

    It’s par for the course I’m

    It’s par for the course I’m afraid.  Based upon my MTB experience, I used to find braking in wet conditions particularly noisy if the bike had just been cleaned.  Riding through the nearest dirty muddy puddle seamed to fix the problem – so I put it down to a surface “glaze” or similar.  To an extent, disk brakes are the emperor’s new clothes – sure they’re great when they work, but get some oil on the disc / pads and you’re binning the rotor & pad, unlike car  & motorbike brakes, road bike brakes don’t generate sufficient heat to  burn off the oil.   With a rim brake, such situations are often salveagble.

    March 19, 2017 at 9:33 pm #889013
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    Anonymous
    IanEdward wrote:
    The worst thing is Shimano just seem to be sitting on this issue, it’s been happening for years!

    It ain’t just Shimano. Avid/SRAM, Hope, Formula, Hayes etc etc there isn’t a brand on the market that doesn’t squeal when wet. I’ve tried every type of brake compound ever invented, all to no avail. I’m afraid it’s par for the course… just like the noise carbon rim brakes make all the time on a decent descent.

    March 19, 2017 at 6:53 pm #889011
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    IanEdward

    The worst thing is Shimano

    The worst thing is Shimano just seem to be sitting on this issue, it’s been happening for years!

    My dad treated himself to a brand new, flat barred Giant Road Bike with Shimano Hydraulics for his retirement, and never rides the thing as the brakes are just so noisy (oh, and they rub too, despite repeatedly being reset with a Hayes Calliper alignment tool). I’ve just spent afternoon sanding rotors, blowtorching pads, trying to find leaks, cleaning pads, re-installing and trying to bed them in again, and I strongly suspect it won’t have worked.

    I don’t buy this excuse that oil and grease get thrown up from the road either, if this is the case why are the brakes being sold on road bikes and commuters?

    Also, I think the industry needs to give riders better advice on what disc brakes are actually good for, and what not. Commuting being a good example of perhaps when disc brakes are not worth the slightly improved braking response.

    My commuter is cursed with screeching noisy disc brakes in the wet, so much so that I take my far less advanced/expensive rim braked commuter out when it’s wet. Maybe if I commuted through the Lakes or the Cairngorms this wouldn’t be an issue, but since Edinburgh’s ex-railway line cycle paths are all invariably flat I never do enough braking to warm the pads or the rotors up.

    Perhaps the manufacturers need to develop a pad which works despite infrequent use, and doesn’t screech in the wet. Perhaps some sort of compound which doesn’t glaze over and is siped to clear water from the disc. A compound that doesn’t instantly soak up every little impurity out of the spray from the road would be handy too…
     

    March 17, 2017 at 8:42 pm #889009
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    dunnoh

    Try Muc Off Disc Brake

    Try Muc Off Disc Brake cleaners.  It seems to do the trick

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