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    Ceramic Composite Brakes (PCCB)

    Anyone have an opinion as to how much better the Ceramic Composite Brakes are over the stock setup?

    Define better

    If you're talking about stopping distances the answer is "no difference" - at least Porsche isn't claiming it.

    If you're talking about fade then the answer is "superior" according to Porsche

    If you're talking unsprung weight then the answer is "superior"

    If you're talking reliability then the answer is "ask the jury when they get back" there are issues apparently with cracking.

    If you're talking cleanliness then the answer is "superior" no brake dust worth speaking of.

    If you're talking costs then the answer is "inferior". Both the initial cost and the cost of replacement ceramic discs is high.

    So the answer depends on your criteria.

    Re: Define better

    I've had a chance to compare the standard brakes vs big reds vs PCCBs and there's no question in my mind that I'd ever be able to get anything other than PCCBs again. Sure the cost is high but the overall performance improvement makes it well worth it. The brake pedal feel is awe-inspiring matched by none. The cost of the ceramics from Porsche is actually quite reasonable if you were to compare it with offerings from Ferrari for example.Ultimately it comes down to what you can afford.

    Re: Define better

    Normal everyday use ... you'd never see the performance benefit of PCCB.

    Longevity is w/o question, but the replacement cost is high.

    If you're pushing the car, yes, you'd see the benefits of PCCB - but even then, how often/much are you pushing the performance envelope.

    Re: Define better

    On every day use you need to take care also about correct use. For example never hard brake if they are too cold otherwise the wearing ratio reaches very high levels.
    It's not mathematical that they last longer. They should be used and not abused

    Re: Define better

    Silvershadow, where did you get this idea from?

    Re: Define better

    The standard 'Big Red' brakes on the Carrera are excellent in everyday driving and when pushing it in the twisties. There has never been a time where the brakes were anything less than perfect. The big downside is the brake dust. Your wheels are filthy within minutes.

    I have never driven a car with ceramics disks, but I will consider them on my next purchase, solely because of the brake dust issue.

    Re: Define better

    Quote:
    Heist said:
    Normal everyday use ... you'd never see the performance benefit of PCCB.



    I disagree. The pedal feel and therefore modulation on the PCCBs is better than on the std. brakes and noticeable under average driving conditions already. I tend to believe that Porsche set up those brakes deliberately that way, to provide an advantage over std. brakes. On a Carrera or Turbo, the tires are the limiting factor in terms of braking performance, not the brakes themselves.

    If you'd choose a GT3, equipped with sport or semi-slick tires and driving regularly on track days, the story might be different. However the cost of replacement is much higher for the ceramic rotors and they surely'd have to be replaced in that case sooner or later.

    Bottom line, if you tend to keep the car for a few years, intend to use it primarily on the street and appreciate a superior and steady brake feel (and the other above mentioned advantages), get the ceramics. On some markets however, although being an advantage at resale, they will not fully pay off, just as the X51 powerkit. If you tend to keep the car for a few years and

    Re: Define better

    Where do i get my ideas from? I've worked on cars with ceramic brakes and this was what came out during our normal road tests with test drivers.

    Re: Define better

    I do admit that because these ceramics are much more sensitive than steel brakes (i.e. active the second you press the pedals) they'd be tricky to modulate while doing heel/toeing.

    Re: Define better

    I love my PCCB brakes. The biggest advantage is the unsprung weight, which is very noticeable in everyday driving. It improves handling and acceleration. Lack of brake dust is also very impressive. Lastly, at my 40K mile service the dealer commented on how the rotors and the pads were like new, still. I bet the rotors will last the life of the car and the pads to 100K miles based on the dealers best estimate. No more IRON rotors for me, thank you. Now I am looking for some really light weight wheels to maximise the less unsprung weight advantage - that to me is the key area to lose weight. Someone on this forum had an interesting formula that compared saving unsprung vs. sprung weight. Each pound of unsprung weight saved was equal to 5 pounds of sprung weight. The net effect of PCCB turned out to be about a 20 hp advantage - nearly equal to X-51 in terms of power to weight and much cheaper - better gas mileage too.
    I believe that while you may not get it all back in resale it will certainly add much apeal to the car when it comes time to sell now that reliability and longevity on a street 997 with PCCB is no longer an issue like it was with Gen1 PCCB.
    Just my biased opinion of course.

