PCCB out braked the steels last night on 5th gear.

PCCB out braked the steels last night on 5th gear.

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APOLO1

4,644 posts

142 months

Monday 18th November
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Spyder75 said:
I asked Manthey about PCCB wear and they said they haven’t replaced a set of discs yet (since 2016) except a guy who ran the pads to the backing plates. Apex are expecting 30k ring kms on their gt2 rs.

They also use a different pad which helps disc wear. I don’t recall the exact conversation but I think the gist was the material doesn’t smear like OEM and as a result less heat builds up.

It was at this point I stopped worrying about PCCB wear and am enjoying them for what they are. Phenomenal stopping power and I’m sure a massive contributing factor on how the car drives especially on our terrible road surfaces.
Not in the least bit surprised about this based on my own experience with the Post Aug 13 PCCBs. Post this time the PCCBs across the VAG range were manufactured using a different process, also with the addition of a ceramic coating. Provided the pads are not run down to the wire they will last a very long time. I did over 40 Track and V-Max events in my 91RS around 10k track Miles, I had to replace 2 Discs due to stone chips not wear in order to keep in the 111 Inspection guide lines. Personally I much prefer the use of PCCBs on road and track.

Porsche911R

Original Poster:

17,879 posts

213 months

Monday 18th November
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So it looks like the 5th gear test was pretty black and white and the people who track PCCB cars agree as does Manthey.

about time the dinosaurs got on board ;-) esp as disks have got bigger over time the weight saving has increased also by quite a large margin, bringing along the others advantages that brings.

Also as people have stated try and get a price on the GT3 380mm and then try the trick ones from Brembo, these prices have also sky rocketed, making the £6k option for the disks VERY cheap.

I am a convert from 2010 and saw the real world difference, I speced my GT4 wrong, but I did that with a few things on that car inc those gasty 918 seats... the car was new, the seats were new,the brakes were big. I went with it. So while some quote me on that I corrected my errors in my GT3 which has PCCB's and folding buckets :-)

3 of my current cars run ceramic disks they are better in every single way vs the non cost option in all 3 of my cars and over different brands.

wheels is the next big test, the Mags are bringing in a big advantage, if you don't have PCCB's and Mag wheels on these new £200k super cars you are not getting the best from them...and the key thing is they are CHEAP to option over buying after on both accounts.

people have been asking for PCCB tests for years, we now have had one, get with it people :-)

isaldiri

5,029 posts

116 months

Monday 18th November
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Porsche911R said:
people have been asking for PCCB tests for years, we now have had one, get with it people :-)
Actually this is the 3rd that I can remember and the first time it has shown an advantage for ceramics. Funnily enough you choose to ignore the earlier c&d and evo tests that show roughly equal performance.

Dammit

3,227 posts

156 months

Monday 18th November
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Possibly because 911R is the concept of confirmation bias made into a man.

Twinfan

4,182 posts

52 months

Monday 18th November
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Due to the not inconsiderable difference in caliper and disc spec between steels and carbons on a 718T, I'd like to see a proper test on a GT car performed to see what the differences are there as you cannot extrapolate the data to other sports cars in the Porsche hierarchy from this single test.

Porsche911R

Original Poster:

17,879 posts

213 months

Monday 18th November
quotequote all
isaldiri said:
Actually this is the 3rd that I can remember and the first time it has shown an advantage for ceramics. Funnily enough you choose to ignore the earlier c&d and evo tests that show roughly equal performance.
tech and the size has moved on, As I stated above being bigger the weight difference is now much greater also.
This is a current test on current like for like cars at REAL SPEEDS it was a pretty big win.

I think past tests were done at LOWER speeds which then is a tyre/grip issue.

you CANNOT over come tyre grip at >80mph, you can at 60mph so it shows what the brakes are doing over what the tyres are doing.

Take this out to 120mph and you will see even a bigger gap in performance.

Maybe that's why Porsche told them to use 80mph to show the difference.

