daveo4porsche

this is not true - note C&D test with identical 911's and less than 1 ft different after 35 attempts from 100 mph - the 10 ft claim comes from Brembo's website (the maker of Porsche's PCCB's) but they do not state what steel disc brakes they are comparing to - I doubt it's Porsche's steel brakes.

PCCB"s are good for:

1. lighter
2. no brake fade ever - not that fade is a problem with porsche steel brakes
3. no brake dust
4. better appearance
5. longer life for street driving

rj2014

I looked at a Chalk Cayenne with the high gloss black sport design package in person a couple of months ago and it looked stunning. The configurator does not do a good job of showcasing it. But again, looks are very subjective so try to see one in person if you can.

CanuckGT4

Oh here we go again. the guy with the agenda.
Won't believe the manufacturer because of some google searches and personal stories. Also asserts that brembo is not comparing pccb on a porsche to steel on a porsche, really? I think that assertion says more about someone else's mindset.
Also doesn't believe a head-head comparison of the same vehicle, tires doing braking test. Never good enough for him, but he has all the answers of course.
You like to do math, try this on for size.
What was the best braking distance quoted for a 911 carrera S, 28 meters? You take issue with is being steel brakes or ceramic right? Ok, let's assume that's ceramic brakes. So according to the manufacturer, the best steel brakes braking distance would be 31meters because 3meters(10 feet) is what the manufacturer of the brakes says is the improvement you will notice. 3/31 = ~10% shorter stopping distance vs almost 11% if you assume 28m is with steel, which is highly unlikely. Does that 1% make you feel better?



And where is this C&D test you like to refer to?

I note you take no issue with how the test was performed ie., age of brakes, condition of tires, what brand of tire, all the things you took issue with in the video that clearly shows an advantage. i wonder why the lack of rigor here? hmmm

daveo4porsche

you have a poorly done video with with a Cayman steel brake vehicle with brake fade after only 10 tries and an unqualified statement from brembo saying 3 meters vs. steel brakes but no indication of which steel brakes.

I have years of actual driving experience, physics and a C&D test w/data that shows two 911’s with identical tires and 35 back to back trials from 100 mph shows 1 ft or less variance between the 911 with steel vs. PCCB.

you can’t make the statement that PCCB’s will stop a Cayenne in 10 feet less - you have no data to prove that and Porsche makes no such claims.

daveo4porsche

ok I found the link about your 10 foot improvement:

ok I found the link - not the title - BREMBO BRAKE FACTS FOR FORMULA 1 BELGIUM

https://www.thespeedjournal.com/brem...217;s%20driven.

what is vague here is “traditional disc” - are Porsche’s excellent steel brakes considered “traditional discs?” - traditional disc are neither vented or drilled - and PCSB’s certainly aren’t the target comparision - and they are talking about this in the context of an F1 car which has no ABS system which actually can increase stopping distance because it will pulse/release the brakes at the tire’s grip threshold…

and it’s referenceing the differences in braking distance on a F1 car vs traditional “cast iron brakes” - I’m going to state F1 braking data with NO ABS system (F1 cars do not have ABS systems) and they run full slicks is proably not applicable for a Street car with ABS and non-slick tires…

that data transfering to a street car is laughable.

but you can believe it if you want.

I’ll state for anyone reading it you can NOT expect any stopping distance improvements with Porsche Steel Brakes vs. PCCB’s unless the Porsche Steel brakes are thermally stressed. And C&D braking test of two identical 911’s found a 1 foot difference between Porsche Steel brakes and PCCB’s in 35 trials in a row from 100 mph - and they encounted no brake fade on either the steel or PCCB’s

but yeah if you want to believe that PCCB’s can magically make your ABS equipped vehicle with street tries stop shorter you’re welcome to your delusion.

CanuckGT4

People can decide for themselves.
Real world testing is more important that arguing about numbers. He found a 5m improvement, wow.

daveo4porsche

against a Cayman T on smaller tires that had brake fade after less than 10 trials - if your Cayenne steel-brake vehicle has serious brake fade after 10 trial stops from 80 mph then yes PCCB’s will be an improvement. Note Porsche own testing of all their brakes (STeel & PCCB’s) require the vehicle have no brake fade after 25 trials from 80% of top speed - this video is no where near 80% of top speed - so again decide for yourself - this video’s results are in direct conflict with Porsche’s own internal design and testing standards for vehicle brake system design.

and the improvement can be explained by a 1/8th of a second difference in reaction time.

but yes 100% yes - IF YOU CAN GET YOUR CAYENNE TO EXPERIENCE Brake fade after only 10 trials then PCCB’s will be better - no question.

to call the testing methodology here “loose” is an understatement - so yes people can decide for themselves.

