CCB or aftermarket Brembo brakes?

[swamp2]

Originally Posted by Boss330

isn't the reason they heat up more because the CSiC rotors can be matched with a much higher friction brake pad? Since the CSiC rotor have much harder surface and therefore less prone to wear they can also have a brake pad that has higher friction. Higher friction causes more heat obviously.

No. Max friction is determined/delivered by the tire. Once can't put more friction into the disc than that available at the traction limit which any OEM brake system will get you to. The primary reason CSiC disc run hotter is because they have significantly less mass. They do make up for the less mass with a higher specific heat but it can't counter the much less mass (in the rotors themselves as opposed to disc assembly or rotor+hat). The result is what we call less thermal mass mass * C (specific heat). Now to have good fade performance at this normally detrimental higher operating temperature the disc is mated with a matched brake pad with a "knee" in its friction vs. temperature curve pushed to the right (higher temperature) compared with a pad for a cast iron disc.

Now of course that being said we are seeing larger diameter and perhaps even thicker CSiC discs. At some point if the weight savings is not pushed so heavily and their specific heat is tweaked upwards by the compounding, they could have a similar or even higher thermal mass as compared to the disc they replace at the OEM level.

[CanAutM3]

Originally Posted by syl2121201

So how many of you guys manage to keep the car longer than the warranty and modify your car, treat your car with your inner passionate instead of a DD tool with some tracking potential? If you are just gonna lease the car and return it then I agree this option is a totally waste of money. However for ppl who's going to modify the car, they gonna need the BBK sooner or later for another 8000, so why not take the chance to get it from stock plus you get the carbon ceramic rotors. Even if the rotors can not maintain long enough you could still get steel rotors for replacement like the after market BBK. Am I making any mistakes from this point of view?

IMO, there is no real need for a BBK, during or after warranty.

Read this post.

[CanAutM3]

Originally Posted by aus

For $8,100... just get the wheels/tires and pocket the rest for more track time.

^ This in my case

[Boss330]

Originally Posted by swamp2

No. Max friction is determined/delivered by the tire. Once can't put more friction into the disc than that available at the traction limit which any OEM brake system will get you to. The primary reason CSiC disc run hotter is because they have significantly less mass. They do make up for the less mass with a higher specific heat but it can't counter the much less mass (in the rotors themselves as opposed to disc assembly or rotor+hat). The result is what we call less thermal mass mass * C (specific heat). Now to have good fade performance at this normally detrimental higher operating temperature the disc is mated with a matched brake pad with a "knee" in its friction vs. temperature curve pushed to the right (higher temperature) compared with a pad for a cast iron disc.

Now of course that being said we are seeing larger diameter and perhaps even thicker CSiC discs. At some point if the weight savings is not pushed so heavily and their specific heat is tweaked upwards by the compounding, they could have a similar or even higher thermal mass as compared to the disc they replace at the OEM level.

Forgot the obvious fact that friction is tire limited (a point BMW also makes in the F10 M5 CSiC manual). Thanks for the clarification

[CanAutM3]

Originally Posted by Boss330

Forgot the obvious fact that friction is tire limited (a point BMW also makes in the F10 M5 CSiC manual). Thanks for the clarification

IIRC from my past readings, the brake torque and tire grip relationship is quite complex. Depending on the brake system's capability, the transition point between dynamic friction and static friction varies at the pad/disc interface. A better brake system can be able to generate more dynamic brake torque with the same tire (until the ultimate limit of the tire is reached that is). With a lesser system, once the heat absorption threshold has been reached, applying more pressure on the pads ends up in lock-up while for the better brake system it can still absorb the heat and maintain dynamic friction. The article mentioned all sorts of material tear and transfers between the disc and pad at the molecular level, too scientific for me to remember .

[bing240sx]

i asked this question before not sure if it has been answered. do we know yet if the E9X BBk's can be swapped from an E90 on to an F80 or will stop tech produce a new bracket to bolt on the E9X trophy kit onto the F8X?

i appreciate all the science here but let's also admit that big brakes are gorgeous. you don't need a business case to make the decision; we're talking about a $80k+ car here that depreciated 50% in 3 years. we're all different degrees of silly.

