Ceramic Composite Brakes
You don't have to be a fan of Formula 1 to appreciate its technological marvels. Today's production cars are loaded with formerly cutting-edge engineering thanks to its high-risk, high-dollar racing programs. Among the latest F1 technology to make it into the hands of mere mortals are ceramic composite brakes, or CCBs (sometimes referred to as carbon-ceramic brakes).
Aston Martin, Audi, Bentley, Bugatti, Ferrari, Lamborghini, Mercedes-Benz and Porsche are among those currently offering CCB. The 2009 Corvette ZR1 will be equipped with CCB, and there's talk that the 2010 Nissan GT-R V Spec will go the same route.
Porsche was the first to make CCB available (which it calls PCCB) on a production car, as optional equipment on the 2001 911 GT2. And the 2008 Boxster S, with its base list price of $55,700, is the most affordable path to CCB currently on the market — although the PCCB option will run you an additional $8,150. That's right: In the brave new world of CCB, "entry level" is north of $60 grand.
Considering the hefty price of admission to the CCB club, the question is: Do ceramic composite brakes live up to the hype?
Putting in All the Stops
In order to answer that question, it's helpful to understand a little bit about the technology behind CCB, which has its roots in F1's "carbon-carbon" brakes (so-called because one type of carbon is thermally bonded with another). The process used to produce the discs for CCB is complex and time-consuming — and therefore costly.
First, carbon fibers are blended with a resin containing carbon and silicon. The compound is then pressed into a mold to create the basic disc shape, including its internal cooling vents. Next, using carefully controlled heat (up to 3,000 degrees Fahrenheit), the resin in the disc is converted to silicon carbide, a material nearly as hard as diamond. This is the "ceramic" in "carbon ceramic." Finally, the center section of the brake rotor — typically made of stainless steel or aluminum — is pinned or bolted to the ceramic composite disc.
Specially formulated brake pads are used in combination with the ceramic composite discs. This is an important point: Whether we're talking about CCB or "conventional" brakes, the pads and the rotors work together to do the braking. More on pad materials later.
CCB: Worth the Weight?
The benefits of CCB begin with the fact that they're lightweight — the discs being approximately 50 percent lighter than those made of cast iron. In the case of the Boxster S, checking the PCCB option drops the overall vehicle weight by 34.4 pounds. But your overstuffed computer bag weighs about that much — so what's the big deal?
Well, when it comes to vehicle dynamics, not all weight is created equal. The brakes — like the wheels and tires, the spindles and approximately half the weight of the suspension components — are unsprung weight, the portion of the vehicle's weight that isn't supported by its suspension.
Reducing a vehicle's unsprung weight allows for better overall control as well as improved ride comfort. Whether drivers in the real world will actually notice the difference is open to debate.
That reduction in unsprung weight also yields a slight improvement in fuel economy — at least on paper. But the fuel economy argument for PCCBs ranks only slightly ahead of the I-read-Playboy-for-the-articles argument on the credibility scale. And even as the price of premium fuel hovers around five bucks a gallon (knock on the nearest real wood appliqué that it doesn't climb much higher), the $8 grand required to pop for PCCBs could have bought a lot of fuel.
Lightweight CCBs also improve a vehicle's acceleration, but the relationship is not straightforward. Because the brake rotors are, well, rotating, they require more energy to accelerate and decelerate than a non-rotating element of equivalent weight (the aforementioned computer bag, for example). So weight savings in those areas has a greater impact on acceleration than the same reduction applied elsewhere. And again, the benefits are far more likely to be felt on the track than the street.
Some Like It Hot
So, are CCBs merely a high-dollar gimmick? Not at all. In fact, they offer some significant advantages over old-school cast iron.
For example, ceramic composite rotors are extremely durable. In fact, manufacturers claim that they'll never need replacement — at least with "normal" driving. They're also resistant to the kind of warping that leads to pedal pulsation — merely an annoyance in the "real world," but a noticeable performance issue on the track.
Plus, those in the know at least will be impressed when they see that you're running discs that look more like stone than iron. And for onlookers who need a decidedly less subtle hint, Porsche's PCCB option includes bright yellow calipers on all four corners. The looks of these brakes alone will stop traffic.
The single greatest benefit of CCBs, however, is their resistance to brake fade. With repeated use — especially at high speeds — brake temperatures can rise dramatically, causing performance to drop off. This is a common occurrence during racing, but can also occur if you ride your brakes down a long mountain grade rather than downshifting to take advantage of engine braking. In either case, the consequences can be disastrous. Unlike conventional brakes, CCBs are designed for outstanding performance at very high temperatures. Unless you're spending your weekends at the track, however, you probably won't be pushing your über brakes hard enough to find out just how great they are. And if you do manage to find out on the street, no need to brag to all your friends — they'll know all about it from the evening news.
We Are Living in a Material World
Now, about those brake pads. Today, many OEMs are using ceramic brake pads. But there's a big difference between ceramic pads and CCBs. Price, for one thing. Remember, the ceramic composite rotors make up a substantial part of the overall cost of CCBs.
"Ceramic" has become a buzzword in the highly competitive field of aftermarket brake pads as well, especially those aimed at weekend warriors. Lots of people are switching to ceramic pads for performance reasons (for example, track or autocross use) with, it seems, mixed results.
Almost any pad that will outperform the factory original at the track will be hard on rotors. These pads may be noisy and wear quickly as well. In other words, they're designed to do only one or two things well — at the expense of all the rest. The OEM components, on the other hand, are required to meet a wide range of requirements before they make their way into production. Deviate from the factory pads and you run the risk of upsetting an unexpectedly delicate balance. Engineering 101 is all about trade-offs.
The Future Is Not Now
According to the dealership service managers (representing a range of manufacturers) contacted for this story, CCBs have so far been largely problem-free (excellent performance, minimal wear and brake dust). The only issues reported have had to do with low-speed, low-temperature conditions — such as those you might find while pulling out of your driveway in the morning. Under these conditions, some drivers report a slightly "grabby" feeling to the brakes, as well as some squeal. The cure? Warm 'em up.
If CCBs are so great, why is their availability so limited? As we approach the ninth year in the post-CCB world of production cars, many people are eager to see this trick technology trickle down to the budget-friendly end of the market. So far, though, any signs of that trickle have been little more than mirages.
Germany's SGL Carbon, which worked closely with Porsche to develop PCCB, is eager to bring the technology to a larger market. According to an SGL report, total capacity for ceramic composite discs last year was in the neighborhood of 35,000 (roughly the daily output of cast-iron discs from a medium-size foundry). But by 2011, they hope to be producing 200,000-300,000 units annually at a newly built factory. Even so, the company's "medium-term" plans are geared toward vehicles priced above €80,000 (approximately $125,000).
The greatest remaining cost hurdles have to do with the labor-intensive processes involved in the production of CCBs. "Some of these processes don't yet exist," notes Hans-Michael Güther, managing director of SGL Brakes GmbH, "and others are just at the pilot plant stage."
Like many in the industry, Steve Ruiz, director of engineering for California-based StopTech, a supplier of high-performance aftermarket brake upgrade systems, is reluctant to talk specifics. When asked about when we can expect to see CCBs on vehicles in the $25,000-$30,000 price range, Ruiz — who works closely with the OEMs — says, "It is hard for us to predict. If anyone did so, they would risk revealing a lot about what they are working on.... We are not ready to, and I do not know who is."
Perhaps all we can do in the meantime is be patient. After all, it took more than 20 years for CCB to move from the F1 circuit to the showrooms.
There is a precedent, however. Those "paddle shifters" on the Saturn Aura? That's right; they first appeared on a F1 racer.