CCB Damage?

[Vader97]

I got an M4 with CCBs, heard the brakes squeaking a few days ago so I knew I needed pads. Wasn't able to drive my daily driver and had to use the M4 for the next few days (3-4 days) The sound got more discomforting as it was metal to metal at that point so I drove it slower than usual. Just took it to the dealer and on an inspection video they suggested the front pad AND rotor be replaced. They're not forcing me to do it but could my front rotors really be THAT damaged after an extra 3-4 days of driving with low front pads?

Attached is a pic of the right front rotor with a tiny chip.

[MJ6]

How many miles on the M4?

In all honesty, CCB's aren't going to be as quiet as iron rotors and are known to squeak a good deal. The trade off is that they last much longer (100k + in most cases) and brake dust is non-existent.

If you're not anywhere close to capping that kind of mileage, they're just trying to hustle you into an unnecessary 10k brake job.

[Vader97]

Originally Posted by MJ6

How many miles on the M4?

In all honesty, CCB's aren't going to be as quiet as iron rotors and are known to squeak a good deal. The trade off is that they last much longer (100k + in most cases) and brake dust is non-existent.

If you're not anywhere close to capping that kind of mileage, they're just trying to hustle you into an unnecessary 10k brake job.

That's what I'm saying. Just broke 50k miles on the car. Rotors don't have large thermal cracks and wear marks still look relatively fine (not splotchy). Read that the rotors should last significantly longer than iron ones

[MJ6]

Originally Posted by Vader97

That's what I'm saying. Just broke 50k miles on the car. Rotors don't have large thermal cracks and wear marks still look relatively fine (not splotchy). Read that the rotors should last significantly longer than iron ones

If feasible, I'd see if you can take it to another independent shop for a second opinion.

With only 50k under its belt, they're maybe half way through their life span. Do you know if the car was tracked previously? Because unless there's something physical wrong with the rotors or pads it seems like they're trying to take you for a ride.

[Wanted_M]

The chip doesn't look that bad but what's the dealer basing the replacement criteria on?

Max. permissible width/depth = 2 mm
Max. permissible length = 10 mm

Read below documents for the CCB criteria for replacement so you can make a better decision.
file:///C:/Users/rafaels/Downloads/C...%201%20(6).pdf
file:///C:/Users/rafaels/Downloads/C...%202%20(7).pdf

[Reedomn]

that's why they call it a "stealership"...........

[nickl630]

Couple of things here...

- you mentioned you heard squeaking so you "knew it was time to replace them".. CCB's make excessive noise all the time and its not an indication of pads wearing out/replacement.

- Did the dealer give a pad thickness to you when suggesting replacement? ex: 3/32nd's

- what do the wear indicators look like on the rotors? At 50k miles the pads indeed might need to be replaced.. the rotors should be okay unless the car was pushed/tracked hard in its life.

- if the rotor is indeed still okay and has lots of life left in it.. that small chip wouldn't bother me... but thats me.

[Vader97]

Originally Posted by Wanted_M

The chip doesn't look that bad but what's the dealer basing the replacement criteria on?

Max. permissible width/depth = 2 mm
Max. permissible length = 10 mm

Read below documents for the CCB criteria for replacement so you can make a better decision.
file:///C:/Users/rafaels/Downloads/CCB%20%20Assessing%20the%20CB.pdf%20%C2%B7%20versi on%201%20(6).pdf
file:///C:/Users/rafaels/Downloads/CCB%20Assessing%20the%20CB.pdf%20%C2%B7%20version% 202%20(7).pdf

They didn't even mention a size they just said it should be replaced lmao

[AustinGelbM4]

Originally Posted by Vader97

They didn't even mention a size they just said it should be replaced lmao

Well, the PRIMARY measure of CCB "wear" is weight. Unlike iron rotors which have min thickness stamped on them, CCBs will have a minimum weight printed. Your CCBs should have a lot of life left in them at 50,000 miles unless car was tracked. The "chip" exposes a "flaw" with CCB rotors. Although they are slow wearing and work well with high temps they're really fragile when as it relates to impact. The damage on yours is likely caused by banging/tapping it while mounting and dismounting of the wheel, a common problem which on iron rotors would not have even been an issue. If you're replacing the pads with CCBs good practice usually means changing the rotors too. Yup, they're an expensive option even after initial purchase. The below link is a good read on M Carbon Ceramic Brakes........near the end of the read.

https://www.bmwblog.com/2014/04/13/n...-brake-system/

[horsepower_and_hounds]

Just a suggestion...take good pics of the wear indicators on each rotor indicating the diamond hard coating. if they are still evident and clear then your coating is not worn enough to replace. Pads only....

They will make noise at odd times...... just nature of the beast