Front break buzzing when squeezed (ST1100)

Afan

... and this is my real name.
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Two weeks ago I replaced front break pads and changed the break fluids. Went ok, without any problem.
Recently, maybe week ago, I start hearing a buzz every time I use the front break, even the slittiest squeeze. It's a tiny buzz, nothing loud, but easy to hear. On lower speeds not so much, or not at all. So I wonder if I did something wrong while bleeding the break fluid in front break, or while changing the pads?


Thanks for any help.
 

Firstpeke

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It may help to chamfer leading edge of the pads, which is of course the back edge due to wheel rotation......

This helps reduce any catching on the holes in the disc, of course I am assuming you have checked for any damage or items trapped in the disc or caliper!
 

ST1100Y

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In addition to Firstpeke's suggestions I also need to ask if the calliper pistons were moving freely during the pad replacement, or if some seizure becomes apparent...
Dragging pads might heat up and suffer glazed, thus harder surface, which is then "buzzing" on the edges of the disk holes when you apply the brakes...

While going aggressively, like hunting squids through the twisties, a barely audible whirr is emitted under heavy braking, partly origins from the holes in the rotors, partly from the thread pattern of the tire on the road...
 

ST1100Y

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Can't prove that the partially delaminated pad caused the noise as I did a lot of cleaning, lubing, etc...
I do hope you binned the suspicious pads right away, I'd be very concerned... never saw such with OEM pads though... squeaking maybe due no coper slip on damping plate...
 
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I'm betting that 'binned' in Australia has exactly the same meaning in Austria!
:D
I seem to recall back in the '90s Martin made the comment that Americans would sometimes interchange Austria and Australia.
 
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I also have this buzz on the front brakes. It's there when lightly applying the brakes but goes away when more braking force is applied. I always thought this was some sort of high frequency vibration that begins when the pads are pressed into the rotors. With more force applied, the vibrations stop. Try high temp brake lube on the back of the pads and see if that makes the buzz go away.
 

ST1100Y

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No vibrations here, but can create a buzz or hiss... like where the (mountain) road goes directly aside a wall I get a distinctive noise echoed when grabbing the stoppers...
Seems normal to me due the perforated rotors...
Vibrations however qualify a research to circle down and eliminate the source of trouble... tire cupped, rotors warped/unevenly worn, etc... could be as simple as a worn wheel-bearing...
 

moddy

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I wrote about this in another brake buzzing thread and have an update from a front caliper piston extraction and cleaning 2 weeks ago. After multiple times of making sure the brake master cylinder would not lose fluid while bleeding air from the system, my wheel would not spin much more than 3/4 around before coming to a halt.
I ordered new caliper seals for the front brakes (would have just ordered all 3 sets at once because my rear caliper uses the same, but I didn't know.) Watched a youtube video for brake piston extracting while on the bike, cleaned the non-pitted pistons and cleaned the grooves where the new seals go.
After I bled the air from the system again, the wheel spun around 2 to 3 times, because I believe the calipers were not able to retract as much as they should with the older seals and dirty caliper pistons. A further observation of of old seals vs new, the older ones were about .5mm taller when compared, leading me to believe the slight bit of swelling clamped onto the pistons for their proper function. Result, no more buzz while riding and not braking, slight buzz remains on brake handle contact.
 
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Afan

Afan

... and this is my real name.
Joined
Jun 2, 2014
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Location
Urbandale, IA
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1998 ST1100
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8832
I still didn't figure it out. But the car mechanic was a little bit suspicious about the rotors on the front wheel. According to him, the rotors are not perfectly smooth and new pads I recently put are "breaking in", "adjusting" and soon the buzz will go away.
Though, cleaning front caliper pistons sounds as a very good idea. At least I'm gonna learn something too. :)
 

moddy

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At least I'm gonna learn something too. :)
That being said I will arm you with this video. It's the same one I watched, other videos can be helpful too. I didn't remove the caliper from the bike, because you can use the hydraulic pressure on your bike. Do your best to get them extended simultaneously and as soon as they're close and hang out at a slight angle, you can pull them out with your fingers, this is where the bucket was already placed underneath because the brake fluid with pour out. Handy when it's a brake fluid change anyway. Clean the pistons with something other than metal, or will change the surface smoothness of your pistons. If they're not pitted as mine weren't, and you're caliper surfaces are smooth and aren't pitted, you're good to go. Other than bleeding the air again, it's a gratifying maintenance to accomplish. I even sprung for rebuilding my '91 brake mastercylinder with about a 30.00 rebuild kit from Ebay, that we easy to do too, but that's another youtube video.
https://www.youtube.com/watch?v=Mz1o-1lqzi0
 
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