Racing Brake Carbon Ceramic & Lightweight Iron Rotor Group Buy

[JAJ]

Resins are what hold all carbon composites together and are a key component to the strength and stiffness of composites. That's why when a carbon fiber race car burns down, all that's left is the carbon fibers themselves that is as flimsy as it was before the resins were added at the beginning of manufacturing. There's a big difference from saying the "Carbon" is what burns off vs the "Resin". That's a fundamental understanding of composites. You also need to acknowledge the resin and loss of mass from the center of the rotor due to heat. It's not just the surface.

Back in the 1980's I was chief engineer of a company that made some pretty sophisticated electronic equipment that was big, heavy and produced a lot of heat when it was in operation. We used a lot of different plastics in the manufacturing, so I'm pretty familiar with resins and how they work. Part of my job was to figure out which ones to use and how to use them - reinforce them, leave them alone, hot or cold cure, all that stuff. To get regulatory approval we had to test some items to destruction, in the sense that we had to prove it wouldn't burn under the most extreme conditions it could encounter. Resins and reinforced plastics are not a mystery.

The thing with carbon ceramic brake rotors is that, according to Brembo SGL and Surface Transforms, the manufacturing process turns "the resin" into pure carbon. If you dig around the internet a bit, you'll find an industrial process called "Polymer-to-Carbon Conversion" which converts a polymer resin into a form of carbon called "glassy carbon" with characteristics similar to the carbon crystals described below in the Surface Transforms quote.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213281/

The Brembo SGL website describes their manufacturing process as "The production process of the ceramic brake body requires a preform pressed with binding resin to a so called green body which will be converted in the ceramic component by first carbonizing at 900 °C and second by liquid silicon infiltration (siliconization) at 1700 °C in vacuum atmosphere."

The Surface Transforms website describes carbonizing as "...the pre-forms are heated, they begin to lose their non-carbon atoms, plus a few carbon atoms, in the form of various gases including water vapor, ammonia, carbon monoxide, carbon dioxide, hydrogen, nitrogen, and others. As the non-carbon atoms are expelled, the remaining carbon atoms form tightly bonded carbon crystals"

Because carbonizing drives off a lot of the original chemicals that made up the resin, it leaves the ceramic body porous, like a really hard sponge, with microscopic spaces throughout the material. ST fills these spaces with silicon carbide while SGL uses liquid silicon (not silicone, the plastic, but elemental silicon, the stuff that computer chips and glass are made from).

That's why carbon ceramic rotors are hard to make, but it's also why they perform the way they do. By the end of the manufacturing cycle, they're made of carbon fiber, carbon crystals, silicon and silicon carbide. There are three different forms of carbon in the product. From the standpoint of weight loss from high temperature use, the silicon carbide and silicon are immune - they don't break down or vaporize until they're in the thousands of degrees.

That leaves the carbon fiber and the carbon crystals as candidates to explain why rotors get lighter as they get used up. SGL says "we use carbon fibers which are given a special protective coating", so for a Brembo SGL rotor, the only things left that can oxidize are the carbon crystals that are spread throughout the ceramic structure. If you get the rotor hot enough, the carbon oxidizes and departs in the form of carbon dioxide, leaving voids in the structure (it becomes a sponge again) making the rotor lighter. "Hot enough" seems to be around 700 to 900 degrees C, depending who made the rotor.

And of course, if the rotor gets hot enough all the way through, it will lose mass all the way through, not just on the surface.

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[BillyJRacing]

I stand corrected in regards to the resin - carbon burning off comments. Thank you for the insight and correction.

 

[Epiphany]

Because carbonizing drives off a lot of the original chemicals that made up the resin, it leaves the ceramic body porous, like a really hard sponge, with microscopic spaces throughout the material. ST fills these spaces with silicon carbide while SGL uses liquid silicon (not silicone, the plastic, but elemental silicon, the stuff that computer chips and glass are made from).

JAJ, before carbonizing, what do you think a general percentage number would be for how much of the rotor composition would have been resin?

