[Evil Derboy]

My car has Carbon Ceramics and I've been plagued by brake squeal from the get-go. I wanted to post this up in case it helps others who have been experiencing the same issue and have struggled to find the cause.

It's well-documented that BMW M brakes (whether steels or ceramic) are renowned for making noise. BMW has made videos and your dealer will hand you a leaflet specially made to "educate" you.

My issue has been that the squealing on the brakes happens when I'm not braking. I posted a thread about this earlier this year, but felt a new thread may be more useful for those searching Google for a solution.

I'd read lots of conflicting info on CCBs specifically:

• That you should not apply any lube or ant-squeal paste (BMW)
• That you should actually apply some lube for cars that are 48 months old, or older (BMW Parts Catalogue)
• That you need bed the brakes properly (various youtube videos)
• That you don't need to bed the brakes at all and should drive gently for the first 600 miles on a new car, or one that has just had new pads or discs fitted (BMW)
• That you should apply Porsche anti-rattle shims (this forum)
• That you should drive the car hard regularly.

I've tried all of the above on the front brakes as well as changing the pads. Nothing cured the problem. In fact trying to re-bed the brakes actually would make the problem worse. Rather than be an issue when the brakes were cold, mine would get worse as they heated up.

The squeal would disappear and return at random for varying periods of time regardless of all of the above. BMW said that everything looks normal and pointed me to the same well-worn "functional brake noise" argument. I really don't mind functional brake noise. I generally enjoy the car for what it is and so regularly drive it hard, so "functional brake noise" isn't an issue.

On Friday after finally getting round to getting a tool to disengage the electronic parking brake, I decided to have a look at the rears. Now, I'd pretty much dismissed these as being the issue, given that the general consensus is that they don't really do much compared to the fronts and that as I'd experienced constant squealing when turning right at low speeds that it must be related to the fronts as those wheels actually steer.

However, having completely ruled out everything else, I thought, as a last resort, I should rule these out too.

On examination the brake pad material has plenty of life left in them, around 15mm. But the backing plates were a different story. All of them were pretty rusty and corroded. In particular the right-hand, rear-inner pad was solid and I had to use a hammer and a screw driver to release it from the calliper.

I also found a fair bit of muck in and around pistons as well as the textile material on the back of inner pads being pretty chewed up. The lugs that locate into the silver shims on the caliper were particularly corroded.

I got rid of all the corrosion by using a wire brush and applied anti-squeal to the pads and since then, on multiple trips my car has been silent, on the brakes and off.

So the moral of the story here, is that if you're suffering from badly squeaking CCBs (or M compound brakes) don't assume that your issue is down to "functional brake noise". Although the (CCB) pads may last forever, the metal backing plates will still corrode over that time and it's well worth looking at these, especially on the rears, due to it being a floating calliper. If the pad isn't retracting properly when things heat up and expand, that could be the squeal that you're chasing.

The constant loud squeal at in-town speeds had gotten to the stage that it was starting to ruin the car for me and everybody was telling me I just had to put up with it. Dealers seem to have gotten to the point where they just roll their eyes and say "it's normal" without fully investigating the issue, but in my case CCBs have been a red-herring. The cause of the brake squeal on my car would apply regardless of whether the car had performance brakes or not. So make sure if you have an issue, it gets properly investigated. Not saying that my issue applies to everyone, but it does raise the question of how much actual attention are dealers/shops paying to this complaint. It's much easier to dismiss it than properly investigate the problem.

[ResIpsaLoquitur]

Originally Posted by Moonstone_UK

My car has Carbon Ceramics and I've been plagued by brake squeal from the get-go. I wanted to post this up in case it helps others who have been experiencing the same issue and have struggled to find the cause.

It's well-documented that BMW M brakes (whether steels or ceramic) are renowned for making noise. BMW has made videos and your dealer will hand you a leaflet specially made to "educate" you.

My issue has been that the squealing on the brakes happens when I'm not braking. I posted a thread about this earlier this year, but felt a new thread may be more useful for those searching Google for a solution.