daveo4porsche

here is the Car & Driver test with data and repeatable results where they found NO DIFFERENCE between two identical 911’s one with Steel and one with PCCB’s and also found even from 100 mph they found no fade with the stock steel porsche brakes.

https://www.caranddriver.com/feature...power-to-stop/

yes people can decide for themselves

a poorly done video with no data and a Cayman that doesn’t match anyone’s experience

or a through review across multiple cars - 300 stops performed form 100 mph and results that are qualified and repeatable - and the fact that no vehicle can stop faster than it’s tire’s maximum grip threshold regardless of the brakes (physics)

so yes please decide for yourself.

daveo4porsche

https://rennlist.com/forums/cayenne-...l#post17639112

I found something relevant from a Car and Driver performance brake test. Two identical 911’s with identical tires; one with PCCB and the other with iron brakes:
Not surprisingly, the Corvette and the two Porsche 911s performed very well in this test. We grew weary trying to the get their brakes to fade. All three cars survived more than 35 back-to-back stops from 100 mph without a decrease in performance. That feat is even more amazing when one considers the relatively brief 20-second interval between stops.

The 911 with the PCCB system performed about the same as the other 911 and the Vette. The average stopping distances of the two 911s were within a foot of each other (305 feet), not surprising since both cars were wearing the same tires. The Corvette averaged 326 feet. The conclusion: PCCB buyers enjoy a 37-pound weight savings but not necessarily more robust brakes.
Tires stop the car. Brakes stop the tires.

C&D video and article posted above - the emphasis concured with the body of evidence

the only data we have claiming PCCB stopping distance advantage for cold brakes is the video posted above by @CanuckGT4 which requires you to believe a Cayman T’s Posrch steel brakes will fade after 10 stops from 80 mph - that’s low end honda level performance right there - not the sort of behavior you expect from Porsche’s steel brakes - and conflicts with C&D instrustmented tests where 911 w/Porsche steel brakes suffered zero fade in 35 back to back tests from 100 mph and 20 seconds between tests…and conflicts with Porsche’s own braking standards.

CanuckGT4

Interesting. Even Porsche claims "exceptionally short braking distances". Seems odd to mention that if all their braking systems have identical braking distances.
I think those Porsche engineers need to visit rennlist more often so they can better educate themselves.

The Porsche Ceramic Composite Brake with yellow-coated aluminium fixed calipers is the ultimate upgrade for your Porsche. These larger cross-drilled brake discs provide considerably greater power, for exceptionally short braking distances, maximum braking safety and greater control in extreme driving situations. The ceramic brakes are also 50% lighter than grey cast iron discs, which enables better grip, greater driving and ride comfort, and more agility.
https://www.porsche.com/canada/en/ac...riginalbrakes/


Now one thing that hasn't been mentioned is the SIZE of these discs. They are massive. Perhaps that explains any difference in braking distance, that would make sense to me.
Larger surface area to grip with those monstrous 10piston calipers slows things down faster.
The only data I would like to see is the coefficient of friction between the pads and disc for all their braking options per square mm/in or whatever they use. That would tell the whole story and settle it once and for all!

ace37

No offense at all, but that can’t make any difference at all for a single stop or a few sequential stops where thermal performance isn’t challenged. And when the pad coefficient of friction is low or high, you’ll just press the brake pedal harder or more gently and give it more or less force to offset the different coefficient, so pad friction is a matter of braking feel rather than stopping performance. The clamping force seems to be a common misconception so I’ll explain that more. And again, I mean no offense here.

If the brakes grab firmly enough to successfully trigger ABS, then how fast you stop (or how short your stopping distance is) is a matter of the friction between the tires and the road. The brake calipers press the pads to grab the rotors so hard that the tires want to lock up and skid, so the ABS system is actively backing the calipers off and managing their clamping force to get closer to the ideal maximum friction and maximum braking performance in terms of stopping distance. If the calipers can clamp the rotors with additional force beyond what the ABS system calls for, it won’t change anything because the ABS system won’t ever use that extra clamping force.

If you wanted to assert that the PCCB ABS logic is better because Porsche developed it more to differentiate the PCCB system’s performance, you could get away with that argument. That would improve stopping performance. But as a bunch of people bantering on the internet, we won’t be able to test out the claim, so it would be pretty hollow.

I like the PCCB system’s weight savings, no dust, and they look nice. They do have some clear and well understood upsides, and ignoring the costs they don’t have much downside. So if you get them, enjoy!

