Squealing Brakes

[groberts]

I've had my Trek 830 MTB for many years, converting it to an e-bike a few years ago. It still rides very well but by now is a bit like 'Trigger's brush' - many of the components changed over the years. Notwithstanding, the cantilever brakes are original albeit with new pads / cables etc. but in recent years the rear brakes have started to judder and squeak very loudly when used (always at the start of a ride, which sometimes improves during a ride.

I fitted a new back wheel couple of years ago, partly to try and rectify the problem which existed with the old wheel, but with no success. I've also changed the pads a couple of times (using Kool Stop pads), ensuring they're properly fitted / aligned and often clean the rims, again with no success.

Any ideas what I can do to stop this, it's often so loud it's embarassing, as well as unpleasant.

Graham

[Jdsk]

Do you know about toe-in, and how much are you adding?
https://www.sheldonbrown.com/rim-brakes.html

Jonathan

[cyclop]

You,ve done all you can.......bar replacing the cantis whose bearing surfaces could be worn.Have you removed,cleaned and regreased these,might make a difference.

[audaxjk]

Ensure that the pads are toed-in. That usually is the cause.

I know it's not helpful but I can't help being mischievous here - your query did remind of a similar issue on my wife's bike in the past - she suggested lubing the brake blocks!!

[groberts]

Thanks but I understand and use toe-in and the pads are clean (new), which is why I've run out of ideas.

[rjb]

Ive cured squeaky brakes on the tandem by cleaning the rims with (god forbid) WD40. It does work despite what most would roll their eyes at in shock. Heres an old post from the expert

One of my former clubmates used to clean his rims with WD40 (which leaves an oily residue) and I used to think he was mad. But having tried it myself I found it worked quite well....so now, I don't jump to conclusions about this kind of stuff...

cheers

[audaxjk]

To RJB

You learn something new everyday! I'll have to eat humble pie and tell my wife she has a point.

[chris_suffolk]

One of my former clubmates used to clean his rims with WD40 (which leaves an oily residue) and I used to think he was mad. But having tried it myself I found it worked quite well....so now, I don't jump to conclusions about this kind of stuff...

Dirty rims is a definite possibility. Try very fine (like 600 grit) wet and dry or a fine wire wool - both work well with a little meths as a lubricant.

[Bullseye]

I had the same problem with my bike, I took the brake pads off an rubbed them down with a bit of sandpaper. I then cleaned them with some surgical spirit and cleaned the rims as well.
I must admit to now inspecting the pads more frequently and also cleaning the rims more often, seems to be working for me.

[gregoryoftours]

As your brakes are original the bushings or less likely the canti studs themselves may have worn enough to cause squealing frequency vibration. You can try wrapping the studs in PTFE tape, surprisingly doesn't affect the pivoting action. If nothing else works it might be time for new brakes. Preferably ones that don't pivot directly on the studs but on a sleeve that's a part of the brake itself.

[PT1029]

Probably worn brake bush in the brake arm, as mentioned up thread.
As a check, put an allen key in the bolt that clamps the brake pad stud (don't loosen the nut), and waggle the allen key in such a manner to increase/decrease toe in (keep the nut tight, you are just wobbling the brake arm on its pivot). This just gives you an idea of how much movement there is.
What I have found sometime works is.
1. Toe the pads in to what you think is ok.
2. Repeat the wobbling with the allen key as mentioned above in a manner to decrease the toe in (so in your photo, put the allen key in, and push the allen key towards the rim, the nut is still tight).
3. Look at the pad/rim interface in stage 2. If the pad is toed out or parallel to the rim, loosen the nut and increase the toe in.
4. Then repeat stage 2 until the pad looks toed in while you are trying to toe it out with the allen key.

Sometimes the toe in looks excessive, but most of that disappears in the pivot wobble/flex when you put the brake on.
If the pivot is very wobbly, the above is a means to an end to avoid the better cure of new brakes.
The brake in your photo looks like a cheap plastic over steel 1990's Shimano (which despite appearances are quite reasonable). I had such noise issues with a set of these not that long ago, and the noise more or less solved.

[francovendee]

I had the same problem and tried everything suggested to me. At best partial success, noisy but I managed to live with it.
In desperation I changed the brakes also the brake pivots on the frame.
I can't say which was the cure but the delight in stopping in silence it was worth doing both.

[groberts]

Many thanks for the thoughts - I'll certainly try the WD40, which sounds counter intuitive + also suspect the bushes, so will pay more attention to them as suggested.

Graham

[PH]

New bike time!
Or, as others suggest, you could try some different brakes, I'd go for v's, a brake and lever needn't cost much, or if you want to try a different canti I might have something in the spares box you could try, as will others.
I'm no expert in these things (Resonance?), sometimes a combination that's working fine becomes an issue with a single change of component.

[MikeDee]

If you can't solve the problem with toe in and cleaning, change the brand of pad. Koolstops are good but do have a tendency to squeal. Disco brake pads are good, but don't know if they make a pad with unthreaded studs.