    Re: Define better

    Quote:
    Leawood911 said:Someone on this forum had an interesting formula that compared saving unsprung vs. sprung weight. Each pound of unsprung weight saved was equal to 5 pounds of sprung weight. The net effect of PCCB turned out to be about a 20 hp advantage - nearly equal to X-51 in terms of power to weight and much cheaper


    Unsprung weight vs. Sprung weight does not matter with regard to acceleration (just handling and ride quality). The benefit of PCCB with regard to acceleration comes from the fact that it's rotating mass. It's a similar effect to using a lighter flywheel on the engine (which is sprung mass).

    Re: Define better

    I have totally seen the light also. I won't buy another sports car now unless it has ceramic brakes.

    Re: Define better

    does anyone of you has racetrack experiance with PCCB?

    The Cup cars don't use PCCB. Many people i know who are driving porsche-cup or sports-cup don't use PCCB neither.

    I heard the wearing ratio is increasing significantly if the temerature is getting to hot, while drifing on the race-track.

    Re: Define better

    Quote:
    silvershadow said:
    On every day use you need to take care also about correct use. For example never hard brake if they are too cold otherwise the wearing ratio reaches very high levels.
    It's not mathematical that they last longer. They should be used and not abused



    I would have gotten them if I could have afforded them, at my time of purchase (late October 2005, delivery in February 2006), but I am satisfied with the one's I have on my 911S. When I hit the brakes, they really slow the car down.

    Yes, they are a pain in the neck to clean, but they work quite well. If I went on the track a lot, then I'm sure the PCCB's would have been the better choice.

    If you track (or plan to) track your car a lot, get the PCCB's. If not, then don't.

    Jim

    Re: Define better

    Quote:
    Jim48 said:
    If you track (or plan to) track your car a lot, get the PCCB's. If not, then don't.


    Many track drivers prefer the iron brakes, since it's easy to damage a rotor with frequent wheel/tire changes or if one should run into a gravel trap.

    Also, frequent track use means you will most likely need to replace rotors due to wear at some point (over $20k). This is far less likely for a street-driven car.

    Re: Define better

    I heard people change back to steel brake when they get into track. In that case, why get pccb? for daily use? you don't need it for daily use. But always, you have more money, everything can be better.

    Re: Ceramic Composite Brakes (PCCB)

    Well, I just got off the phone with the local Porsche dealer who informed me that changing my stock binders for Ceramic Composites is going to cost north of $20K. The kit alone is $18300. The red ones are looking mighty good right now!

    Re: Define better

    Quote:
    Grant said:
    Quote:
    Leawood911 said:Someone on this forum had an interesting formula that compared saving unsprung vs. sprung weight. Each pound of unsprung weight saved was equal to 5 pounds of sprung weight. The net effect of PCCB turned out to be about a 20 hp advantage - nearly equal to X-51 in terms of power to weight and much cheaper


    Unsprung weight vs. Sprung weight does not matter with regard to acceleration (just handling and ride quality). The benefit of PCCB with regard to acceleration comes from the fact that it's rotating mass. It's a similar effect to using a lighter flywheel on the engine (which is sprung mass).



    Less unsprung weight certainly does impact acceleration, sorry (In fact you make the same point in your statement although you are correct that a flywheel is not un-sprung weight)

    The more mass an object has, the more energy it takes to accelerate it. To accelerate a rolling object such as a wheel, you must both accelerate its mass plus overcome its rotational inertia. As for braking, you must overcome its rotational inertia plus decelerate its mass. By reducing the weight of the vehicle's rotational mass, lightweight wheels/brakes provide more responsive acceleration and braking.
    The effect of rotating mass can be calculated using Moment of Inertia (MOI). MoI is related to not only the mass of the rotating object, but the distribution of that mass around the rotational center. The further from the center, the higher the MoI. The higher the MoI, the more torque required to accelerate the object. The higher the acceleration, the higher the torque required.

    Because of this, the weight of rotating mass such as wheels, tires and rotors on a car have a bigger effect on acceleration than static weight such as on the chassis on a car.

    The use of PCCB reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of carbon ceramic brakes on vehicle performance cannot be overlooked.