Fang911

Wouldnt driving an SUV year round in the snow belt significantly increase the risk of damaging the ceramics (ie a rock in the snow / slush gets caught between the pad and rotor)? It doesnt take much for this to happen on GT3’s etc and the ceramics are damn expensive to replace-

daveo4porsche

PCCB’s have superior friction and as we know vastly superior thermal characteristics - but those characteristics don’t matter until you’re into use cases where you’ll overheat Porsche’s excellent steel rotors - almost impossible to envision street driving ever doing this - track usage maybe

but as @ace37 carefully explained both Steel and Ceramic brake surface friction is vastly more than tire grip and ABS will therefore “release” the brakes to avoid tire’s locking up - this is why your stopping distance is governed by your tire grip - the brakes level of maximum grip is irrelevant if your ABS system is “working against you” and pulsing your brakes to keep the tires at the grip threshold - which is exactly what it’s doing.

Porsche’s claim is carefully worded:

”for exceptionally short braking distances”

porsche avoid the use of “shorter” - the same claim can be made about their steel brakes - they are engineered for the minimum possible stopping distance - this is true of all Porsche braking systems and is governed by the amount of tire grip and ABS system behavior pulsing the brakes when you approach tire grip thresholds.

the same claim could be made of MPG - “for the best possible milage” - they certainly did not engineer the PCCB’s to offer “exceptionally long braking distances”

PCCB’s will stop your porsche in as short a distance as possible and that the ABS system and tire grip allows - physics.
so will their PCSB’s
so will their steel brakes
all will be about the same until you reach thermal saturation

_IF_ PCCB”s do stop shorter I would venture it has more to do with the fact that bigger tires that are standard with PCCB’s that have more contact patch area (surface area for grip) account for any differences - and if you normalize the tires as the C&D 911 testing did - you’ll find virtually no meaningful difference in stopping distances.

_IF_ your steel brakes are thermally saturated - well then PCCB’s will offer vastly shorted stopping distances because they will not be “full of thremal juice” and will maintain their high co-efficient of friction under much much much more difficult thermal circumstances.

https://www.porsche.com/usa/accessor...riginalbrakes/

Porsche engineering in multiple interviews has confirmed their brake torture test - and all porsche brakes conform to the 80% top speed 25 times in a row with no fade design goals. This alone sets porsche apart from other vendors in that they actually design/test their braking systems to these sorts of no-fade standards which will in fact optimize braking performance across their product line.

there is no debate that PCCB’s are better brakes - but they are better in a way that can’t possibly matter in any legal driving circumstances and barely matter for any track driving short of endurance racing. It’s more of a testiment to how good Porsche’s steel brakes are rather than an inditement against PCCB’s - there is no question porsche PCCB’s offer superior performance fade reistance and compared to most vehicles both Porsche Steel and PCCB’s are demonstrabiliy superious with many cars driven off the lot having braking systems that can induce serious brake fade in 7 or less high speed deceleration runs - compared to those brakes (97% of vehicles on the road) the PCCB’s are a revelation - but compared to Porsche’s Steel brakes they only offer greater fade resistance.

if tire grip were not a factor and brake friction was a factor there would be no difference in stopping distances in the wet vs. dry. but when it’s wet your brakes remain the same and are quickly dried and yet your tires lose a lot of grip - so your stopping distance increases - if you go in the dry on a hot sticky day and get a really really sticky road surface you can decrease your stopping distance - road surface makes sooooo much difference - combine road surface grip + excellent tire grip + large contact patch + sticky rubber - and your prosche steel brakes will stop your vehicle in a phenomenally short distance - stunningly short - and they will not overheat doing it like soooo many other brakes would.

daveo4porsche

Porsche’s torture test described in this article:

https://www.roadandtrack.com/new-car...n-huge-brakes/

all of porsche braking systems _MUST_ pass this test - and given they require specificed deceleration g’s to be maintained across the 25 trials - there can be no change in stopping distance allowed - which is why the video with the Cayman T showing brake fade is questionable - there is no question that Cayman T was experience brake fade, but there is a question as to why with only 10 trials from 80 mph - that would ‘fail’ porsche specififications.

the key quote is here - any brake fade after a few trials would show up in dramaticly reduced g’forces under braking which would elongate stopping distances - fewer g’s equal less deceleration equals more time rolling and covering distance equals longer stops from the same speed - Porsche normalizes their brakes to maintain consistent g’s and therefore brake performance for 25 times in a row - no porsche with any of their brakes should experience _ANY_ brake fade until you are beyond the testing standards - 25 trials in a row with no break between trials. Not sure how you decelerate from 80% of top speed 25 times in a row with no pause for brake cooling in any street situation - but I welcome examples.

CanuckGT4

so no comment on porsche's claim that pccb stop you quicker than other brakes? i think you've reposted this same stuff many times over.
do you type it all or just copy/paste?