APOLO1

4,644 posts

142 months

Monday 18th November
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isaldiri said:
Actually this is the 3rd that I can remember and the first time it has shown an advantage for ceramics. Funnily enough you choose to ignore the earlier c&d and evo tests that show roughly equal performance.
Happy to be corrected, but did the 997.40 RS with PCCBs hold the record for braking distances for a very long time.? with regard to a Production car.

In my opinion a lot of the fear factor around PCCBs is down to the ones fitted on pre Aug 13 cars. I agree whist there was nothing wrong with these for road use or as above stopping distances/performance, but they did not last anything like the ones on the Post Aug 13 cars that have the ceramic coating when used for hard track use.

My own experience with OEM steels on track is that whist that they remain OK for a few fast laps after a short time of hard use they do go off and braking distances start to increase, whist cars fitted with the post Aug 13 PCCBs remain constant for the whole day, provided cooling laps are done. If not then its the Pads that suffer the heat soak along with the brake fluid gets to hot.

Sure you recall the time in 991 Turbo S, when it went red flag after some very fast laps and we had to come in with no chance to do a cool down lap.

Edited by APOLO1 on Monday 18th November 09:40

isaldiri

5,029 posts

116 months

Monday 18th November
quotequote all
Porsche911R said:
tech and the size has moved on, As I stated above being bigger the weight difference is now much greater also.
This is a current test on current like for like cars at REAL SPEEDS it was a pretty big win.

I think past tests were done at LOWER speeds which then is a tyre/grip issue.

you CANNOT over come tyre grip at >80mph, you can at 60mph so it shows what the brakes are doing over what the tyres are doing.

Take this out to 120mph and you will see even a bigger gap in performance.

Maybe that's why Porsche told them to use 80mph to show the difference.
laugh

Think again then. Evo and c&d tests were 100mph stops so higher than 80 of the supposed one true definitive 5th gear test.

For a more direct comparison with a car with more competent brakes on both materials, SportAuto braking tests for a iron 991 c2s compared to a ceramic gts back in 2015/2014 (different days) with both on exactly the same tyre actually showed an advantage in both 100 and 200 km/h braking tests. No one with half a brain is claiming that definitively shows the steel brake car 'wins' though...

isaldiri

5,029 posts

116 months

Monday 18th November
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APOLO1 said:
Happy to be corrected, but did the 997.40 RS with PCCBs hold the record for braking distances for a very long time.? with regard to a Production car.
Yeah I think so but that was because Porsche didn't bother to send one with steel brakes instead at the time... :P

The fear factor though is simply due to the extraordinary cost of replacement. Not relevant if the car is a new car to be turned around for something else in at most 2 years unless one is seriously hammering a car on track every other week which other than you hardly anyone does wink but for a subsequent long term owner, imo that cost of replacement, no matter how much more lasting the ceramics are now (and I agree they do last a lot better) is an issue.

Edited by isaldiri on Monday 18th November 10:04

Porsche911R

Original Poster:

17,879 posts

213 months

Monday 18th November
quotequote all
isaldiri said:
For a more direct comparison with a car with more competent brakes on both materials, SportAuto braking tests for a iron 991 c2s compared to a ceramic gts back in 2015/2014 (different days)
so different cars !!! on different days !! prob on different bits are tarmac , FFS totally pointless....

GTS weigh more for a start !

weight is every thing when braking as are grip levels on the day.


Oilchange

5,807 posts

208 months

Monday 18th November
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The only way to get an accurate idea of the advantages of steel against PCCB is to stick equivalent size stuff on two identical rigs and blast the crap out of them, then analyse the data. Otherwise there will be too many factors influencing the results, tyres, tarmac, car weight etc etc etc etc etc etc


isaldiri

5,029 posts

116 months

Monday 18th November
quotequote all
Porsche911R said:
so different cars !!! on different days !! prob on different bits are tarmac , FFS totally pointless....

GTS weigh more for a start !

weight is every thing when braking as are grip levels on the day.
Actually weight is not everything as long as the braking system can cope with the amount of heat it is required to absorb.