[Boss330]

Originally Posted by CanAutM3

IIRC for my past readings, the brake torque and tire grip relationship is quite complex. Depending on the brake system's capability, the transition point between dynamic friction and static friction varies at the pad/disc interface. A better brake system will be able to generate more dynamic brake torque with the same tire. With a lesser system, once the heat absorption threshold has been reached, applying more pressure on the pads ends up in lock-up while for the better brake system it can still absorb the heat and maintain dynamic friction. The article mentioned all sorts of material tear and transfers between the disc and pad at the molecular level, too scientific for me to remember .

The F10 M5 CCB manual covers this topic as well and says that CCB can slightly reduce braking distance because of a better initial brake bite and better ability to exploit tire friction (or something along those lines).

[Zoli007]

Originally Posted by bing240sx

i asked this question before not sure if it has been answered. do we know yet if the E9X BBk's can be swapped from an E90 on to an F80 or will stop tech produce a new bracket to bolt on the E9X trophy kit onto the F8X?

i appreciate all the science here but let's also admit that big brakes are gorgeous. you don't need a business case to make the decision; we're talking about a $80k+ car here that depreciated 50% in 3 years. we're all different degrees of silly.

They may physically fit, likely requiring a new bracket. But the thing I'd be worried about is them matching the new cars brake system. There is very little chance the E9x brake system carried the exact same volume of brake fluid in the calipers therefore possibly causing a significant DOWNgrade in braking performance in the F8x.

A BBK should be specifically designed for the car you are going to use it for and not looking simply for a good physical fit.

[Alpine F31]

Originally Posted by bing240sx

i appreciate all the science here but let's also admit that big brakes are gorgeous. you don't need a business case to make the decision; we're talking about a $80k+ car here that depreciated 50% in 3 years. we're all different degrees of silly.

BAM! Cant argue that!

[gee-m-w]

Originally Posted by CanAutM3

IMO, there is no real need for a BBK, during or after warranty.

Read this post.

So you're only getting about 10 days on track or 5 weekends from a set of OEM BMW rotors? That's pretty bad. My pads last longer than that. My rotors last 3-4x as long. I don't see how it's economically viable to track on BMW OEM steel rotors.

[Sedan_Clan]

Originally Posted by gee-m-w

So you're only getting about 10 days on track or 5 weekends from a set of OEM BMW rotors? That's pretty bad. My pads last longer than that. My rotors last 3-4x as long. I don't see how it's economically viable to track on BMW OEM steel rotors.

You drive a significantly slower car (..that's not debatable). It takes less to slow it down. Just jabbin' at 'cha!

[gee-m-w]

Originally Posted by Sedan_Clan

You drive a significantly slower car (..that's not debatable). It takes less to slow it down. Just jabbin' at 'cha!

It's at least 1/2 ton heavier. We established it in another thread. It's like when Audi takes delivery on steel and aluminum it contains some kind of dark matter and a different atomic weight. BMW just knows how to bend it better.

The crack team on this board is so obsessed with rotor diameter that they neglected to investigate rotor thickness, a key component in rotor longevity. Another great reason the CCB will last 10x as long as a BMW steel rotor, which we have now determined to be about as strong as Reynolds wrap.

[Alpine F31]

Originally Posted by aus

For $8,100, I'd rather have a Brembo 380mm kit
.

You probably already know this. The CCB on the M3/M4 are made by Brembo.

I found a great article specific to this subject that you all should read. The bottom line was this:

Weighing the benefits and drawbacks of carbon ceramic brakes, it’s clear that they are ideal only for those who really need them – or for those who like spending money to make a fashion statement.

For anyone thinking of frequently or even occasionally taking their car to the track, a carbon ceramic braking system is a wise choice for better lap times and even more fun. There are some (very small) advantages for the road-only drivers, like the longer life of the brakes, but for many thousands of dollars it’s not worth the added cost.

Personally, I want them just because they look so fuckin awesome. No one needs them as we all agree the stock brakes are great. But I'll be damned if I don't lust for them.

[CanAutM3]

Originally Posted by gee-m-w

So you're only getting about 10 days on track or 5 weekends from a set of OEM BMW rotors? That's pretty bad. My pads last longer than that. My rotors last 3-4x as long. I don't see how it's economically viable to track on BMW OEM steel rotors.

Do you even know how to read and do math ?

[gee-m-w]

Brakes is not generally something I go cheap on or try to save money on. It's safety equipment. It's the one thing that lets me bring the car home not broken when I go out on a road course.