 

[JAJ]

I stand corrected in regards to the resin - carbon burning off comments. Thank you for the insight and correction.

Hey, I really appreciate your input on this forum - you're great to have around! I really didn't want to write that post, but I was concerned that some of the folks reading the thread might get the idea that a carbon ceramic brake rotor was made the same way as a carbon fiber panel or wheel.

While carbon fiber structures are amazing enough, the carbon ceramic rotor is a whole different level of technology and intellectual endeavor. That they can be made at all is a technical triumph. Think about it - they start with a bunch of powders and end up with something super strong, nearly as hard as diamond that can withstand temperatures high enough to melt iron (not for long, but they can do it and they won't burst into flame). And they can make it at a price that actually works for consumers. It's amazing.

 

[JAJ]

JAJ, before carbonizing, what do you think a general percentage number would be for how much of the rotor composition would have been resin?

The concentration of resin in the mix would be dictated by two factors - first, how wet does the mix need to be (the best comparison is clay before it's molded into a ceramic product - it could be stiff or runny) and second, how much void space do you need in the green body for the filler that comes later. There's just no way to guess - it's a trade secret and it'll be well-guarded.

 

[Epiphany]

In researching much of this I noticed something interesting from Brembo.

I spoke with Ford brake engineers a few years ago regarding their choice of SHW instead of Brembo on the GT350. It would have made sense that with a Brembo caliper that we would have seen a Brembo rotor. For reasons I was asked not to share, it didn't work out that way. So we ended up with SHW rotors instead on the GT350 as well as on the GT500. Now it looks like Brembo is going to offer something similar, albeit without having to use pins radially ala SHW or in the more conventional manner we see when hats/rotors are bolted together in single shear. A Brembo release from three months or so ago shows they have developed what they are calling a "dual-cast floating brake disc."

Aluminum hat, iron ring, interesting execution in comparison to what SHW is doing.

https://www.brembo.com/en/company/news/dual-cast-brake-disc

 

[JAJ]

In researching much of this I noticed something interesting from Brembo.

I spoke with Ford brake engineers a few years ago regarding their choice of SHW instead of Brembo on the GT350. It would have made sense that with a Brembo caliper that we would have seen a Brembo rotor. For reasons I was asked not to share, it didn't work out that way. So we ended up with SHW rotors instead on the GT350 as well as on the GT500. Now it looks like Brembo is going to offer something similar, albeit without having to use pins radially ala SHW or in the more conventional manner we see when hats/rotors are bolted together in single shear. A Brembo release from three months or so ago shows they have developed what they are calling a "dual-cast floating brake disc."

Aluminum hat, iron ring, interesting execution in comparison to what SHW is doing.

https://www.brembo.com/en/company/news/dual-cast-brake-disc

Looks like SHW's patent ran out.

Found this video on testing Brembo Formula 1 carbon-carbon brakes:

 

[50 Deep]

Wanted to give a thanks to everyone that participated in the group buy now that it is officially closed. We will have 4 complete GT500 setups being sent out to owners soon. The street compound pads are also finishing up production as they had to be newly designed for the GT500. It appears the rear pad setup here is unlike anything else from Brembo. RB will also be designing their own caliper setup in the future.

I have 4330 miles on the car now, which puts me at roughly 575 street miles with the brakes. Currently with the street compound pads up front and OEM pads in the rear. Thus far the setup has no braking noise and virtually no brake dust on the wheels. It has been pretty interesting to feel how much more effective the brakes get with some heat. I did the initial bedding late one evening, and was surprised at how grabby the brakes were once out driving the next day when it was 90+ degrees out. Braking is great when cold, but you can really tell the difference when the car is sending you into the steering wheel.

Although the OEM rear pads are ok for street use, I am looking forward to having the matching compound for the rear and get the full effect. Very pleased with the initial bite, modulation, braking feel, and of course the weight reduction.

I will report back with more data/photos in a separate thread once we have everything installed and can get some more street/track time.

Cheers!