    Peace

    Re: Define better

    Quote:
    Leawood911 said:Less unsprung weight certainly does impact acceleration, sorry (In fact you make the same point in your statement although you are correct that a flywheel is not un-sprung weight)


    I never said having less unsprung mass wouldn't help acceleration - I said it's the same as having less sprung mass.

    Re: Define better

    I predict that the price of PCCBs will come down,--at least production costs. As such, replacing the rotors years from now when I have amassed some 200,000 miles on my 997S, the costs will not be that bad,--considering that I will have avoided several rotor and pad changes common to today's iron brakes.

    Dan

    Re: Define better

    Quote:
    Leawood911 said:
    Quote:
    Grant said:
    Quote:
    Leawood911 said:Someone on this forum had an interesting formula that compared saving unsprung vs. sprung weight. Each pound of unsprung weight saved was equal to 5 pounds of sprung weight. The net effect of PCCB turned out to be about a 20 hp advantage - nearly equal to X-51 in terms of power to weight and much cheaper


    Unsprung weight vs. Sprung weight does not matter with regard to acceleration (just handling and ride quality). The benefit of PCCB with regard to acceleration comes from the fact that it's rotating mass. It's a similar effect to using a lighter flywheel on the engine (which is sprung mass).



    Less unsprung weight certainly does impact acceleration, sorry (In fact you make the same point in your statement although you are correct that a flywheel is not un-sprung weight)

    The more mass an object has, the more energy it takes to accelerate it. To accelerate a rolling object such as a wheel, you must both accelerate its mass plus overcome its rotational inertia. As for braking, you must overcome its rotational inertia plus decelerate its mass. By reducing the weight of the vehicle's rotational mass, lightweight wheels/brakes provide more responsive acceleration and braking.
    The effect of rotating mass can be calculated using Moment of Inertia (MOI). MoI is related to not only the mass of the rotating object, but the distribution of that mass around the rotational center. The further from the center, the higher the MoI. The higher the MoI, the more torque required to accelerate the object. The higher the acceleration, the higher the torque required.

    Because of this, the weight of rotating mass such as wheels, tires and rotors on a car have a bigger effect on acceleration than static weight such as on the chassis on a car.

    The use of PCCB reduces rotational mass. This means that less energy will be required to accelerate the wheel. Given that each pound of rotational mass lost provides an equivalent performance gain as a 10 pound reduction in vehicle weight, the benefits of carbon ceramic brakes on vehicle performance cannot be overlooked.





    You appear to be overlooking the fact that not all unsprung masses are rotating masses.

    A hub carrier is an unsprung mass, but it is not a rotating mass, so its effect on accelaration is pound-for-pound weight exactly the same as a sprung mass.

    Re: Define better

    The PCCB seem well suited to the Nordschleife which has no gravel pits (crashing into the armco may not damage the rotors ) and is not as brake intensive as many other tracks (thus extending rotor life while enjoying the benefits of less rotating weight).

    Re: Define better

    On the unsprung <-> Sprung, Rotational <-> Non-rotational masses:
    I guess what Grant tries to say is that in terms of acceleration, there is no difference between unsprung and sprung mass. Sprung vs. unsprung only affects handling (Isn't it?) For rotational mass, there is (as Leawood explained) this affects acceleration more than an equal amount of non rotational.
    Summarizing this, it would appear that the lighter brake discs, which are both unsprung and rotational, would affect both handling and acceleration. Correct?
    -Joost-

    Re: Define better

    Silvershadow, interesting. What cars and what generation of PCCB's? Were they SGL or Brembo? Any differences?
    What were the conclusions in terms of heating up the brakes? What real-world longevity did you see?
    Thanks very much.

    Re: Define better

    Hi MarekN, the cars i've worked on were equipped with brembo ones but, considering we benchmarked also other cars on the market, we tested SGL ones as well.

    The main problem of a Carbon ceramic brake is the working temperature of it that should reside in between 300 and 900*C. Optimal working temperature is normally around 550*C and should remain in that range so to operate them correctly.

    Why carboceramic brakes are much more delicate in track use?
    It's not because of the brakes is more because of the brake ducts. They are most of the times not designed for tracking the car and this means that the venting they provide is low enough so to heat the brakes on road use.
    ==> hard use on the track can easily overheat them. Do you see the wear over them? No it's not possible with a visual investigation since the brakes do not produce dust.

