Carbon Brakes - walk away or worth it?
Discussion
For the people who have actually driven the same model with and without PPCBs (I own one with and have driven one without), I find it hard to believe the steels are as effective as the PCCBs although I am not arguing. However driving them both the PCCBs seem much stronger.
Even on a recent test drive in a 991 Turbo from the OPC the salesman was telling me about how he usually shows how good the PCCBs are with a stopping demonstration. He said 'This car only has the steels which are not as good" not scientific by any means, but the thought was the PCCBs stopped much better, which is how it 'feels'.
Again I thought the USP is that they are more resistant to fade, hence more popular on racing cars.
Even on a recent test drive in a 991 Turbo from the OPC the salesman was telling me about how he usually shows how good the PCCBs are with a stopping demonstration. He said 'This car only has the steels which are not as good" not scientific by any means, but the thought was the PCCBs stopped much better, which is how it 'feels'.
Again I thought the USP is that they are more resistant to fade, hence more popular on racing cars.
Isysman said:
For the people who have actually driven the same model with and without PPCBs (I own one with and have driven one without), I find it hard to believe the steels are as effective as the PCCBs although I am not arguing. However driving them both the PCCBs seem much stronger.
Basic placebo effect.Most Audi drivers think their overservoed brakes are super powerful because they are short travel and feel like an on-off switch if you like. Which is the very last thing you want for modulation. Yet those guys might be using 30% of the braking power.
It is likely that PCCBs "feel" more powerful because the pedal has a sharper/easier action and/or less travel. Which has nothing to do with performance. It just means that the steel set up needs working harder physically. Which is a good thing IMO if it rewards modulation.
As we all know, 99% of punters going on Porsche driving events will scare themselves at 5/10ths. So no wonder they find the PCCB's performance superior, just because it responds quicker to less effort. But used "properly" the steels will do the same job in terms of performance (but not for as long!!), it's all about tyres.
Edited by nickfrog on Saturday 21st June 16:42
Wow I better seriously change my driving style on my next track day as I have been ignoring the advised braking cone and confidently braking later relying on my PCCB's. I am quite obviously going to kill myself and do harm to others as I've been relying on a misunderstanding about the ability of my brakes. Thanks for heads up guys.
What do people find so hard and offensive about the proposition that their perception might not reflect any actual difference in reality?
I know that my car feels much faster than a 335i, for example, but I don't throw a hissy fit when the numbers say otherwise.
Do you seriously think that every test is wrong and that the science that explains the results (i.e. that tyres and not brakes limit the maximum braking force) is also wrong? Isn't it more likely that what you feel doesn't reflect a real world difference?
I know that my car feels much faster than a 335i, for example, but I don't throw a hissy fit when the numbers say otherwise.
Do you seriously think that every test is wrong and that the science that explains the results (i.e. that tyres and not brakes limit the maximum braking force) is also wrong? Isn't it more likely that what you feel doesn't reflect a real world difference?
nickfrog said:
There are braking cones at the track days you do ? ;-).
It's quite common to have cones to mark the braking points and apexes on some track days. It means that the relative novice can learn the circuit safely.The position of the cone, or 'brake' board, is only a guide - a heavy road going saloon will brake much sooner than a lightweight Caterham or Elise.
nickfrog said:
Or maybe you were too slow getting in the braking zone ? 
Seriously, they really cause more problems than they solve as one guy will ignore them but the guy in front might not. No one is wrong of course but it can lead to big accidental closing speeds.
I just pay attention to what the guys say in the briefing, after all they are at the track on a daily basis.Seriously, they really cause more problems than they solve as one guy will ignore them but the guy in front might not. No one is wrong of course but it can lead to big accidental closing speeds.
As I'm not a driving god or someone who thinks he knows better than anyone else I pay attention to those who I consider know more than me and mostly follow it.
Back on the subject of PCCB's to date I consider them to be a bargain on a secondhand car as the car I bought was no more expensive than the same model/year without. Saucer sized discs on big open wheels just look silly regardless of whether they perform properly, more so on a performance car
I forgot to add I noticed the guy doing the briefing at Castle Coombe was also one of the instructors
Edited by BIRMA on Saturday 21st June 21:49
Edited by BIRMA on Saturday 21st June 21:53
nickfrog said:
Basic placebo effect.
Most Audi drivers think their overservoed brakes are super powerful because they are short travel and feel like an on-off switch if you like. Which is the very last thing you want for modulation. Yet those guys might be using 30% of the braking power.
It is likely that PCCBs "feel" more powerful because the pedal has a sharper/easier action and/or less travel. Which has nothing to do with performance. It just means that the steel set up needs working harder physically. Which is a good thing IMO if it rewards modulation.
As we all know, 99% of punters going on Porsche driving events will scare themselves at 5/10ths. So no wonder they find the PCCB's performance superior, just because it responds quicker to less effort. But used "properly" the steels will do the same job in terms of performance (but not for as long!!), it's all about tyres.
It's not placebo affect, that's nonsense. They are better than standard in my opinion. Most Audi drivers think their overservoed brakes are super powerful because they are short travel and feel like an on-off switch if you like. Which is the very last thing you want for modulation. Yet those guys might be using 30% of the braking power.
It is likely that PCCBs "feel" more powerful because the pedal has a sharper/easier action and/or less travel. Which has nothing to do with performance. It just means that the steel set up needs working harder physically. Which is a good thing IMO if it rewards modulation.
