Trompazo
Member
Yes, there is a reason that the Porsche and Mclaren owners who track a lot, put the Carbon rotors on a shelf and replace them with Iron discs. They essentially dont wear at all at temps seen on the street, but for track days the temps get so much higher that they may last only 6 to 8 days.They just 5-10 times more expensive for 2-3 times longer life. So if you go on track a lot - it's not good from budget perspective.
Also, they have lower convection performance (since they are lower density and it's actually hard to form venting channels in CCB rotors) to cool down between applications. That basically means that average rotor temperature would be higher.
Also they have lower heat capacity (weight is lower) that you need to have a heat energy buffer during single application.
Hotter rotors end up heating pads more although convection from rotor to pad is slower on ccb, but infrared radiation starts to be an issue with very high rotor temperature.
Positives are - less dust, lower unsprung and rotational mass, no rust. So CCB is better for street if money is not an issue. Relatively modern CCB don't have cold temperature problem. High temp pads, whether for iron or for CCB, have lower friction when cold (unless it's some high cost sintered metal pads), but still higher friction than what Tesla uses.
Since Plaid is heavy - it uses more energy to go through the same lap with the same speed. But it also can go much faster on that lap since it's capable of much higher average power than normal cars - hence even more energy.
Most of that energy needs to be radiated and convected by brakes to the air (smaller portion by tires to the pavement and air + by general air resistance + regen recuperation).
It would have to be much larger CCB rotors vs steel and you don't want to go with large wheels on the track - you need a sidewall.
So all in all - CCB is not a better choice than iron for the track.
Now if money is not a problem and you can have proper forced air rotors cooling, CCB might become good enough. And you get an advantage of lower dust, no rust and better suspension performance.
I have a Mclaren 720s, and I am getting Girodisc Iron rotors for it. You add about 10 pounds per corner, but a set if OEM rotors and pads cost about $36,000. So the price gets insane per track day.
Carbon rotors also need to be bigger than irons for the same heat dissipation. There is a reason that Porsche that have the Carbon option have discs that are 30mm bigger than the same car with irons.
In a Tesla, the MPP 400mm rotors would need a Carbon rotor of around 420-430mm to dissipate the same amount if heat. Which means you likely would need 21” wheels, which limits your track tire options.
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