Australia and New Zealand · Public discussion

Disc Brake Squeal... any fix? (long)

amirm · 2004-01-21T22:25:09+00:00

I recently got a bike with Shimano 525 hydraulic disc brakes. I tried to bed in the brand new brakes when I got the bike by riding up and down a steep road and by repeated braking to almost full stop and riding away again. That seems to have worked well. Now the complaint is with the rear brake making vibration-related noise. First, it sounds worse when tyres (with big knobby patterns) are inflated to max. Second, the higher the speed the noisier it becomes. Third, it happens only during pedalling, and squeal almost disappears as soon as I stop pedalling. Fourth, when the brake is busy making the annoying noise, if I lightly apply rear brake, the squeal turns off. With cars, this type of squeal, especially when going away if brakes are applied, is due to the springs retaining brake pads. I assume that a similar concept is used in bike brakes, too. Does anyone share this problem? If yes, is there any fix? By the way, the bike is over 200 km now, and the rear brake does not make as much noise. Would it mean that it might go away over time? Cheers.

Started by amirm · 21 January 2004 · Last activity 22 January 2004 · 5 posts · 1,278 views

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Original section: Australia and New Zealand
Published: 21 January 2004
Last activity: 22 January 2004
Original author: amirm
Posts: 5
Discussion status: Public discussion
Total views: 1,278
Views / 30 days: 0
Topics: Brake squeal Disc brakes Brake pads

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Original post
amirm
Archived post

21 January 2004, 22:25 UTC #1

I recently got a bike with Shimano 525 hydraulic disc brakes. I tried to bed in the brand new brakes when I got the bike by riding up and down a steep road and by repeated braking to almost full stop and riding away again. That seems to have worked well. Now the complaint is with the rear brake making vibration-related noise. First, it sounds worse when tyres (with big knobby patterns) are inflated to max. Second, the higher the speed the noisier it becomes. Third, it happens only during pedalling, and squeal almost disappears as soon as I stop pedalling. Fourth, when the brake is busy making the annoying noise, if I lightly apply rear brake, the squeal turns off.
With cars, this type of squeal, especially when going away if brakes are applied, is due to the springs retaining brake pads. I assume that a similar concept is used in bike brakes, too.
Does anyone share this problem? If yes, is there any fix?
By the way, the bike is over 200 km now, and the rear brake does not make as much noise. Would it mean that it might go away over time?
Cheers.

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Hippy
Archived post

22 January 2004, 06:09 UTC #2

"amirm" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:
Third, it happens only during pedalling, and squeal almost disappears

as
Quoted message said:
soon as I stop pedalling.
Are you sure it's the brakes then? Maybe frame flex when you pedal is moving the disc rotor onto the
calipers? You should be able to adjust this - I don't have disc so I don't know how, but there are
many websites on this topic.
Quoted message said:
Fourth, when the brake is busy making the annoying noise, if I lightly apply rear brake, the
squeal turns off.
It does sound like the rotor/calipers need slight adjustment...
bbc.co.uksqeal ing_hopes.shtml
Lots of the mtb forums will be able to help:
e.g. www.mtbr.com Techtalks section.
hth hippy

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onegeargimp
Archived post

22 January 2004, 08:34 UTC #3

Ok, a lot of disks vibrate on the frame mount which causes noise. It is like frames have this inbuilt harmonic preset in them.
What you have to do to stop vibration related noises.....first, align the caliper properly. Make sure it is centred and not toeing in or out. Now, tighten all those bolts. Ensure you disk is screwed onto the hub tight too.
If all else fails, just spray WD40 on your disk, then there will be vibration related noises...

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amirm
Archived post

22 January 2004, 22:10 UTC #4

Hippy:
Actually, part of the noise is due to flex. Today while riding I was coasting (no pedalling), so there was no noise at that speed. Then without cranking, I pushed my right foot down and pulled the left one up, and there came the noise! So flex at BB point is a problem.
I think what I have been complaining about had two components: one general squealing (more of a vibration-related noise), and the other flex-related. The vibration-related noise is progressively residing, and if I can adjust the rotor for flex, then my problem will be solved. Thanks for the URLs. I'm gonna try them.
Cheers,
Amir.
Quoted post said:
Originally posted by Hippy
"amirm" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:
Third, it happens only during pedalling, and squeal almost disappears

as
Quoted message said:
soon as I stop pedalling.

Are you sure it's the brakes then? Maybe frame flex when you pedal is moving the disc rotor onto the
calipers? You should be able to adjust this - I don't have disc so I don't know how, but there are
many websites on this topic.

Quoted message said:
Fourth, when the brake is busy making the annoying noise, if I lightly apply rear brake, the
squeal turns off.

It does sound like the rotor/calipers need slight adjustment...

bbc.co.uksqeal ing_hopes.shtml

Lots of the mtb forums will be able to help:
e.g. www.mtbr.com Techtalks section.

hth hippy

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amirm
Archived post

22 January 2004, 22:14 UTC #5

Thanks onegeargimp!
With WD40 on my rotors I'm gonna be REAL FAST in downhills!! 😉
I don't have any experience with disc brakes. Before following your instructions, I need to read some tech stuff so I know how to do the adjustment properly. The long weekend is a good time to do this. 🙂
Cheers,
Amir.
Quoted post said:
Originally posted by onegeargimp
Ok, a lot of disks vibrate on the frame mount which causes noise. It is like frames have this inbuilt harmonic preset in them.

What you have to do to stop vibration related noises.....first, align the caliper properly. Make sure it is centred and not toeing in or out. Now, tighten all those bolts. Ensure you disk is screwed onto the hub tight too.

If all else fails, just spray WD40 on your disk, then there will be vibration related noises...

Report

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