Noisy disk brakes

daviddd

The squeal from my Shimano XT disc brakes on my top-end Focus carbon MTB is unbearable, and it's got to the point where I've practically stopped using it. The noise is huge front and rear and inhibits me from braking properly, apart from scaring people. I'm likely to cause heart attacks. I've read loads of advice about this common problem, and have cleaned everything, sanded the rotor, centered the caliper and wheel, bled the hydraulic system and replaced the pads with Swisstop greens at £20 a pair. I'm holding back from spending another £20-30 on new rotors and even new brake units. This puts me off using discs altogether and going back to rim brakes.

Chunkers1980

Faffing with them seems to cause more issues than it solves. Long hard period of use whatever noise they make usually works.

cooldad

This, especially random bleeding, which has nothing whatsoever to do with noise.

But depends what you cleaned things with. Water is good, and IPA for rotors if necessary.

dgunthor

i put copper grease on the back of the pads between the pad and the piston - it's what's used to stop squealing brakes on cars too

Chunkers1980

Not on bikes it's not. And is a very bad idea.

keef66

Chunkers1980 wrote:

Not on bikes it's not. And is a very bad idea.

Why not?? Apart from size and servo assistance, what's the difference between disk brakes on a bike and a car?

keef66

And if you do get it on the pads / rotors??

http://motorexbicycle.com/mb/prod_detail.asp?id=21

Seems they actually recommend you do just that!

Chunkers1980

keef66 wrote:

Chunkers1980 wrote:

Not on bikes it's not. And is a very bad idea.

Why not?? Apart from size and servo assistance, what's the difference between disk brakes on a bike and a car?

100s of degrees for longer. Holes in the backing can let it soak in to pad material. Pistons which don't like anything else apart from a little fluid coming into contact with them. Size. And there really is no need it'll just attract crap, just use.

kajjal

As you have tried the normal fixes, one that worked for my bike using XT brakes and rotors was loosening off the front hub. Not sure why but was too tight and made the wheel notchy as it span round. Loosened it off so it span freely and no more noise. Also check the headset and all bolts etc on the bike are done up properly.

Other threads suggest it could be some type of resonance which is fixed by attaching things to the frame / calipers. I think the stump jumper fsr suffered from this for some people.

dj58

keef66 wrote:

And if you do get it on the pads / rotors??

http://motorexbicycle.com/mb/prod_detail.asp?id=21

Seems they actually recommend you do just that!

Have I understood the instructions correctly, apply it to the pad and disc matting surfaces? seems bonkers to me.

dgunthor

apply to back of the brake pad

veronese68

DJ58 wrote:

keef66 wrote:

And if you do get it on the pads / rotors??

http://motorexbicycle.com/mb/prod_detail.asp?id=21

Seems they actually recommend you do just that!

Have I understood the instructions correctly, apply it to the pad and disc matting surfaces? seems bonkers to me.

I suppose you could apply it to the mating surface between rotor and hub, but it could still get flung outwards onto the braking surface unless used extremely sparingly. More to the point they really need to word that more carefully. :shock:

keef66

"Fixes squealing mountain bike disc brakes. Apply the paste directly to the rotor and pads. Copper Paste will not harm the brake action and remove the squeal. "

Seems they unequivocally recommend application directly to the friction surfaces :shock:

I wouldn't be trying that for the first time on a black run though.

Happily I don't have this dilemma being a roadie with effective rim brakes and no big hills to descend

Chunkers1980

Pootle off then

dj58

"Application Notes
Fixes squealing mountain bike disc brakes. Apply the paste directly to the rotor and pads. Copper Paste will not harm the brake action and remove the squeal."

That is exactly my point, someone with little or no experience of disc brakes could interpret that to mean apply it to the working surfaces! Needs to be more explicit.

Apply the paste sparingly, directly to the rotor/hub mounting face and the rear of the brake pads only.

Chunkers1980

Still an awful idea.

The Rookie

Ruddy stupid idea...as above, many backplates are not solid so the grease can soak into the back of the pad though the hole.

Don't sand the rotor, lightly sand the front of the pad, what pad type are you using, metal are worse for squeals than organic, make sure the calliper is aligned properly and all bolts tight.

If it's a constant pitch noise, changing volume, it's a resonance, if it's not a constant pitch noise it's likely caused at the friction interface.

daviddd

Thanks so far, I've done all that (not greasing back of pad though). I did wonder if a bit of play in the wheel bearings might be detrimental.

kajjal

daviddd wrote:

Thanks so far, I've done all that (not greasing back of pad though). I did wonder if a bit of play in the wheel bearings might be detrimental.

You could briefly swap the front wheel for someone else's who has no problems to see if it stops the noise.

daviddd

I'm using Swisstop organic pads...still howling.

The Rookie

Play in the bearings won't help.

What type of squeal as per earlier Q?

daviddd

Yes, constant pitch, very loud...a parrrppppp!

The Rookie

Par RRP sounds like an issue with the slots in the disc which could be related to your bearing issue...

daviddd

I was wondering if I need to replace the rotor. And the flippin' hubs. Hmmm, maybe buy a new bike...

Chunkers1980

What? Fix the wheel. Cracking idea, buy a new bike rather than do something up....

kajjal

Chunkers1980 wrote:

What? Fix the wheel. Cracking idea, buy a new bike rather than do something up....

Get spanners and sort the hub out, it won't take more than few minutes. If your desperate get your local bike shop to do it.

Mattharrier

Chunkers1980 wrote:

What? Fix the wheel. Cracking idea, buy a new bike rather than do something up....

To be fair, he can buy a new bike, then get the issue resolved on the current bike, and then he has an extra bike! N+1 and all that

daviddd

Ok, will maybe have to replace front hub ... but I would really love a Stoater Rohloff with belt drive, a great Scottish bicycle. http://www.shandcycles.com/bikes/stoater-rohloff/

Angus Young

daviddd wrote:

... but I would really love a Stoater Rohloff with belt drive, a great Scottish bicycle. http://www.shandcycles.com/bikes/stoater-rohloff/

Why are you in the mountain bike section?

Chunkers1980

Scotland has loads of mountains confusing him?

daviddd

Angus Young wrote:

daviddd wrote:

... but I would really love a Stoater Rohloff with belt drive, a great Scottish bicycle. http://www.shandcycles.com/bikes/stoater-rohloff/

Why are you in the mountain bike section?

Because I like mountain biking, and touring, and ant activity involving bicycles. Is that abnormal then?