    On the road? it can happen the opposite, especially in situations like this one: switch on the car and drive to the next motorway with traffic conditions so low that brakes are quite never used until a hard brake is needed when running at very high speed ==> very high wear.

    This is the reason why some of the manufacturers are asking for a continuously working preheating system helping the brakes on such cars or other systems that work with the same objective.

    So do they last longer? It depends on the use

    Re: Define better

    Thanks for the neat reply, it makes sense.
    From my experience, the brakes are not completely dust free, but I gather that the dust they produce is from the pads, not the rotors (hopefully).
    Eventhough the rotors are almost diamond-hard, you can still see changing wear patterns on them from the pads. For example, on the front rotors, the surface is very even, but on the back rotors, there are Saturn rings that change from time to time. This could also be a microlayer of pad material.
    When you run a finger over the rotors, you can't feel anything, but you can see visually that the rotor surface is changing.

    Re: Define better

    Quote:
    Joost said:
    On the unsprung <-> Sprung, Rotational <-> Non-rotational masses:
    I guess what Grant tries to say is that in terms of acceleration, there is no difference between unsprung and sprung mass. Sprung vs. unsprung only affects handling (Isn't it?) For rotational mass, there is (as Leawood explained) this affects acceleration more than an equal amount of non rotational.
    Summarizing this, it would appear that the lighter brake discs, which are both unsprung and rotational, would affect both handling and acceleration. Correct?
    -Joost-


    You are correct.

    Technically, reducing unsprung weight (compared to sprung weight) has the benefit of quicker transient response of the suspension. So, everything that benefits from improved suspension performance is made better (handling, ride quality and braking on rough surfaces, since the tire will follow the road surface better and create more friction between tire and road).

    Reducing rotational mass (anything that spins to make the car move) improves acceleration (and deceleration). Examples are engine internals like camshafts, crankshaft, flywheel, transmission internals, drive axles, wheels, hubs, tires, brake rotors, etc.

    Reducing mass that is rotating and unsprung mass does both. That is why reducing wheel, tire, and brake rotor mass is so beneficial.

    For those who don't know, unsprung mass is the mass in the suspension system (everything that moves up and down as the wheels are deflected by road imperfections or the car leans from acceleration forces). Examples are control arms, shocks, brakes, wheels, etc.

    The sprung mass is that part of the car (almost all of it) that is supported by the suspension (springs).

    Re: Define better

    Quote:
    Grant said:
    Quote:
    Joost said:
    On the unsprung <-> Sprung, Rotational <-> Non-rotational masses:
    I guess what Grant tries to say is that in terms of acceleration, there is no difference between unsprung and sprung mass. Sprung vs. unsprung only affects handling (Isn't it?) For rotational mass, there is (as Leawood explained) this affects acceleration more than an equal amount of non rotational.
    Summarizing this, it would appear that the lighter brake discs, which are both unsprung and rotational, would affect both handling and acceleration. Correct?
    -Joost-


    You are correct.

    Technically, reducing unsprung weight (compared to sprung weight) has the benefit of quicker transient response of the suspension. So, everything that benefits from improved suspension performance is made better (handling, ride quality and braking on rough surfaces, since the tire will follow the road surface better and create more friction between tire and road).

    Reducing rotational mass (anything that spins to make the car move) improves acceleration (and deceleration). Examples are engine internals like camshafts, crankshaft, flywheel, transmission internals, drive axles, wheels, hubs, tires, brake rotors, etc.

    Reducing mass that is rotating and unsprung mass does both. That is why reducing wheel, tire, and brake rotor mass is so beneficial.

    For those who don't know, unsprung mass is the mass in the suspension system (everything that moves up and down as the wheels are deflected by road imperfections or the car leans from acceleration forces). Examples are control arms, shocks, brakes, wheels, etc.

    The sprung mass is that part of the car (almost all of it) that is supported by the suspension (springs).



    An additional consideration is the fact that the cited 5 kg weight saving per wheel is a much bigger proporiton of the maybe 30 kg unsprung mass per corner than a total 20 kg per car (4 x 5 kg) as a proportion of a 1400 kg car's total weight.

    This means that the effects of reduced unsprung mass of PCCB brakes on wheel control (and thus handling) are going to be much more perceptible to the driver than the effect on the car's straight line acceleration.

     
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