 

[Tomster]

Not sure I wanna do that without knowing where the rotors came from. Daytona isn't a place to run unproven stuff. Especially brakes & tires.

Unless RB repurposes CCB & CCM rotors from other applications (likely -nothing wrong with that), the inconsistency of the usage of CCB and CCM is concerning because they are different technologies that perform differently.

A big thing that post is missing is Thermal Capacity -which is the reason Carbon Ceramic brakes are larger than iron brakes in the same application. Let's look at some examples:

991 GT3 Iron: 380 mm & 380 mm
991 GT3 PCCB: 410 mm & 390 mm - 8% & 3% larger

MP4 12C Iron: 370 mm & 350 mm
MP4 12C CC: 394 mm & 380 mm - 7% & 9% larger

AMG GT-S Iron: 390 mm & 360 mm
AMG GT-S CC: 401 mm & 360 mm - 3% & same

F430 Iron: 330 mm
F430 CCM: 380 mm & 350 mm - 15% & 6% larger

612 Iron: 345 mm & 330 mm
612 CC: 380 mm & 350 mm - 10% & 6% larger

458 & 488 GTB: 398 mm / 360 mm


SO, if the GT500's 16.5" (420 mm) iron rotor had a similar 7% increase in diameter, that would = 448 mm or 17.65" rotor

But let's go with the AMG GT's 3% increase. That would still = 433 mm, or a 17" rotor.

Neither of these are really possible without going to 21-22" wheels.

The GT500's 16.5" rotors are already some of the biggest out there and can stop the car lap after lap on end with stock street brake pads. That was the goal for the project and it was definitely accomplished.

It's quite documented and well known that people who track their cars remove CC rotors and replace them with iron. Not only is it less expensive, but the iron rotors have more thermal capacity and can use far more aggressive pad compounds:

https://www.essexparts.com/essex-de...ook-disc-pair-front-398x36mm-mercedes-amg-gts

I'm actually in favor of CC brakes. They're lighter for unsprung weight, improve steering feel and handling. They are also far better for street use than iron from a cost perspective. However for track-focused cars, they are NOT cost effective and you'll be paying a premium for the reduced weight. But i'm all for it. Many are not. However, carbon wheels do far more than carbon brakes in this department:

https://motoiq.com/tested-carbon-revolution-carbon-fiber-wheels/

I'm always trying to help the community and enthusiasts. I spend more time on here and FB than I should trying to help people. Mostly to answer misconceptions and let them know they don't need to spend money on what they're trying to accomplish; and they should put that money towards more track days and just have fun. Many try to push an unnecessary 'need' to generate a sale (not claiming that you are, because I don't recall you claiming these will solve a braking deficiency).

However, it's not up to ME to determine if these brakes are good on my own dollar. It'll cost at least $10K in 4-5 sets of tires alone, not including fuel, track rental, track insurance, etc... to do a proper brake test. I don't see a reason to spend that kind of money to test someone else's product for them to have more credibility.


An arrangement could be made for me to test 3rd party products. Cost is always a concern and carbon wheels deliver more performance than carbon brakes. As mentioned before, using the same size carbon brakes as iron will result in lower thermal capacity on track.

It's a shame people park their carbon wheels. It's an amazing technology that really transforms the car's handling and feel. Going to aluminum hurts all of those aspects and makes the car slower on track. It would be very ironic for someone to ditch carbon wheels and use carbon brakes on track.

Those companies aren't making carbon ceramic brakes. If someone was putting a set of Wilwood brakes on their GT500 for road course use, I would probably also express similar concerns, as I have done with people putting smaller AP calipers on their GT350s.

I'm not sure i'd claim they are 'established' Carbon Ceramic manufacturers, but rather have made kits adapting existing rotors for new applications.

For the GT350 or most cars, using an OEM Brembo CC rotor isn't a huge risk and would probably be fine for 99.5% of the owner who track them. However, upon learning about a "new/custom" unproven rotor, there is a risk since Carbon Ceramic rotors are not simple devices. Neither are carbon wheels.

