Disc Brake Squeling

[XTC OKE]

everytime I pull the lever of my rear disc brake it squelches. What can this be??

 

1.Is my rotor contaminated?

 

2.Is my rotor not centered?

 

[Jules]

I think the most common cause of squealing brakes is water contamination in the pads. It might go away after heavy breaking or you could try filing them? Otherwise your rotor might be out of true.

[Dirtbreath]

When my pads give me crap I put some sand paper on a flat surface and rub the pad across the paper. Ensures that the surface is flat which is difficult to do with a file.

 

 

 

[Johan Bornman]

Rotor is American.

Disc is in use in the rest of the world.

 

Your pads are glazed. Do what dirtbreath says and stop favouring your back brake over the front. Dragging the back brake endlessly is what causes the glazing.

 

 

 

 

[Wyatt Earp]

Make sure your ROTOR blade is clean.

[GoLefty!!]

A ROTOR balde is what you find on rotary wing aircraft.....not bicycles.

 

A disc rotor is more common on earth based vehicles.

 

 

Squelching?? Well that could mean anything. I assume Squealing as dirtbreath says.

AS he says the pads are glazed,clean them up. Also when you clean your bike with those lovely paraffin based detergents make sure the disc brake rotors are not near those detergents we clean our precious bikes, the forks an wipe oil that has splattered from the chain, fork, and other bearings all over the bike and onto the disc rotors. During the next ride the pads pick up these contaminants and others and hey presto, squealing brakes.

 

Hence I seldom clean my bike, with detergents.  a Simple brush down, wipe with damp clothe and polish on frame is all thats needed.

[Wyatt Earp]

 

I like my ROTOR blades on my bike.

Also forgot, it's common in turbines.

Summit Cycles2008-12-24 07:44:47

[Wyatt Earp]

 

A ROTOR balde is what you find on rotary wing aircraft.....not bicycles.

 

A disc rotor is more common on earth based vehicles.

 

 

Squelching?? Well that could mean anything. I assume Squealing as dirtbreath says.

AS he says the pads are glazed' date='clean them up. Also when you clean your bike with those lovely paraffin based detergents make sure the disc brake rotors edit. snip over the bike and onto the disc rotors.

[/quote']

Same difference

 

[GoLefty!!]

whereas a rotor blade is completely different.

get over it.

[Wyatt Earp]

I got over it when my first disc equipped bike landed via turbine powered aircraft and they are actually more commonly known as folding rotor blades in a rotary wing aircraft.

 

[Daxiet]

Wow...

 

I have had a couple different sets of brakes pierce my ears, the first bunch was on a Silverback Dakota with Haynes Stroker's both front and rear used to squeak. I tried sanding the pads, the owner of the canary then got the LBS to swap the pads, then tried a new ROTOR. In the end these little puppies would just squeak. Ok, when well washed they would be quiet until the first dirt road, then they would sing.

 

The other set is a Shimano Deore front brake, it is new and can't help but squeak (clean or dirty), I have not yet sanded them down, which may work but past experience makes me doubtful.

 

This all said I think certain combos equal a perfect harmonic distortion of some sort that means they will always squeak.

 

But yes try sanding the pads. It can also occur when the rotor is bent or not true.

 

[Johan Bornman]

Disk brake squeal will probably be solved by new designs in future. On rim brakes we had a similar problem until they started to machine rim brake surfaces. This added some roughness to otherwise smooth surfaces, that remained there throughout the rim's life unless dragged endlessly, as some people do with their rear brakes.

 

Brake squeal is due to stick-slip friction that happens in the audible frequency - in other words, for a perfect high C, this would happen at 768 HZ or put differently, the pad will grip and slip 768 times per second. A brake that doesn't squeal squeals for bats and dogs, we just can't hear it, so who cares? This noise signals decreased braking efficiency.

 

This stick-slip friction can be reduced if we go for harder pads. This will reduce the elastic motion in the pad material which causes the vibration. Unfortunately bicycle brakes are limited by weight and therefore strength and hard pads are out of the question since they would require a brake booster of sorts.

 

Stick-slip friction can also be reduced by macro roughness on the disk, something like the rim's grooves, although it doesn't seem practical at present. I don't know why.

 

Stick-slip friction is increased when heat generated in the pad cannot be effectively removed. Disks are by definition poor conductors of heat, having a small surface area that cannot radiate much, have a small attachment to the aluminium hub and, have to be made from stainless steel - a poor conductor.

 

In this scenario, the pad glazes over, which for some reason increases the stick-slip friction. The best way to remove glaze is to ride through mud and apply brakes. Unfortunately discs are 400mm from the surface and riding through thick mud doesn't appeal to anyone. The next best solution is to remove the pads and wet sand them on 300 grit water paper in a figure 8 pattern. This pattern helps to eliminate hand movements at the extreme ends of the motion that causes you to rotate your wrist and sand them with a convex face. Convex pads don't make proper contact with their discs.

 

The slightest bit of oil seems to promote disc glazing. Even riding through water contaminated by the previous rider's chain lubrication seems to do the trick. Some hubs dump grease onto discs but I suspect most people are just plain sloppy with their chain lubrication and do the evil deed themselves. Spray lubricants are a no-no for disc brake bikes. I also think mere washing introduces oil into the pads.

 

I see V-brakes in my future for a long time to come.

 

 

Johan Bornman2008-12-24 09:12:13

[Johan Bornman]

Aish, the semantics!

 

I actually don't care what people call the circular friction dot on their hub-mounted calliper brakes. I merely observed some cultural differences. I'm sure in India they call it a silver roti and on the Italian islands something like ferrous pizza.

 

However, this thread: https://www.bikehub.co.za/forum_posts.asp?TID=39591  confuses the hell out of me. He's selling rotor rings for his crank.

 

I am confused.

[Wyatt Earp]

I could also never understand why they call them rotor rings 

[GoLefty!!]

....because maybe, just maybe........and I'm taking a long shot here........

 

 

 

"Chain Rings" was already taken...?

[Wyatt Earp]

 

....because maybe' date=' just maybe........and I'm taking a long shot here........

 

 

 

"Chain Rings" was already taken...?

[/quote']

WOW

The name chainrings was taken when Biopace was launched but they were known by their common name as Biopace chainrings.