Note: this is for the M5/M6

[Sedan_Clan]

Originally Posted by gee-m-w

Brakes is not generally something I go cheap on or try to save money on. It's safety equipment. It's the one thing that lets me bring the car home not broken when I go out on a road course.

So you're asserting that anybody who doesn't opt for CCB's is "going cheap" when the OEM brakes are capable and have been tested thoroughly?

[CanAutM3]

Originally Posted by gee-m-w

BMW steel rotor, which we have now determined to be about as strong as Reynolds wrap.

My experience:

2 sets of front rotors for 5 season at 18-20 days per season that is 45+ days for the fronts
1 set of rears for 5½ seasons at 18-20 days per season that is 95+ days for the rears

Not too bad IMO

[gee-m-w]

Originally Posted by CanAutM3

My experience:

2 sets of front rotors for 5 season at 18-20 days per season that is 45+ days for the fronts
1 set of rears for 5½ seasons at 18-20 days per season that is 95+ days for the rears

Not too bad IMO

Sorry it was confusing the way you wrote it the first time, and a bit confusing this time too. So your rears lasted 5 years? Or you had to replace them once in 5 years and they lasted 2.5 years? Likewise with the fronts, was it 2 replacements and 3 sets total?

[Boss330]

Originally Posted by gee-m-w

So you're only getting about 10 days on track or 5 weekends from a set of OEM BMW rotors? That's pretty bad. My pads last longer than that. My rotors last 3-4x as long. I don't see how it's economically viable to track on BMW OEM steel rotors.

Originally Posted by CanAutM3

Do you even know how to read and do math ?

gee-m-w: In the post he clearly states that he:

• Does 18-20 trackdays per season
• Has done 5 1/2 season
• Has changed rotors twice

To me, that equates to between 99 - 110 track days the last 5 1/2 years

Meaning that one set of rotors at least is good for around 45+ trackdays (from his post I gather that his current front rotors aren't done yet so they should last a few trackdays longer, bringing the average up).

How did you get 10 trackdays out of that post, even though you were confused about 2 or 3 sets. It's NOWHERE near 10 either way

[CanAutM3]

Originally Posted by gee-m-w

Sorry it was confusing the way you wrote it the first time, and a bit confusing this time too. So your rears lasted 5 years? Or you had to replace them once in 5 years and they lasted 2.5 years? Likewise with the fronts, was it 2 replacements and 3 sets total?

I replaced my fronts twice, the second time mid season this summer. So I used two sets over 5 years (the ones on the car only have half a season on them and are still in perfect shape).

The rears need to be replaced in the spring before the track season starts. They are still good enough for winter DD but no longer suitable for track use. They are still the original discs, so they will have lasted 5½ track seasons and almost 6 years.

[swamp2]

Originally Posted by CanAutM3

IIRC for my past readings, the brake torque and tire grip relationship is quite complex. Depending on the brake system's capability, the transition point between dynamic friction and static friction varies at the pad/disc interface. A better brake system can be able to generate more dynamic brake torque with the same tire (until the ultimate limit of the tire is reached that is). With a lesser system, once the heat absorption threshold has been reached, applying more pressure on the pads ends up in lock-up while for the better brake system it can still absorb the heat and maintain dynamic friction. The article mentioned all sorts of material tear and transfers between the disc and pad at the molecular level, too scientific for me to remember .

I'd like to see that article.

It is certainly understood that grip force varies with slip and is maximized with some level of slip (not under lockup and not under light braking). That being said I would find it quite surprising if the tire-road contact patch can or does have any "awareness" of the pad-rotor contact. Specifically let's consider the absense of fade conditions. With either type of brake system it is always possible to obtain all braking conditions, light/rolling, lockup and ideal (i.e. some very limited lockup - slip).

Now if we want to dive into a great amount of detail during the actual achievement of slip under ideal braking, there may be some element of the thermal performance of a CSiC that provide some slightly improved dynamic modulation capability but that too is going to be limited by the ABS software more so than by the operator.

Any effect here is thus extremely minimal and more academic if it even exists.

[swamp2]

Originally Posted by Boss330

The F10 M5 CCB manual covers this topic as well and says that CCB can slightly reduce braking distance because of a better initial brake bite and better ability to exploit tire friction (or something along those lines).

I'd like to see scientific and statistical data that support this ///Marketing point of view!