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There are hundreds of threads debating whether your should be ordering a Porsche with pccb or not, or if you should convert to iron from pccb, or if you should consider upgrading to pccb if you have standard iron brake.
Some argument are more obvious like cost, durability, dusting, squeaking etc. but these are not the intention of this discussion, as they are all subject to one's opinion and that's why the debate is going to continue, and when it comes to that decision you may still be struggling whether you should "pccb" or not "pccb".
So today I am going to present a deciding factor that is objective and quantitative, with the analysis of Moment of Inertia between two brake rotor materials, to prove the advantage of a light weight rotor such as pccb which might be helpful to your decision when "that time" comes again.
A quantity expressing a body's tendency to resist angular acceleration.
It is the sum of the products of the mass of each particle in the body with the square of its distance from the axis of rotation.
Last edited by RacingBrake; 04-12-2017 at 10:55 AM.
OE iron rotors design is not the same design as shown (RB), but they were simulated to have the same weight as OE.
OE pccb is an optional upgrade come with yellow calipers
RB-CCB is a system developed by RacingBrake for a 100% bolt on conversion for iron or pccb for easy and low cost on consumable such as pad and rotor discs.
As you can see from above table the advantage of installing a CCB brake, for example if you are to install 394/390mm RB CCB brake system your required effort to accelerate/decelerate is only 1/2 of a standard iron set up even with overisze rotor in the front, while if you adopted to pccb with 410mm in the front it requires 68% of the effort.
Last edited by RacingBrake; 07-22-2017 at 01:45 PM.
OE iron rotors design is not the same design as shown (RB), but they were simulated to have the same weight as OE.
OE pccb is an optional upgrade come with yellow calipers
RB-CCB is a system developed by RacingBrake for a 100% bolt on conversion for iron or pccb for easy and low cost on consumable such as pad and rotor discs.
As you can see from above table the advantage of installing a CCB brake, for example if you are to install 394/390mm RB CCB brake system your required effort to accelerate/decelerate is only 1/2 of a standard iron set up even with overisze rotor in the front, while if you adopted to pccb with 410mm in the front it requires 68% of the effort.
For that summary to be any use we need to work out what the % change is including the wheel, tyre, wheel nuts, hub and any other rotating bits. It could be that a pound foot or two is a drop in the ocean.
The scope of discussion, as the thread title suggested, is focused on the difference in rotor material (CCB or Iron), under this scenario we must assume everything else (Caliper, pad, tire, rim etc.) stays the same (as constant).
It's not the intention of this discussion to go beyond the subject title, nor to ignore how other components play the role in the overall effect, so we prefer to keep our focus on this subject only.
Thank you.
Last edited by RacingBrake; 04-12-2017 at 04:02 PM.
Your opening post states that this discussion is aimed at choosing PCCB or not when the time comes. Then you go on to discuss the difference in rotating inertia. You can't inform the buying decision without understanding the impact of this difference.
Was intrigued so attempting to answer my own question. Don't have all the surface area data so will err on the side of caution. Rear wheel weight est. at 25lbs plus tyre weight is 31lbs for MPSC2. MOI is this weight multiplied by the average distance of the weight from the centre of rotation. Tyre diameter is 27". The weight of wheel and certainly tyre is towards the edge. Let's guess at 4" down from that, giving a radius of 0.8ft. This gives a MOI of 36 to add to the brake MOIs. This gives an % effort at 93.3% for the PCCBs and 93.2% for the aftermarket ones. Note I haven't included the wheel nuts and hub as they are pretty close to the centre so have less impact.
Was intrigued so attempting to answer my own question. Don't have all the surface area data so will err on the side of caution. Rear wheel weight est. at 25lbs plus tyre weight is 31lbs for MPSC2. MOI is this weight multiplied by the average distance of the weight from the centre of rotation. Tyre diameter is 27". The weight of wheel and certainly tyre is towards the edge. Let's guess at 4" down from that, giving a radius of 0.8ft. This gives a MOI of 36 to add to the brake MOIs. This gives an % effort at 93.3% for the PCCBs and 93.2% for the aftermarket ones. Note I haven't included the wheel nuts and hub as they are pretty close to the centre so have less impact.
exactly.
i asked myself often why rims are only measured in mass. important for the unsprung mass fully ok - but they should be also meassured in MOI. because of better steering and accelerating/braking.
Originally Posted by Richard.
get PCCB but also get somebody else to pay for it new first
this.
interesting would be how many buy PCCB based on the color? 3 outof 5!?
Whats the torque = I x alpha and the calculated Hp difference. Porsche don't list a 0-60 difference between PCCB and steel, so it's probably in the noise. The other benefit would be unsprung mass, but again unless there are different suspensions or suspension setting between the two options I'd say it's in the noise as well.
04-12-2017, 10:11 AM
Pccb or not pccb - Read this first
