Rear Brake scrapping noise

Dear FJRForum,

I hear a noise coming from my rear brake even when it is not engaged. It is louder when I do use the brake, but it is constant. It sounds like there is something in there, but I can't see anything. I can't hear it with helmet on.The brake stops the bike well enough, but can't tell if my stopping power has changed because it was always like that. I didn't bring a helmet when I bought it (didn't think the wife was gonna talk me into it). The bike is 700 miles new so I am not sure if it is just balancing out. I searched for this issue but I didn't see it in the tech forums. Any advice?

Nervous with a Noise

A slight "hissing" sound is completely normal when you spin the wheel; it's due to the brake pads laying up against the rotors. The front wheel is the same way.

Can you elaborate on your "scraping" sound a bit more?

Feej brakes are noisy if you've never had a bike that used sintered pads-if I ride sans helmet I'm still surprised at the amount of noise the brakes, especially the front, generate with the binders on. Grinding is a different story-there are cases where a rock or other foreign material got caught in there, and started eating up the rotor. If this is the case (grinding), get it checked or pull the rear caliper and examine now.

I guess it could be a hissing. It sounds like metal on metal and is higher pitch the faster I go. If the brake pads are supposed to lay up on the rotor then that might cause it.

This is my second bike and the first was a Yamaha XS1100. It didn't make noise, but I don't know if it had "sintered pads". <- gonna go look that up.

DrSticky said:

I guess it could be a hissing. It sounds like metal on metal and is higher pitch the faster I go. If the brake pads are supposed to lay up on the rotor then that might cause it.
This is my second bike and the first was a Yamaha XS1100. It didn't make noise, but I don't know if it had "sintered pads". <- gonna go look that up.

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It didn't. Sintered pads have bronze fibers embedded in the pad material for strength, increased friction, and heat fade resistance, and give the pads their characteristic coloring.. They are a relatively recent pad design, as opposed to the organics used when the XS was born, and are a big part of the reason the brakes on modern bikes work so well. Also, all modern disc brake systems have the pads always in light contact with the rotors, so that piston travel to hard contact is minimal. Most calipers are designed so that the piston seal causes the piston to back off after application very slightly so as to have just the right amount of clearance to prevent hard contact with the rotor, so as to increase mileage a tiny amount, but not so far so as to give the impression of a lot of pedal travel when applying the brakes. Bikes, with their short lever travel, do not, I believe, incorporate this design, so that the pads are always in light contact with the rotor, giving the characteristic "swish" sound when riding.