Squeaking noise from front brake

tmho

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351
Location
Richmond, BC, Canada
My friend's bike got squeaking noise from the front hydraulic brake. The noise appears when you push the bike forward and pull the front brake lever. When riding slowly and pull the front brake lever, there is no noise. I did not try it at high speed because I am afraid that will be very dangerous.
I have replaced the brake pads and tried with another wheel, but still have the noise. I have checked and tightened all the bolts/screws of the brake. What will the possible cause of the noise? Will the noise not coming from the brake?
 
I'd clean the rotors really well first since it's easy and a common cause for squeaking. Like really well. Brake cleaner is nasty stuff but damn does it work well. You did say you swapped the wheel which would presumably mean the rotor as well, but it could be both rotors are dirty.
 
Maybe having weight on the fork dampens it enough to prevent resonance. Is it a suspension fork?

I agree with cleaning the rotor. Don't forget eye protection. I never remember, but a latex/nitrile glove is probably a good idea. That stuff is caustic. Won't help if the pads are glazed over though.
 
My bike made a similar noise before. It took me a bit to find it. I thought it was the rotor or caliper. I isolated the noise, by touch, to the hub of the tire. Outside of both sides of the hub, there is a rubber bushing/washer. It had dirt and grit in there causing the noise. I got the tire off the fork and pulled the quick release skewer from my front tire. The rubber is on the outermost point of the hub. I was able to pull the rubber bushing from the hub and clean it all up. I used isopropyl alcohol then when that dried and I wiped it dry, I put a bit of grease in there. Noise went away. Do you have a picture of your front hub? Rotor side or other side?
 
Except the problem description referenced brake load, and squeaks caused by friction between hub body and dust/grease caps are unaffected by braking.
 
But the squeak is associated with the speed of the wheel turning. Brakes will change the speed of the wheel turning. I thought my brakes were the issue when I had a squeaking. Since the rotor, caliper, and dust caps are all in the same spot, only when I lightly touched the dust cap and turned the wheel, I was able to feel the vibration when the squeak was audible. The squeak happened right at take off, so low wheel speed.

What was strange was, the squeak appeared after I took the front tire off (for a reason I can’t recall) and then put it back on.

It is a low chance that 2 different wheels would have this problem, but if the rotors, calipers, and pads have all been addressed, this could be the issue. So I figured I’d mention it.
 
It sounds like the OP is primarily more concerned with safety than noise. Cleaning the disc and pads provides visual inspection of the parts and if the noise issue is resolved, eliminates that concern. Similarly if the noise comes from a bushing. I’d probably check pads first since it happens on two different wheels, so dirty rotors or the same bushing issue on both is a little less likely, but not out of the question.
 
My friend's bike got squeaking noise from the front hydraulic brake. The noise appears when you push the bike forward and pull the front brake lever.

Disc brake pads and rotors are easily contaminated, especially by hydraulic brakes that provide their own contaminant.

Rotors can be cleaned, but pads are absorbent, so if they become fouled with hydraulic fluid, they usually must be replaced. But replacing the pads will not correct hydraulic leakage if that's what occurred.
 
Thanks for all your comments and sorry for the late reply because I was busy.

I think I need to tell what I found in more details. I did some more tests this morning. Here what I found.

Bike A:
My friend's bike with hydraulic disc brakes. Front brake is making squeaking noise when I push the bike and squeeze on the front brake lever. I had cleaned the rotors and pads with alcohol. I had sanded the pads with sand paper. I replace the brake pads with the ones from bike C. I tried using the front wheels from bike B and bike C. I still get the noise. Please refer to the attached video and photo.

Bike B:
My bike with mechanical disc brakes. There is no similar noise even with the front wheels from bike A and bike C. Please see the attached video.

Bike C:
My bike with hydraulic disc brakes. I found that it has similar noise even with the front wheels from bike A and bike B.

When riding, I do not find the noise. May be I did not brake very hard only on the front brake at high speed because I am afraid that I will be thrown over the handle bar.

Bike B has no such noise. I have changed the settings of the suspension, and still no such noise.

Bike A with Bike A wheel and Bike C brake pads
Bike A with Bike B wheel and Bike C brake pads https://youtu.be/T6zNUgy1cOg
Bike A with Bike C wheel and Bike C brake pads
Bike B with Bike A wheel and Bike C brake pads

IMG_9945a.jpg
 
My bike made a similar noise before. It took me a bit to find it. I thought it was the rotor or caliper. I isolated the noise, by touch, to the hub of the tire. Outside of both sides of the hub, there is a rubber bushing/washer. It had dirt and grit in there causing the noise. I got the tire off the fork and pulled the quick release skewer from my front tire. The rubber is on the outermost point of the hub. I was able to pull the rubber bushing from the hub and clean it all up. I used isopropyl alcohol then when that dried and I wiped it dry, I put a bit of grease in there. Noise went away. Do you have a picture of your front hub? Rotor side or other side?
I think I understand what you mean. I had the problem in the rear wheel of my bike. SQUEAKING NOISE is the post I asked for help. And I solved the problem with Chalo's help.

But in this case, it seems not the same. But I will try it when I have time later.
 
If there are not obvious equipment issues (poor quality, worn, bent, abused, overheated, misaligned, etc.) than the squealing is often caused by grease or oil contamination. Practice good disc brake hygiene! Here is some helpful reading material for you:

 
If there are not obvious equipment issues (poor quality, worn, bent, abused, overheated, misaligned, etc.) than the squealing is often caused by grease or oil contamination. Practice good disc brake hygiene! Here is some helpful reading material for you:

Thank you!
 
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