Modern Vespa

I hear a scraping nose from the rear wheel area when I apply the brakes that occurs whether moving or standing. It occurs with a light touch on the left handle and a heavier touch on the right. It's intermittent; sometimes I don't hear it for days, then it comes back for minutes or days.

Naturally it did not make the noise when I took it to the mechanic; he checked and cleaned everything he could think of. The brakes are fine. Since the service, the noise occurs less frequently, and goes away after a few minutes, but something is still the cause.

I can't determine any rhyme or reason for it. Sometimes the noise occurs on startup; other times it starts in the middle of a ride. Ambient temperature seems to have no bearing. The only consistency is that it occurs only when brakes are applied and it is more sensitive to the left brake handle than the right. There is no difference in the sound whether the bike is moving or standing, and I can't perceive any effect on the operation. It's just disconcerting to hear it.

Any thoughts?

Pretty normal for disc brakes. FAQ: Why do my front brakes make a whirring / cricket sound?
If you also hear them rubbing when no brake is applied that is normal too.

what kind of brake pads are you using?
stock organic?
HH sintered?
brand?

You can hit them with some Sand Paper, but over time it will start again.
Just verify your not metal on metal.

Keith,
Marietta, GA

So, sitting still, you can apply the brakes and hear a scraping noise?

Yes, that's correct. It makes no difference whether I am moving or standing still. Sometimes the noise is there, sometimes not, in both situations.

I don't know if scraping is the right description, it could also be described as whirring, there must be some kind of moving part that is affected by applying the brakes.

A couple of theories have been brought up in the past:

1. Squeezing the brake levers carries more vibration from the engine through the brake pads and the levers, through your hands to your head, and you perceive it as noise from the brakes.

2. Applying the brakes turns on the brake light. That puts a small additional load on the engine which changes the resonant frequencies that you hear.

My car with ~250,000 miles on creaks and groans, pops, and generally makes old man noises when I apply the brakes, even at standstill. I'm thinking rusty/rough sliding surfaces on the calipers, rough or sticky caliper piston, or uneven brake pads that move on the disc as pressure is applied. None of which really worries me as it stops fine.

There is no question about the noise--it is very obvious when it is there and when it is not, and not a resonance frequency.

The bike has less than 5000 miles on it, and brakes were checked two weeks ago. (Front pads were changed last year.) The noise is loud enough that I'm self conscious about it when stopping at an intersection.

Does it sound like this?

Hmmm it won't play when I embed. Just copy what is between the parentheses.

(https://www.youtube.com/watch?v=o_2ZUp8-BgU)

It doesn't sound exactly like that, but it's in the ballpark. There is definitely a sense that it's a moving or motor-driven part, perhaps something that makes contact with a surface when the brake is applied. The mechanic initially thought it might have to do with the clutch, but that all checked out OK.

Does your MP3 have abs?

No ABS. Appreciate all the detective thinking!

No problem. I like a good mystery. Hoping some of my questions will spark someone who has messed with the brakes on these things. Like a power brake booster vacuum or something.

post a video with audio

Good idea. I'll have to wait for it to do it again--it's been less frequent since the bike was serviced, making me think that something he did helped.