[ChiefM]

Originally Posted by ledphut

Seeing as you don’t yet have a BMW in your possession yet, you would’ve saved yourself some time typing out all those paragraphs by doing a bit of research on the 2018-current M-Sport brakes.

The problem doesn’t have to do with any of the things you mentioned. It’s a well documented issue that most likely has to do with the brake pad compound BMW used. Similar to brand new carbon ceramics on certain hypercars; they squeak constantly. It seeems that it has more to do with the hardness quotient of the pads/rotors. People have simply replaced the pads and the squeaking stops.

Brake system operation and physics don’t change bro. I do work on the side on late model bmws on the regular. Yes late model bmw with m sport brakes squeal, and everyone I have looked at has one of the above issues. Do you know why the squealing stops when you replace the pads? The front pads have an adhesive back. Do me a favor and don’t talk down to me or others, it’s very rude😉

[NavyBlue]

Thanks for all the replies above.
Anyways, I've got 4 months left on orig factory warranty.
It was the Service Advisor at local BMW dealer that told me that the squealing brakes on M cars are normal. So guess I'm going back to another BMW dealer's service dept to have a real Technician look & inspect the brakes to at least to see if there's a rock or debris or adhesive wearing out, or whatever...

[mjr24]

Originally Posted by ChiefM

Brake system operation and physics don’t change bro. I do work on the side on late model bmws on the regular. Yes late model bmw with m sport brakes squeal, and everyone I have looked at has one of the above issues. Do you know why the squealing stops when you replace the pads? The front pads have an adhesive back. Do me a favor and don’t talk down to me or others, it’s very rude��

Your explanation doesn't fly regardless of what you do on the side. All my M's have squeaked......and I am talking 200k miles worth of driving. I've never even HAD TO CHANGE THE BRAKE PADS ONCE IN ANY OF MY M CARS. In other words, don't give me this the calipers are bad speech. You have absolutely zero idea what you are talking about. Ledphut's explanation is likely what the issue is.....and this is the same on Porsche, AMG, M, etc.....they ALL squeak. I don't even get mad about it anymore because it's never not been the case (brakes squealing) in 16 years of owning M cars now.

[Salottox5m]

My m5 had same issue - very common in high performance brakes - they need to warm up - few hard stops should do it

My buddy had Ferrari f430 - same exact thing & squaked until warm

Squeaking brakes and high performance cars go hand in hand

Warm up brakes & I think you ll be fine after.

[dubbrand]

I have the isweep pads and my brakes still squeek from time to time randomly. Haven't noticed any specific conditions that make them do it. It just happens, but definitely less than the oem pads.

[Tenac]

When I keep my brakes clean they don't make any noise, but after a hard day of canyon driving and a week of DD they tend to make noise until I clean them again.

[ChiefM]

Originally Posted by mjr24

Your explanation doesn't fly regardless of what you do on the side. All my M's have squeaked......and I am talking 200k miles worth of driving. I've never even HAD TO CHANGE THE BRAKE PADS ONCE IN ANY OF MY M CARS. In other words, don't give me this the calipers are bad speech. You have absolutely zero idea what you are talking about. Ledphut's explanation is likely what the issue is.....and this is the same on Porsche, AMG, M, etc.....they ALL squeak. I don't even get mad about it anymore because it's never not been the case (brakes squealing) in 16 years of owning M cars now.

Dude, I know exactly what I am talking about. I am a master mechanic with 20 years of experience. I was simply giving friendly advice based on that. I am not going to argue with keyboard warriors.
Anyways, attached is from BMW TSB regarding troubleshooting low speed brake squeal.
Lastly, if my M850i M sport brakes squeal I will document and post everything I do to figure the issue out and what I do to solve it.

[aosman]

Originally Posted by Tenac

When I keep my brakes clean they don't make any noise, but after a hard day of canyon driving and a week of DD they tend to make noise until I clean them again.