As we all know, 99% of punters going on Porsche driving events will scare themselves at 5/10ths. So no wonder they find the PCCB's performance superior, just because it responds quicker to less effort. But used "properly" the steels will do the same job in terms of performance (but not for as long!!), it's all about tyres.
Edited by nickfrog on Saturday 21st June 16:42
As for the other comment about unsprung weight, ok that's another benefit but having brakes not fading when you've done a handful of laps is vital.
Edited by Isysman on Saturday 21st June 21:51
Edited by Isysman on Saturday 21st June 21:52
No you"re nonsense ;-).
If one cooks Porsche metal brakes in a handful of laps, maybe one brakes too much and should lean on the lat grip instead...
I take it you still haven't taken the car anywhere near a track ? Nor any car for that matter.
If one cooks Porsche metal brakes in a handful of laps, maybe one brakes too much and should lean on the lat grip instead...
I take it you still haven't taken the car anywhere near a track ? Nor any car for that matter.
Edited by nickfrog on Saturday 21st June 22:40
nickfrog said:
No you"re nonsense ;-).
If one cooks Porsche metal brakes in a handful of laps, maybe one brakes too much and should lean on the lat grip instead...
I take it you still haven't taken the car anywhere near a track ? Nor any car for that matter.
It's well known that ceramics are used because they are resistant to fade even at extremely high temperatures. I don't need to use mine on a track to say it here. If one cooks Porsche metal brakes in a handful of laps, maybe one brakes too much and should lean on the lat grip instead...
I take it you still haven't taken the car anywhere near a track ? Nor any car for that matter.
Edited by nickfrog on Saturday 21st June 22:40
If I wanted to track my car I'd have bought a GT3 not a Turbo. Do you actually own a Porsche or are you just a groupie hanging out in Porsche forums?
Edited by Isysman on Sunday 22 June 00:23
Isysman said:
It's well known that ceramics are used because they are resistant to fade even at extremely high temperatures. I don't need to use mine on a track to say it here.
You appear to be confusing them with carbon/carbon brakes which can run at temps way beyond anything else.Carbon ceramic isn't used in racing much. A few instances in spec racing series where its marketing led; Supercup have used it a few times (Carrera Cup doesn't) and Ferrari Challenge has used it exclusively since the 430 (my old 430 challenge had them). Other than that I can't think of anything else. In fact most series outright ban them allowing carbon/carbon and steel only.
The carbon in PCCB type rotors oxidizes at 750 deg and the rotor just floats away. This is the reason for weighing them to determine life cycle. The result is that that they have the same upper temp limit as something like RS29, a common enough track day pad choice.
One interesting side bar is that friction coefficient of the brake never stabilizes with PCCB. It makes braking a lucky dip type of event under racing type use. You never know quite how its going to work for you, making brake markers etc very difficult. Its not a pleasurable situation when you are running things up towards the limit. Not of specific interest to this thread of course.
Edited by fioran0 on Sunday 22 June 02:15
mrdemon said:
it does if the guy in front has PCCB and you don't, as you will just pile into the back of them lol.
but being serious, I buy sports cars and drive them quite fast, the extra performance is nice to have and makes the car a lot safter.
It also allows me to out brake cars with much more power which is great on track, but I like that performance advantage on the road also for that odd 911 driver who has to be on the brakes 30 yards earlier :-)
Depends if you buy cars to pose in or drive I guess.
For the benefit of the late entrants. This is the catalyst for this groundhog day esque clu$terf^*k.but being serious, I buy sports cars and drive them quite fast, the extra performance is nice to have and makes the car a lot safter.
It also allows me to out brake cars with much more power which is great on track, but I like that performance advantage on the road also for that odd 911 driver who has to be on the brakes 30 yards earlier :-)
Depends if you buy cars to pose in or drive I guess.
Stopping distance = velocity ^2 / 2 x deceleration
Deceleration = mu x gravitational constant
mu = tyre friction coefficient.
It should be clear enough surely that stopping distance is thus dependent upon velocity and the interaction between your tyre and the road. Its hardly ground breaking thought that (what tyres/road surface interaction and how fast you are going are what dictate your stopping distance...far out man!!!) but apparently its proved problematic. Since Newton isn't about to ask, there is info that I provided from Michelin thats fairly accessible a few pages back that explain how it all works. Please feel free to pop back and have a read. There are independent test sheets from various cars too that may be of interest when combined with a look at the above equations.
The rules don't suspend just because one disbelieves. Last time I checked PCCB didn't stand for Physics Changing Car Brakes.
Edited by fioran0 on Sunday 22 June 03:34
This is an interesting thread, it has made me re-visit all of the articles on Carbon Brakes that I read prior to buying a car with them. As an enthusiastic driver it would appear I may have overly relied on them, but to date have not come unstuck (excuse the pun) with my very late braking.
I can see how if you are running a dedicated track car steels make sense but for road use they surely make sense particularly on a secondhand car if properly checked out. From my experience there is almost a negative inference to having them when selling the car regarding what I would class as urban myths about having to replace them. If someone was about to buy a car with them it would do no harm to read through this thread, although again from a road car point of view I started a thread asking if anyone had actually had to replace their PCCB's and if I remember correctly no one person did.
I can see how if you are running a dedicated track car steels make sense but for road use they surely make sense particularly on a secondhand car if properly checked out. From my experience there is almost a negative inference to having them when selling the car regarding what I would class as urban myths about having to replace them. If someone was about to buy a car with them it would do no harm to read through this thread, although again from a road car point of view I started a thread asking if anyone had actually had to replace their PCCB's and if I remember correctly no one person did.
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