And it is a comparison of cars with more closely matched brakes. A decent sized iron rotor/caliper vs the ceramic one. That is less pointless than you grasping at a single test at a lower speed as the definitive proof ceramics have an advantage and ignoring 2 other ones that have tested the exact same cars.

It is simply a question of what one wants to ask. I don't disagree that in some cases, like perhaps here on the 718 T the ceramic brake option will brake better as it has more capability in the braking system. What I do dispute is that ceramics are always going to brake better than steels. On a GT car that is not the case.

Steve Rance

4,997 posts

179 months

Monday 18th November
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Porsche911R said:
surprised no ones talked about this yet.

as the normal suspects poo poo PCCB and say no advantage.

5th gear, 2 cars, same model,tyres etc , The PCCB car killed the steel shod car by a nice margin (16 feet) then after 10 stops beat it by 100 feet.

black and white PCCB win really.

Edited by Porsche911R on Friday 15th November 15:20
Yep, definatelty back on the old tablets..

hunter 66

2,874 posts

168 months

Monday 18th November
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On track days the tyres go off first by a significant amount after 4-5 laps . On slicks this is reduced and in an hour and 15 mins stint , not noticed any fade on Steel brakes over a 24 hour race period . Yes the car is a few hundred kg lighter but then also being driven much harder .
Anyway meaningless as more than enough in both situations , so more question of personal preference . Most in Europe prefer steel brakes , whereas here in the UK prefer carbon .

Porsche911R

Original Poster:

17,879 posts

213 months

Monday 18th November
quotequote all
Steve Rance said:
Porsche911R said:
surprised no ones talked about this yet.

as the normal suspects poo poo PCCB and say no advantage.

5th gear, 2 cars, same model,tyres etc , The PCCB car killed the steel shod car by a nice margin (16 feet) then after 10 stops beat it by 100 feet.

black and white PCCB win really.
Yep, definatelty back on the old tablets..
I did not write or do the test !, The die hards seem are the non PCCB fans for some reason !

Yellow491

1,417 posts

67 months

Monday 18th November
quotequote all
Porsche911R said:
Steve Rance said:
Porsche911R said:
surprised no ones talked about this yet.

as the normal suspects poo poo PCCB and say no advantage.

5th gear, 2 cars, same model,tyres etc , The PCCB car killed the steel shod car by a nice margin (16 feet) then after 10 stops beat it by 100 feet.

black and white PCCB win really.
Yep, definatelty back on the old tablets..
I did not write or do the test !, The die hards seem are the non PCCB fans for some reason !
R you seem hell bent on any journo or bias film as gospel.
Ceramics are a big marketing exercise,that you have swallowed.
People refering to carbon is very different to ceramics,the only real advantage i see ,is less brake dust to need to clean the wheeels less.
Majority of race cars use steels,more reliable and longevity for the performance given,alot of race teams would not worry about costs of ceramics if they offered a real return in performance advantage,so how does this even come into the equasion on a road car.

Answer a question R,if the weight saving is that critical to performance of a road car on road tyres,why are the dampers and spring rating not any different of steel over ceramic on the gt cars,and for that matter mag wheels.

ab8

153 posts

88 months

Monday 18th November
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I commend to everyone Petevb's post on Rennlist, from 2015 (https://rennlist.com/forums/gt4/875965-actual-real-weight-savings-with-pccb-s-2.html#post12319468), which I've copied and pasted below for convenience. I don't know if it's right, but with my distant A-Level physics it seems sensible.



"It is quite surprising the way it works out. In terms of moment of inertia, which changes turn-in, acceleration, etc, the position of the mass matters more than the quantity, which leads to some surprising results when you look at the wheel and tire package as a system:

First realize that rubber is surprisingly heavy, and it's located way out at the edge of the wheel. Shaving 1/8" of rubber works out to roughly 4 lbs on our width tires, but since it's out at the edge of the wheel as opposed to close to the center, this difference has an outsized effect on moment of inertia (MOI). That 4 lbs is roughly equal, in fact, to the MOI of the entire 14.8 lb PCCB brake disk, meaning it's just as hard to accelerate, turn, etc.

