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Average customers do like low pedal forces. It makes brakes feel stronger.
Depending on the type of motorsports and the driver you'll see recommendations range from 80 lbs to over 200 lbs of pedal force at lockup, the high force allowing for better modulation near the limit of adhesion and therefore faster. This isn't really as much force as it sounds given that you can likely easily lift your body weight on one leg over a small range of motion, but it's far more force than most drivers are used to or comfortable with on passenger car brakes. Porsche used to use forces similar to this, but they have been reducing forces from motorsports normal practice to roughly 1/4 of those values even with their iron brakes (divide the Newtons scale below by roughly 4.5 to get pounds). You can see normal iron brakes are below 30 lbs at 1G of braking, and the difference between .1 Gs and .5 Gs is only about 5 lbs.
Porsche makes it clear this has been in response to customer "pull".
With PCCBs forces are significantly lower still, leading to the complaints about touchyness, added difficulty with heal-toe, etc. It's intentional on Porsche's part- they could easily give PCCB and Iron the same pedal feel, but "people who spend 10k on brakes want to be able to feel the difference". Unfortunately in this case this flies in the face of what motorsports has found to be most effective, but it's going to come down to the driver and their own personal preference. Most are primarily buying street cars, and don't want race car levels of effort.
If this is the case, why do the accomplished racer reviewers like Pobst rave about the PCCB brakes? Hell that guy drives the best cars in the world and he just gushes about the PCCBs.
For me it's not about initial feel, it's the overall pedal feel and my sense of ability to modulate braking pressure. This weekend I went straight from my Carrera into the Cayman and it really sank in how much better the PCCBs feel to me. For me I just have much better feel and fine control over the braking than I sense with the steels. I'd bet most mortals that lived with PCCBs for a week wouldn't want to go back.
If this is the case, why do the accomplished racer reviewers like Pobst rave about the PCCB brakes? Hell that guy drives the best cars in the world and he just gushes about the PCCBs.
For me it's not about initial feel, it's the overall pedal feel and my sense of ability to modulate braking pressure. This weekend I went straight from my Carrera into the Cayman and it really sank in how much better the PCCBs feel to me. For me I just have much better feel and fine control over the braking than I sense with the steels. I'd bet most mortals that lived with PCCBs for a week wouldn't want to go back.
That's precisely the whole point. PCCB **feels** different from steel brakes, but nothing more in practical braking capability.
The PCCB brakes are supposedly superior to steel brakes for non-GT cars due to the significant difference in brake rotor size and 2 extra pistons (at least in 997/987 generation). The larger calipers and rotors certainly help heat dissipation along with the greater braking power due to leverage. However, like most people have already mentioned here and in other discussions, modern Porsches' braking power isn't limited by the calipers, but rather by grip especially on these GT3 and GT4 cars. By going from 6-pot GT-badge steep brakes to ceramics won't actually make you stop faster. In fact, as C&D's short run of stress test shows, even 997 911's 4-pot steel rotors do not out brake the 6-pot PCCB.
So, the question is down to the brake pedal feel. The weight savings, again as presented by others previously in this forum as well, are actually not that big. Walter Rohrl is a world class racer, and he prefers to spec PCCB into his GT4. He probably knows Porsches better than most world class racer. That sorta tells you something there.
PCCB brakes are not race grade brakes. Just because LeMans cars runs ceramic brakes doesn't necessarily mean Porsche is giving you the same brakes for road cars. Again and again, PCCB brakes make you feel the car brakes better simply because of the brake pedal feel. I don't think there is any argument that PCCBs feel different, just that the argument is whether they are worth it for people who care about spending the 8K for the feel + no brake dust yet with no real world braking power improvement. Ceramic brakes will be more resistant to fade on the track under extended periods of use. However, from guys who run their GT3s on the track, the don't seem to experience any noticeable different while running 25 mins sessions. Perhaps the difference is there if you do 45 mins+? But then who actually does that? Not that many people. On top of that, the heat dissipation and marginal weight difference could be achieved by putting in floating discs into the red brakes during brake rotor change ...
Last edited by KingSize.Hamster; 10-07-2015 at 10:23 PM.
That's the thing. You may be eliminating a portion of your potential buyer pool on resale if you spend the extra money to get PCCBs. Many/most track rats buying used will pass on a car with ceramics. Many RLers have made posts to this effect.
No one, at this point, knows the replacement rate and costs of the Gen 3 PCCBs.
Everyone who says they are more expensive to use on track than iron rotors are basing their calculus on the Gen 2 PCCBs.
I've read many sources that say that the steel breaks are from the GT3, and are already over sized and overkill on the gt4, so what's the point of getting the ceramics when the stock steel breaks are that good, already overkill.
The price of the ceramics is crazy, out of this world.