Putting a CC on a GT500 is also a risk, and then using an unproven "new" CC rotor on a GT500 increases that risk even further. -All to solve a problem that doesn't exist. I get the need for wanting to make the car lighter, and I've already stated for street use and for most people on track, it MIGHT/probably will be fine. But those are legitimate concerns.

I was reviewing the thread again after recent discussion about the RB CCB and Billy's input pertaining to the RB brakes.

Is there a CCB brake that has gone through the QC process and testing that would be suitable for our 500's?

 

[Tonymustang302]

I just dont understand the necessity for this.

ALL the GT3 and cup3 porsches at my track switch to iron rotors from their CF ones.

the people that built my 350 have worked with P1 down to gt4 and said iron is the way to go for track use.

 

[raiderjatt02]

I just dont understand the necessity for this.

ALL the GT3 and cup3 porsches at my track switch to iron rotors from their CF ones.

the people that built my 350 have worked with P1 down to gt4 and said iron is the way to go for track use.

The unsprung weight advantage is huge on track. Necessary? Not at all. Especially at the current prices. They're expensive as fuck. Iron is the way to go as far as costs are concerned which is why a lot of people that track often switch to iron.

For the street, CCB are nice because they last forever since they don't experience the heat and abuse of track work. They look nice. The lighter weight makes the car feel more lively and handle better. The biggest advantage on the street though is the virtual elimination of brake dust. It'll keep those wheels shiny for a hell of a lot longer.

Are those advantages worth the price? Up to you to decide. I'd love to make the switch when the tech gets cheaper but personally, it isn't worth it to me. Everyone's needs are different but those are the main points to consider.

 

[Dharri21]

How has the CCB pricing done in the last year. I would love to switch over just for street and spirited driving use. It would be nice to see a non track ccb system priced less.

 

[Tonymustang302]

The unsprung weight advantage is huge on track. Necessary? Not at all. Especially at the current prices. They're expensive as fuck. Iron is the way to go as far as costs are concerned which is why a lot of people that track often switch to iron.

For the street, CCB are nice because they last forever since they don't experience the heat and abuse of track work. They look nice. The lighter weight makes the car feel more lively and handle better. The biggest advantage on the street though is the virtual elimination of brake dust. It'll keep those wheels shiny for a hell of a lot longer.

Are those advantages worth the price? Up to you to decide. I'd love to make the switch when the tech gets cheaper but personally, it isn't worth it to me. Everyone's needs are different but those are the main points to consider.

i guess i take the word of race car builders and drivers over hype…..to each is their own.

i have girodiscs front and rear so im good. But appreciate people like T are always looking for the next best thing.

 

[JAJ]

i guess i take the word of race car builders and drivers over hype…..to each is their own.

i have girodiscs front and rear so im good. But appreciate people like T are always looking for the next best thing.

I think in the world of race car builders (I've known a few and helped some trackside), you'll find there is a lot of "I've always done it this way and it's always given me what I want" happening. Predictability is crucial. So when something new comes along, it takes a while for the veterans to adopt it. Then there's the rules - CCM brakes may not be allowed in some classes.

If you want an interesting read on CCM brakes, check this out - they get a major mention:

https://media.stellantisnorthamerica.com/newsrelease.do?id=17086&mid=

If that doesn't convince you that CCM brakes are real, then read this Brembo blog post from 2015:

https://blog.racetechnologies.com/2015/04/02/brembo-ccm-r-carbon-ceramic-for-racing/

There's always a lot of fear-uncertainty-doubt ("FUD") when something new comes along. After enough people have tried the new tech and realized that it works, things evolve. CCM brakes are real, and over the next few years, more people will try them and they'll become more common.

 

[Tomster]

Why RB didn't just bite the bullet and have these tested to OEM standard.

I would have a set tomorrow, but the guy who developed our cars says to steer clear.

he has no dog in the fight and he is not trying to sell me something. I'm going with Billy's advice on this one.

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