This has a different effect than simple unsprung weight which effects ride, of course, but the flywheel effect on turn-in is often described as being the most noticeable difference for PCCBs- the ease with which the wheel turns.

In terms of this the iron rotors do have a 37% higher MOI than PCCB, but that's only equivalent to roughly 1 mm more tread rubber- not exactly a big difference when viewed this way.

If we then simply focus on "unsprung weight" the difference is also much smaller than first appears. One must keep in mind that the iron rotors lose nearly 2.5 lbs before they hit the wear limit, while PCCBs do not lose nearly as much. Thus looking at the front, worn iron rotors and pads with a shaved tire will cut the absolute weight difference to PCCBs to zero (4 lbs of shaved rubber, 2.5 lbs of lost rotor mass, 1.5 lbs for worn pads, while the calipers and pads were 1 lb lighter to begin with = 9 lbs, where the stock PCCB rotor is ~9 lbs lighter to begin with). This setup will also have a nearly 40% lower moment of inertia than the PCCB setup with fresh rubber, so in virtually every way could be expected to perform better.

I don't find it impossible to believe that some people could tell the difference with PCCBs, and in absolute terms they should be fractionally faster when all else is equal. The difference you're trying to feel, however, is in most ways smaller than fresh vs shaved rubber, particularly with worn vs new rotors and pads. In other words it's really quite small, and in the real world dwarfed for me by other effects such as brake feel, etc.

Throw in the added front downforce the iron rotor generates on the GT4 and I do start to wonder which car would be ultimate faster on fast tracks over a single lap, a worn iron rotor car or a PCCB car...

Where the PCCBs still retain a big advantage is in absolute braking capacity. A 918 equipped with the GT4's iron rotors could dump enough power into them to overheat and fade them. The PCCBs on the other hand have more surface area to shed heat, as well as a higher allowable peak operating temperature. This means you can push them harder before they give up. The GT4, however, has less than half the 918's engine power- likely not enough to practically be able to overheat the standard metal disks. They are after all the same dimensions as you'll find on many cars at Le Mans, so in this instance the PCCB's thermal advantage is somewhat academic. On a 918 however it's clearly not.

Food for thought as you decide how to spend your $$."

isaldiri

5,029 posts

116 months

Monday 18th November
quotequote all
It'll never register but it's not a matter of being a die hard or a fan of any bloody braking material. It's simply a question of taking things in the correct context and not spouting gibberish then claim it's the gospel truth.....

The Surveyor

6,946 posts

185 months

Monday 18th November
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JulierPass said:
Porsche911R said:
JulierPass said:
I haven't seen the article as I don't watch 5th gear. However, there is a reason why all of the factory built Porsche Cup Cars and R's have steel brakes. If the advantage was as pronounced as your post suggests then the race would come with ceramics from the factory.
Higher up the racing tree they do use carbon disks.
Yes, but that is more about weight in those series. My point is the factory built race cars, on which these roads cars are based do not have have ceramic brakes. If ceramics offered the retardation advantage that the average joe is lead to believe they have Porsche would fit them to their cup cars. I own and race one and have dealings with the factory so can be fairly catergoric in that statement.
Factory built race cars have to comply with the specific formula, Le Mans GTE class cars (for example) are not allowed to run ceramic discs, they have to run steel (iron) disks. It has less to do with weight or performance, it's written into the rules of the formula.

franki68

7,036 posts

169 months

Monday 18th November
quotequote all
I prefer ceramics ,but never specced them on a new Porsche just because I have always found the Steels excellent.
But back to the main point,surely it doesn’t really matter if steels match ceramics if the size is the same as you cannot buy a Porsche with steels that are the same size as the pccbs (I believe) .You can of course replace the standard steels but how many people do that ?