Australia and New Zealand · Public discussion

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

amirm · 2004-01-22T01:41:40+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 · 22 January 2004 · Last activity 22 January 2004 · 5 posts · 673 views

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Original section: Australia and New Zealand
Published: 22 January 2004
Last activity: 22 January 2004
Original author: amirm
Posts: 5
Discussion status: Public discussion
Total views: 673
Views / 30 days: 0
Topics: Brake squeal Disc brakes Brake pads

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Original post
amirm
Archived post

22 January 2004, 01:41 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, 02:43 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...
http://www.bbc.co.uk/scotland/sportscotland/airtight/mtb/tech_tips/sqeal
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, 08:49 UTC #3

Ok, a lot of disks vibrate on the frame mount which causes noise. It i
like frames have this inbuilt harmonic preset in them
What you have to do to stop vibration related noises.....first, alig
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 hu
tight too
If all else fails, just spray WD40 on your disk, then there will b
vibration related noises..
-

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amirm
Archived post

22 January 2004, 22:51 UTC #4

onegeargimp said:
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...
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.
--

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amirm
Archived post

22 January 2004, 22:51 UTC #5

Hippy said:
"amirm" <[email hidden]> wrote in message news:oTFPb.38-
[email hidden]:[email hidden]-
etserver.com...
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...
http://www.bbc.co.uk/scotland/sportscotland/airtight/mtb/tech_tips/sqea-
lhttp://www.bbc.co.uk/scotland/sportscotland/airtight/mtb/tech_tips/sqe-
al ing_hopes.shtml
Lots of the mtb forums will be able to help:
e.g. www.mtbr.com Techtalks section.
hth hippy
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.
--

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