I'd read lots of conflicting info on CCBs specifically:

• That you should not apply any lube or ant-squeal paste (BMW)
• That you should actually apply some lube for cars that are 48 months old, or older (BMW Parts Catalogue)
• That you need bed the brakes properly (various youtube videos)
• That you don't need to bed the brakes at all and should drive gently for the first 600 miles on a new car, or one that has just had new pads or discs fitted (BMW)
• That you should apply Porsche anti-rattle shims (this forum)
• That you should drive the car hard regularly.

I've tried all of the above on the front brakes as well as changing the pads. Nothing cured the problem. In fact trying to re-bed the brakes actually would make the problem worse. Rather than be an issue when the brakes were cold, mine would get worse as they heated up.

The squeal would disappear and return at random for varying periods of time regardless of all of the above. BMW said that everything looks normal and pointed me to the same well-worn "functional brake noise" argument. I really don't mind functional brake noise. I generally enjoy the car for what it is and so regularly drive it hard, so "functional brake noise" isn't an issue.

On Friday after finally getting round to getting a tool to disengage the electronic parking brake, I decided to have a look at the rears. Now, I'd pretty much dismissed these as being the issue, given that the general consensus is that they don't really do much compared to the fronts and that as I'd experienced constant squealing when turning right at low speeds that it must be related to the fronts as those wheels actually steer.

However, having completely ruled out everything else, I thought, as a last resort, I should rule these out too.

On examination the brake pad material has plenty of life left in them, around 15mm. But the backing plates were a different story. All of them were pretty rusty and corroded. In particular the right-hand, rear-inner pad was solid and I had to use a hammer and a screw driver to release it from the calliper.

I also found a fair bit of muck in and around pistons as well as the textile material on the back of inner pads being pretty chewed up. The lugs that locate into the silver shims on the caliper were particularly corroded.

I got rid of all the corrosion by using a wire brush and applied anti-squeal to the pads and since then, on multiple trips my car has been silent, on the brakes and off.

So the moral of the story here, is that if you're suffering from badly squeaking CCBs (or M compound brakes) don't assume that your issue is down to "functional brake noise". Although the (CCB) pads may last forever, the metal backing plates will still corrode over that time and it's well worth looking at these, especially on the rears, due to it being a floating calliper. If the pad isn't retracting properly when things heat up and expand, that could be the squeal that you're chasing.

The constant loud squeal at in-town speeds had gotten to the stage that it was starting to ruin the car for me and everybody was telling me I just had to put up with it. Dealers seem to have gotten to the point where they just roll their eyes and say "it's normal" without fully investigating the issue, but in my case CCBs have been a red-herring. The cause of the brake squeal on my car would apply regardless of whether the car had performance brakes or not. So make sure if you have an issue, it gets properly investigated. Not saying that my issue applies to everyone, but it does raise the question of how much actual attention are dealers/shops paying to this complaint. It's much easier to dismiss it than properly investigate the problem.

Excellent write up! Thank you taking the time to share with us!

[Maverik259]

im curious though why you were plagued by this from day 1 with corrosion if that was the cause....

[Evil Derboy]

Originally Posted by Maverik259

im curious though why you were plagued by this from day 1 with corrosion if that was the cause....

“Day 1” equals day 1 of my ownership. I bought my car used. It was 3 years old and still on the original pads.

[shawnhayes]

Yeah, I've heard so so much about the brake squeal. I've never had it. But, my car is garaged and tracked. I didn't have it on my 2018 with metal, nor on my CS with CCB. Wonder if it's corrosion on all of them.

Shawn

[STi from DSM]

This is fantastic to hear and the EXACT symptoms I have with my 2018. I did notice that during rainy weather it went away completely, and now that it was dry again for two days it is back again. I have the steel brakes. I would say 50% of the time with light braking it will make the noise and it can be REALLY loud at times.

[josec70]

Originally Posted by STi from DSM

This is fantastic to hear and the EXACT symptoms I have with my 2018. I did notice that during rainy weather it went away completely, and now that it was dry again for two days it is back again. I have the steel brakes. I would say 50% of the time with light braking it will make the noise and it can be REALLY loud at times.

Try EBC Red-stuff Pads if the noise persists. I put these on my last M5 (19'M5C) and they were very quiet, had less dust and felt very OEM in terms of feel. My brother now owns that car and the brakes are still super quiet.