Interesting! How do you clean your brakes to get rid of the noise? I'd be curious to try that myself.

[aosman]

Originally Posted by ChiefM

Master mechanic here. Still waiting on my 24 M850i to delivered. Have been a Porsche guy and Mercedes guy since my early 30s, before then was a poor Honda and Acura kid. Needless to say, I do all my own work. 2020 with 3500 miles? Ok let me brake this down.
The squealing you hear is one of 3 things. Foreign object (think small rock) between brake pad and rotor, the brake pad vibrating at high frequency, or a wear indicator. Let me explain the last two. When brake pads are installed all guide pins in floating calipers are lubricated, and anti squeal compound is applied to the back of the brake pads. The anti squeal is essentially a light glue, some manufacturers use shims and a soft backing on brake pads to prevent the use of anti squeal. These statements apply to the rear brakes of the 8 series. The front brakes are fixed 4 piston calipers. The brake pads come with adhesive on the back. This adhesive is effectively the anti squeal. Your car is 4 years old. Regardless of mileage, dirt, grime, salt all work their way in and unstick the pads. I am not saying the bmw tech is right, it’s not normal, but if these are original pads, hate to say it but yeah this is to be expected.
Another possibility is that the 8 series doesn’t have brake wear sensors on all 4 corners. This is a common cost cutting measure these days, even in high end cars. What this means is a brake pad is squealing because it’s about to ruin a rotor, on a wheel without a brake pad sensor.
Anyways, from a blue collar guy who ended up being more successful than he ever thought he would be, this is my advice to you.
Go to harbor freight, get a jack and some jack stands. Make friends with a mechanic and inspect your front and rear pads inboard and outboard pad on each wheel. If thickness is good on all four corners, feel your rotors from the inside of the machined face to the outside. It should feel smooth with no lip on the outside edge. If you grooves or waves, this points to a foreign object embedded in your brake pad. If all looks good, remove your rear calipers and grease the pins and apply anti squeal compound to the back of your brake pads. If you still have a squeal, replace your front brake pads as you can not apply anti squeal to them.
Hope this helps.
Chris

Hey Chris,

Thanks so much for this detailed explanation! It's by far the most comprehensive response I've gotten about the brake squealing.

Your breakdown of the different causes, especially the explanation of anti-squeal on the front vs. rear brakes, makes perfect sense. I really appreciate you taking the time to write all this out.

The mechanic says my front brakes are causing the squeak, but they still have 6mm of pad left. I'll wait to replace them until they're more worn and consider using non-OEM brakes then.

Thanks again, Chris! Appreciate your insights!

[Tenac]

Originally Posted by aosman

Interesting! How do you clean your brakes to get rid of the noise? I'd be curious to try that myself.

Use an iron remove or brake buster spray before you hose it all down. You can also angle the pressure washer to spray on into the calibers and not just on the face of it.. You will see much more come out. I use this stuff here works every time. I've owned so many M's now it's hard to count and they all squeal when dirty but once I get a good wash they all go silent again.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[ChiefM]

Originally Posted by aosman

Hey Chris,

Thanks so much for this detailed explanation! It's by far the most comprehensive response I've gotten about the brake squealing.

Your breakdown of the different causes, especially the explanation of anti-squeal on the front vs. rear brakes, makes perfect sense. I really appreciate you taking the time to write all this out.

The mechanic says my front brakes are causing the squeak, but they still have 6mm of pad left. I'll wait to replace them until they're more worn and consider using non-OEM brakes then.

Thanks again, Chris! Appreciate your insights!

No problem! My pleasure!

[aosman]

Originally Posted by Tenac

Use an iron remove or brake buster spray before you hose it all down. You can also angle the pressure washer to spray on into the calibers and not just on the face of it.. You will see much more come out. I use this stuff here works every time. I've owned so many M's now it's hard to count and they all squeal when dirty but once I get a good wash they all go silent again.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Good stuff! Might give that a shot. Thanks!