Agree, I'd rather spend the money on a nice watch or any number of things, like a very nice hot tub to enjoy daily.
If this is the case, why do the accomplished racer reviewers like Pobst rave about the PCCB brakes? Hell that guy drives the best cars in the world and he just gushes about the PCCBs.
There's no question both brakes are great. There is also no question that opinions on feel vary, or that motorsports brake pedal forces are in fact massively higher.
It terms of feel I suspect preferences differ in part depending on personal experience and what direction you're coming from. A few data points, however:
Testing the GT3 RS 3.8, 4.0 and 4.1 back to back over a couple days last year three of three test drivers preferred iron.
At the Spyder launch I asked the project lead- he personally feels PCCBs are over-assisted, prefers the feel of iron and said he couldn't feel the dynamic difference of PCCBs.
WR suggested the iron on the GT4.
I own both and have driven both extensively.
It comes down to personal preference, and Porsche knows its customers. Most prefer the lighter pedal- if they didn't Porsche wouldn't go that direction. However it's clear that the more motorsports focused the use the more higher effort is preferred, and it's also clear that Porsche is going against its engineering instincts with regards to pedal effort in order to please customers- they have said as much.
There's no question both brakes are great. There is also no question that opinions on feel vary, or that motorsports brake pedal forces are in fact massively higher.
It terms of feel I suspect preferences differ in part depending on personal experience and what direction you're coming from. A few data points, however:
Testing the GT3 RS 3.8, 4.0 and 4.1 back to back over a couple days last year three of three test drivers preferred iron.
At the Spyder launch I asked the project lead- he personally feels PCCBs are over-assisted, prefers the feel of iron and said he couldn't feel the dynamic difference of PCCBs.
WR suggested the iron on the GT4.
I own both and have driven both extensively.
It comes down to personal preference, and Porsche knows its customers. Most prefer the lighter pedal- if they didn't Porsche wouldn't go that direction. However it's clear that the more motorsports focused the use the more higher effort is preferred, and it's also clear that Porsche is going against its engineering instincts with regards to pedal effort in order to please customers- they have said as much.
Pete, do you think the PCCB "over-assist" is unique to 991/981 series cars? I am certainly no expert, but I have not "felt" an over-assist on my cars with PCCB versus the required/felt effort on my non-PCCB cars (997.1 C2S, 997.2 C2S, 997.2 GT3). My only 997.2 PCCB experience was with my 2011 Turbo S, but I have PCCB's on my 2014 Turbo S, 2014 GT3, and 2016 GT4. My incoming 2016 Boxster Spyder will not have PCCB's, so I will be interested to see how they feel to me.
Brakes are like suspension. Car owners often feel that more grabby/sensitive/lighter brakes equate to better braking, much like how many often argue their cars handle better just because of stiffer suspension setup when no there is improvement in lap times.
There are multiple BMW owners who argue their cars have superior brakes from the factory due to large discs and lighter brakes compared to Porsches. It's a huge perception. Not saying PCCBs over assist, but it's just that they require less pedal effort.
Pete, do you think the PCCB "over-assist" is unique to 991/981 series cars? I am certainly no expert, but I have not "felt" an over-assist on my cars with PCCB versus the required/felt effort on my non-PCCB cars (997.1 C2S, 997.2 C2S, 997.2 GT3). My only 997.2 PCCB experience was with my 2011 Turbo S, but I have PCCB's on my 2014 Turbo S, 2014 GT3, and 2016 GT4. My incoming 2016 Boxster Spyder will not have PCCB's, so I will be interested to see how they feel to me.
I believe the pedal effort has been lower in PCCBs since inception, but it does change from model to model with variations in master cylinder and brake size. To my taste the 987 and 997 GT cars were both over- assisted for both the street and track. I'd go for a slightly firmer pedal than even the iron as an ideal to split the difference, more like what Porsche ran back in the "big red" era.
As an aside, engineers also mentioned recent pedal feel has been effected by CO2 emissions targets: today's calipers must have less drag on the rotor to improve mileage, meaning a bigger dead zone before braking starts. Some changes to assistance were required to make this less noticable.
I believe the pedal effort has been lower in PCCBs since inception, but it does change from model to model with variations in master cylinder and brake size. To my taste the 987 and 997 GT cars were both over- assisted for both the street and track. I'd go for a slightly firmer pedal than even the iron as an ideal to split the difference, more like what Porsche ran back in the "big red" era.
As an aside, engineers also mentioned recent pedal feel has been effected by CO2 emissions targets: today's calipers must have less drag on the rotor to improve mileage, meaning a bigger dead zone before braking starts. Some changes to assistance were required to make this less noticable.
Thanks, Pete. i have always thought that I also preferred a firmer pedal as well. Apparently, I am easily recalibrated.
10-07-2015 | 09:11 PM
