Noise from Brake Fluid Reservoir - Buzzing? | GTAMotorcycle.com

Noise from Brake Fluid Reservoir - Buzzing?

S

starlifek

Active member
Hey guys,

Today I noticed some noise coming from the front brake fluid reservoir while applying the front brake.
It's like a high-to-low pitch buzzing sound as it slows down.

I have no idea what this is, I'm not sure if this is any related, but I lowered the handle bar and the reservoir sits in a bit of an angle.

Any idea guys?
 
Could it be air getting in and out of the reservoir?
 
I'm not sure. It only makes the noise when brake is applied, and it sounds like ZZZZZZzzzzzzzz as it slows down.
It's definitely from the reservoir though.

If you are right, is it normal to hear air getting in and out?
 
starlifek said:
If you are right, is it normal to hear air getting in and out?
Click to expand...

Not normal. As a matter of fact, the reservoir has a rubber diaphragm inside to prevent air from getting in. Air contains moisture, which gets absorbed by the brake fluid. The moisture may cause steam bubbles to appear in high temperatures and reduce the fluid's ability to transfer pressure from the master cylinder to the calipers.
 
I'm gonna replace the brake fluid and see if this changes anything.
I suspect there could be some air bubbles in the brake lining, probably need to bleed it.

I'll keep you guys posted.
 
starlifek said:
I lowered the handle bar and the reservoir sits in a bit of an angle.

Any idea guys?
Click to expand...

Another guess: the fluid level is a bit low and the air that is already in the reservoir gets sucked into the master cylinder.

All of this is just guesswork. If you can hear this noise while the bike is parked, take the cap off from the reservoir and try it again.
 
I wonder if it's coming from the rotors.

Some other forums have similar posts where they say it's from the drilled rotors.
My bike only has a single rotor on the right side of the bike, which makes sense if I am misunderstanding as noise from the reservoir(which is also on the right side.)
 
starlifek said:
I just gave up. It's not affecting braking performance so I deem this normal now.
Click to expand...

If you have enough air bubbles in the system that you feel they are making noise, I dont think the brakes would work worth a s**t.
I think its the rotors on the front making the sound you are hearing.
My son's GSX 650 F front rotors make this buzzing sound when applied but that is normal and due to the rotor design.
If your close to Oakville let me know and I'll take a look at it for you.
 
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