Paul Watson, an experienced Porsche tech with Porsche Australia, had some interesting things to say about carbon ceramic brake discs in a recent interview with Australia’s Wheels Magazine.
According to Watson, Porsche always suggests iron brakes for those owners who do track days, as the carbon discs can degrade when punished and are extremely expensive to replace.
Some track day veterans may already know this, but those who are less experienced when it comes to performance driving, this may be a surprise. Especially when you consider that carbon ceramic brakes are used in top-tier racing categories like Formula 1.
“Yes, ceramic discs can degrade if you’re hard on the brakes,” explained Watson. “Heat build-up will degrade the carbon fibres in the disc, so if you’re doing club days we’d always recommend iron discs.”
The first General Motors production car to offer carbon fiber brake discs was the C6 Corvette ZR1, which used the same Brembo carbon ceramic discs as the Ferrari Enzo. These brakes are standard equipment on the C6 ZR1 – an important fact to consider if you are thinking about picking up a ‘Blue Devil’ second-hand some time in the future.
A more surprising recipient of the high-priced rotors was the fifth-generation Chevrolet Camaro Z/28, which also featured massive Brembo carbon ceramic rotors. The Camaro Z/28 achieved up to 1.5g in deceleration during Chevy’s testing, so these Brembos are still quite strong, even if they aren’t ideal for sustained track punishment.
As you may already know, the only GM cars to offer carbon rotors today are the C7 Corvette Z06 with the Z07 Performance Package and the C7 Corvette ZR1.
There is one other benefit to carbon ceramic rotors: they don’t give off any brake dust. So it seems these performance-focused brakes are better suited to those who hate cleaning dirt and grime off their wheels, rather than those who like to go fast.
In conclusion, if you plan on picking up a GM performance car with carbon rotors, do yourself a favor and swap out those pricy and slightly flimsy discs for some iron ones. Carbon ceramic rotors can last a long time on the road, look cool and prevent brake dust, but don’t hold up well when things get a little hot.
Source: Wheels
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Cadillac discovered this several years ago and they swapped out the carbon ceramic brakes in the 640-hp Cadillac CTS-V for larger brakes made of ones made of metal; this had every car tester saying Cadillac was being cheap and stupid as the talking heads said the carbon ceramic were more efficient and they dissipated heat more faster.
Let’s get some facts in the way.
No matter what brake or rotor you use the will degrade under track use. Brakes and rotors are consumables and they sacrifice themselves to stop you.
Ceramic rotors do disapate heat after and more efficiently hence less heat better braking.
Iron with drilled or in Porsche’s case cast holes are susceptible to cracking and the holes are just for cosmetics. If anything they take metal away from the roto and are less a heat sink.
The true statement is Ceramic Rotors are more expensive but they even with track time will out last the iron rothors by a long shot.
As for dust rotors have nothing to do with dust. Pad create dust and the all do. The higher the carbon content the more black dust. Many Kevlar and carbon fiber pads have a lighter gray dust that does not show as easily. But they still produce dust.
When you stop something has to give and the pads are the designated part to be used up.
Rotors do wear some but very little compared to the pads.
Ceramic Rotors are tested for how much wear by weight.
Thank you Scott3! Saved me from duplicating effort to explain the factual nuances you just drew light too.
I mean, that makes total sense. Porsche has them as standard on the 911 GT2 RS and optional on the GT3 RS, and they’re used in Formula 1. Obviously they aren’t ideal for track use
Either are fine for the track, but ceramic are often swapped for iron for cost alone as their consumable. The main take away, iron rotors are just fine.
Learning consumes brakes. Eventually less brakes means in slow out fast. You would save money learning with iron but the rotors still are consumed learning. Everyone wishes for great brakes. The best are expensive and beyond necessary for anyone that is not a pro. But ceramics are engineered to be safer. Safe is good on track, means you go home with your car whole.
It comes down to this.
Do you want to save money or do you want the best fade free braking force?
There is no right or wrong just two choices and what will satisfy your needs.
If you are going for lap times or racing Ceramic is what you need, if you just want to make low cost laps iron is what you need.
Same applies to tires and shocks. How fast do you want to go is based on how much you want to spend.
That unsprung weight reduction though, you’re saving 100lbs of spinning weight by using carbon ceramic discs. Equates to performance of ~300lbs of weight reduction on the chassis.
The only reason they’re not “good” for track use is money. F1 uses them because money is no object. Casual track use of a corvette, too expensive. You could buy a crate LS9 every time you want to change rotors and pads.
Speed costs money, how fast do you want to go?
Ordered them on my 17 Z06, they still look like new after 10,000 miles and leave no brake dust. Their performance is phenomenal, although a little grabby a lower speeds. They look great and perform great, what’s not to like.
