Modest braking sounds similar to squealing tires

Question

When I'm braking at a stop sign, I'm hearing a sound that sounds like a high pitched tire squeal; it's like a mix between tire squeal and the constant chirp from a bad belt, and it's coming from the front of the car. I believe it's coming from both sides.

At first thought it seemed obvious that it was the tires, but here is my list of thoughts:

• Tires are high-end, nicely broken in, yet still have plenty of tread, so maybe it's the brakes?
• On the other hand, the brake rotor have only the slightest (1mm, 2 at most) groove and the pads are still at least 1/4" and none of the sensors have come on.
• This only happens when the car is warmed up (which should make the tires grip even better, right?)
• I tried this in neutral and the noise still happens, so it's not the drivetrain
• This only happens just before coming to a stop, even with modest braking. I've slammed on the brakes when going fast and I don't get the sound
• I've heard it could be something stuck on the pad, but I don't see any strange grooves on the rotor
• The sound is only for a second

What could it be?

Answer 1

tl;dr The sound is probably caused by your brakes, most likely worn brake pads.

Firstly, you would only hear "tyre squeal" if the vehicle is losing (or at least scrabbling for) grip during the braking period. If that's the case, you will know it's the tyres! That takes a lot of braking force, and not likely something that will happen casually. So, I would say it's certainly the brakes.

If you are absolutely certain that you're not hearing the "low brake pad" warning made by the steel warning point against the disc, then it might be your pads have shaped in such a way as to cause the noise. Do you do lots of highway driving?

One thing you could try to remedy the shape of the pads (which is a microscopic change) is to find a safe, uninhabited car park or stretch of road (tarmac). Reverse the car, and gain a bit of speed. Once you're going at 15-20mph, brake moderately well to bring the car to a complete stop. Go forward and reapeat about 5-10 times.

This procedure will help to shape the pads so that they are not point-contacting the disc, but so that more of the face of the pads engage with the discs.

Alternatively, you could buy some very inexpensive brake grease (yes it's a real thing) from your local part store or garage and squeeze that onto the discs. It's designed to reduce noisy brakes.

Lastly, if the vehicle is braking unevenly (pulling to one side or other) get it checked out by a professional - your brakes are too important to leave to chance! All the best!

Answer 2

what i get is that it might be some clip that holds the brake assembly coming in contact with something when u brake moderately.

Happens when car is warm--->temperature increases the metal clip/strip of brake assembly EXPANDS like it was 7 mm it expands to 7.2 mm comes in contact abrasively with other parts.

on slamming brakes hard u dont get the sound right? Maybe because the bads or the assembly moves deeper towards the rotor/discs and hence the gap betweeen clip/strip increase so no contact occure, while on moderate braking the bads are not depressed much and the expanded/displaced clip/strips touches the bads or any other part because of which u hear the sound.

Might be because ur front suspension had been to a hard jerk on a bump.