Intense Brake Squeal!
 

Hi guys,

I installed Carbotech AX6 brake pads 10k miles ago and I don't think I did the bedding process correctly (I applied ABS, and only did the 0-60-0 about 6 times and there was probably 2 min between each 60-0. Long story short I have a horrible squeal and what sounds like pads rubbing when I'm not even on the gas pedal.

My question is what is the best way to eliminate this noise? Can I try to re-bed my brakes, or is the original bedding layer already gone and this would be futile? I have removed the brake shims.

If the pads are toast I assume I would new pads, but would the new centric rotors be ok?

This has been bugging me for a while so any and all help is appreciated!! I also would be looking for pad suggestions that are less intense than AX6.

Re-bedding should fix it for a time - repeat as needed. It won't be permanent, but can last quite some time if you get the procedure right for the setup you have. Are they quiet for the first few stops? Or are they always noisy?

I haven't yet found a procedure that gives me more than a handful of quiet stops. Mine are quiet when cold, though. The procedures that are recommended are impossible for me to do without quite a long drive, and I never think of it when I'm already somewhere I could try it. Some day.

C

Okay first I would inspect your brakes thoroughly and try to find if there is a more serious issue behind the noise you are hearing. Is this noise occurring only when doing a certain thing with the car? (Under braking, when turning, etc) A recording of the sounds would be great too if you're unsure if the cause of the sound is actually just the pads needing bedding.

You also have to regularly bed brake pads. The transfer layer goes away over time.

You should regularly inspect your brake pads & calipers anyways. You'll be fine if you swap pads but reuse the rotors. You'll have to bed the new pads obviously.

They're only noisy at lower speeds, and sometimes I can press the brake pedal slightly more and the noise just goes away completely as long as I keep that specific pressure on the brake. Mine also don't squeak when it's cold, and I have tried to the re-bed procedure multiple times but sometimes the noise comes back after days. I guess I just need to do more 60-0s.

Thank you for your input.

I only hear the brake rubbing noise when I'm driving straight. I have noticed that when I re-bed the noise goes away for a while, but it'll eventually come back. Should I be braking more during low speed daily situations? I tend to engine brake and maybe that causes the transfer layer to go away quicker? I also do about 20k miles per year so I am driving a lot in daily situations. Thank you for your input.

From what you're saying the pads sounds normal. Even with bedding when pressing gently/lightly on the brakes there's a bit of noise. I just live with it because braking harder is going to spill my coffee everywhere when I'm driving on the street lol

After 10K they should be bedded fine even with regular driving. You say they are noisy even when just driving and not on the pedal? Is it all the wheels? One or more pads are just loose?

It's an autocross oriented pad and everyone I've talked to says it's on the noisy side. Where there is inconsistency is in how long people get them to be quiet. I can think of a few that gave up on the pad because it didn't meet their 'street and autox' needs well due to the noise.

C

I'm thinking it's the front brakes that make the whisking brake noise when I'm driving normally. And I checked all bolts for tightness about 5k after the install and everything was fine.

I think this all might be normal for the pads as I wasn't thinking when I ordered pads that were partly made out of metal lol. If I could choose again I'd go with a less intense pad.

That makes sense, I think this is just a case of me buying too much pad for what I would use them for. They do feel great when they are hot though!

You experiencing colder weather lately? Cooler weather and high performance pads have the effect of squealing.

Try putting the shims back on. It made a world of difference on my Project Mu HC+ 800 pads.

That is sort of what I was getting at.

Also, nobody mentioned brake grease, but did you use some? You need to put that stuff between the pad and the shim, and between the shim and the caliber and also on the retaining clips. This help a lot with the squealing. Use something high quality. Obviously make sure you don't get any on the pad surface and on the rotor

Yes I did use grease but not on the retainer clips. I’ll order new shims.

Do I have to cake both sides with grease or can I leave the exposed part of the shim clean so it doesn’t make it look bad?

I think you need grease on both side. You don't really need to have grease on the part of the shim that is exposed to the air, but it would help to have some on the part of the shim where the caliper is squeezing.

Ok good to know.

And I’m about to order new shims, do I need the rubber shims as well? The car is mainly used as a DD.

Rubber shims? You got a pic? Are you talking about the dust boots?

On #7, right inbetween the pad and the shim. It was a soft shim of some sort.

https://i.imgur.com/w7XkPPN.png

Ah I see. I never noticed since I didn't look at my stock pads. Replaced them early on.

Brake noise or squeal when the brakes aren’t being pressed is not right. Something is sticking to cause the pad to rub that much. If you are just getting squeal when you barely depress the brakes, or under light braking at slower speeds then all is good and welcome to the world of performance brakes.

Jut an update:

Did the bedding process again and the whisking brake noise is gone.

Brakes still squeak, but sound more normal than the banshee noise that was there before.

Thanks everyone for the help! I’ll be able to make a more informed pad choice next time.