On a street car, you’re probably going to sell that Vette long before you see any appreciable wear on the carbon rotors. You will never build the kind of sustained heat in your brakes that starts to break down the carbon rotors, and at over $3000 per rotor, that’s a good thing. However, the average amateur W2W driver in regard to the J57 carbon brakes is already spending enough for the weekend in tires, entry and travel fees, consumables and fixing what broke to justify risking the replacement cost. Carbon brakes are most awesome in 2 situations – 1. cool factor, street cred and bragging rights and 2. in a racing environment where the budget is measured in millions. Do they offer advantages? Absolutely. Are the advantages enough to outweigh the cost on something short of an F1 or LMP car at the track? Very debatable. The lower J56 brake package on the C7 Z06 and GS already matches or surpasses what many “race cars” were running not all that long ago, and with the right pads is plenty fine on the track. That J56 system in stock form made the list of the 13 best stopping cars ever tested by Car and Driver (as did the J57 of course) and tied the LaFerrari and McLaren Senna. Coupled with a replacement disk cost of under $400 a wheel, there’s a reason that you don’t see many amateur Corvette/Camaro race teams or dedicated track cars running the carbons. Are they awesome? You bet. Are they overkill when the J56 brakes are so good? Depends on your income 🙂
I was talking to the rep from PBR one time at an engineering convention. They provided the braking systems for the space shuttle and on many of the next generation uavs including the unmanned space shuttle. He told me that NASA provided them with the specs for their braking system….they were slotted in a helical pattern. He said they found that there was mass lost but the surface area that was gained allowed for greater heat displacement. He had a figure that kinda stuck with me that for every 10in of slot it was the equivalent of gaining 1/2 of an inch in diameter. That was huge to me. I’m sure that he meant in heat terms not in braking force because you cant cheat physics.
All true. But if you take a $25k car and put $1mil into you will have an amazing race car. Money does not buy better track times, the driver makes better lap times. Be a better driver not a driver who
Just spends more to compensate for lack of skill.
I don’t know about the C8, but through the C7, Corvette Racing used slotted steel rotors without vent holes.
I believe the C7R team as part of IMSA rules isn’t allowed to use anything but slotted steel rotors.
I don’t know about that, but the point is that steel works very well in the toughest of applications, and sometimes exotic components are merely eye candy.
Catbert, the FIA Vipers were the same. Can’t post pics on this page, but I have some from the ALMS cars as well as a couple of the FIA Eurpean Oreca Vipers and can assure that we ran 2 piece ferrous rotors and not carbon on the 2nd gens. Those Vipers taking 1st-6th in GT2 at LeMans in ’99 likely proves they did just fine with them. As for the holes, you’ll not see ANY real race cars with holes in the rotors as long as those rotors are made of steel or iron (carbon shares different properties). They’re nothing but a place for cracks to start. And before someone jumps in with “But Porsche (or insert other exotic car manufacturer name) puts them on their cars, research it. You’ll find out that they don’t recommend them for hard track use and their factory teams don’t run iron or steel rotors with holes. It’s what people want, and it’s become expected aesthetics for high end sports car owners who never see a racetrack. Slots are much better in that regard.
Gah, I hate it when journalists take a comment and then extrapolate stupidly. Carbon/ceramic are NOT flimsy, especially compared to iron – the opposite in fact. The article made it sound like iron rotors never fade! A few things…
1) F1 uses carbon/carbon, not carbon/ceramic. Still, carbon/ceramic is closer to F1 than iron brakes are.
2) Carbon/carbon brakes will never be used on a car that also needs to work on the street as they have near zero stopping power when cold.
3) Carbon/Ceramic is the closest you’ll get to F1 brakes on a production car, and as such are absolutely the BEST brakes for the track when performance is the only consideration. They will be better than any iron setup due to weight & heat, and thus fade. If you get iron rotors so large, and with so much cooling, that you eliminate fade, your unsprung weight will likely be significantly higher now. So carbon/ceramic still wins.
4) Iron only wins on cost, but you also have to replace it far more often – especially on a dual-duty street/track car. Carbon/ceramic doesn’t really wear on the street (because you can’t get it hot enough, and explains the near zero brake dust) and will often go 100K+ miles without even a pad change. Only under extreme track temps does it really wear.
Porsche do recommend iron for track use because of the cost (they don’t want angry customers demanding free brakes). They also use iron in their racing series, again because cost. The racing teams consist of rich and poor teams, so brake costs are a big area to help reduce cost of entry, and they make it part of the rules because carbon/ceramic are a massive advantage that they don’t want the rich teams using! Think about it – if the carbon/ceramic brakes were a disadvantage, why wouldn’t they let teams run it instead of the “superior” iron (some race rules let you do things that have zero effect or are a disadvantage with no penalty).
For the past three years I have only tracked with carbon/ceramic, and it’s been amazing. I can do 30 minute sessions, braking from 150mph, lap after lap, and I get absolutely zero fade. So far I’ve only had to change pads twice, and about to do it a third time this month. I also track a lot (I have at least 4 track days over the next 3 weeks already booked).
Carbon/ceramic brakes blow away every one of my prior iron rotor based cars in the past, and, if your budget can stretch to it, I highly recommend it.
Oh, and as for not making you faster, I have to disagree on two fronts – one you get more laps, thus your track days are better value for money, and you get more practice. Secondly they let you brake deeper consistently, again letting you learn a track much easier without having to worry about brake points changing between two adjacent laps.