Carbon Brakes - walk away or worth it?

Carbon Brakes - walk away or worth it?

Author
Discussion

mrdemon

21,146 posts

264 months

Tuesday 15th July 2014
quotequote all
as I have been swapping pads and doing brakes tests with the vbox, which I might add backs up every thing I have said on here.

here is a pic of just how big the front pads are from a oem 4pot car to the 6 pot PCCB car.


as I said the vbox shows a night and day performance advantage from the oem to PCCB set up, but so did swapping out to RS29 pads over oem on the 4 pot set up, but could still not match the PCCB set up.

Steve Rance

5,435 posts

230 months

Tuesday 15th July 2014
quotequote all
mrdemon said:
as I have been swapping pads and doing brakes tests with the vbox, which I might add backs up every thing I have said on here.

here is a pic of just how big the front pads are from a oem 4pot car to the 6 pot PCCB car.


as I said the vbox shows a night and day performance advantage from the oem to PCCB set up, but so did swapping out to RS29 pads over oem on the 4 pot set up, but could still not match the PCCB set up.
I think that the ceramic discs are a bit of a red herring here. The increase in stopping power is down to the caliper. They fit those 4 pots to the front as standard???

GreatPretender

26,140 posts

213 months

Tuesday 15th July 2014
quotequote all
Steve Rance said:
I think that the ceramic discs are a bit of a red herring here. The increase in stopping power is down to the caliper.
Hallelujah!

mrdemon

21,146 posts

264 months

Tuesday 15th July 2014
quotequote all
one of my quotes in this thread , which still got poo pooed

"forget the carbon disks,, the Calipers are massive 6 pots with 350mm size disks, vs 4 pots with 330mm disks."

that was on page 2 of this 10 page ramble ;-)


rosino

1,346 posts

171 months

Tuesday 15th July 2014
quotequote all
mrdemon said:
one of my quotes in this thread , which still got poo pooed

"forget the carbon disks,, the Calipers are massive 6 pots with 350mm size disks, vs 4 pots with 330mm disks."

that was on page 2 of this 10 page ramble ;-)
I think you just convinced me to go back to Steel on my 991 order then.. 6pots 380mm front and 4pots 380mm back... I believe should be more than enough. Save myself 6k to start with and a MASSIVE headache if I ever wanted to use the car as intended (i.e. sneak in a Spa session) and the brakes were to get used and need replacing.

With these extended warranty they have basically closed the door to competition re parts replacement. Otherwise there would be quite a few alternatives to OEM CCB discs to make it more viable in the long term.

Adam B

27,142 posts

253 months

Tuesday 15th July 2014
quotequote all
rosino said:
mrdemon said:
one of my quotes in this thread , which still got poo pooed

"forget the carbon disks,, the Calipers are massive 6 pots with 350mm size disks, vs 4 pots with 330mm disks."

that was on page 2 of this 10 page ramble ;-)
I think you just convinced me to go back to Steel on my 991 order then.. 6pots 380mm front and 4pots 380mm back... I believe should be more than enough. Save myself 6k to start with and a MASSIVE headache if I ever wanted to use the car as intended (i.e. sneak in a Spa session) and the brakes were to get used and need replacing.
rofl maybe mrdemon will finaly drop this as he seems to be encouraging everyone the wrong way smile

mrdemon

21,146 posts

264 months

Wednesday 16th July 2014
quotequote all
it's the right way on a Cayman or a Boxster as the oem 4 pots are just too tiny and the brakes are not that great.

If the car had 6 pot calipers as standard than yes don't bother, but 2nd hand you pay no extra to have PCCB and you can buy after market steel disks in the larger size no problem.

hence why I said on the GT4 it has to have 6 pots standard as speccing PCCB at 5k just to get good brakes on a car like the GT4 is going to be expensive.

The OP was looking at a Boxster and my talks have always been about Caymans and Boxsters :-)

ORD

18,086 posts

126 months

Thursday 17th July 2014
quotequote all
mrdemon said:
it's the right way on a Cayman or a Boxster as the oem 4 pots are just too tiny and the brakes are not that great.

If the car had 6 pot calipers as standard than yes don't bother, but 2nd hand you pay no extra to have PCCB and you can buy after market steel disks in the larger size no problem.

hence why I said on the GT4 it has to have 6 pots standard as speccing PCCB at 5k just to get good brakes on a car like the GT4 is going to be expensive.

The OP was looking at a Boxster and my talks have always been about Caymans and Boxsters :-)
You should qualify this by saying "not that great" for track driving. If you need more braking force on the disks (rather than grip from the tyres under braking) on the road, your driving licence is in serious danger! I have tried to find a point at which (at legal speeds) the tyres are not the limiting factor in braking, and I just don't think it is there.

(To be fair, though, I think fade is probably a relevant consideration, as I expect you could make the 4 pots fade badly if you chose the right B road and braked enthusiastically for every corner.)

mrdemon

21,146 posts

264 months

Thursday 17th July 2014
quotequote all
lets not kid each other on how fast people drive these cars.
the oem set up has no bite and really makes you lack confidence.

yes I have just re-bled the brakes twice in a row and fitted RS29's all round , it is far better and nice bite and less pedal travel now.

people seem to be having big issues with brakes and feel on the 987.2 cars and the bleeding system, I had air in mine (Porsche not long ago did my brakes at service time)

I bled them in full, went for a run out, -bled them again and air was in them again on the front left calpier.

they are now quite hard, but drive 80% of 987.2 cars and you have massive pedal travel and no bite.

very odd why the 987.2 cars seem to be having this issue over the 987.1 cars and is well reported.

rosino

1,346 posts

171 months

Thursday 17th July 2014
quotequote all
Just an idea.. and a bit off topic at that too... But if the car comes with decent sized brakes already.. i.e. the 991 GT3 with 380mm all round, 6 pots front, 4 rear.

Wouldnt it be a possibility to instead of paying the Porsche price go aftermarket directly and buy carbon brakes from Alcon or Surface Transforms ? They should be similar price than the factory Porsche option.. last longer and you can replace rotors only if you burn them at a FRACTION of the price of Porsche's (MOVIT Cer also an alternative but I think twice the price).

ALSO.. down the road when the factory warranty expires if you want to extend it you can fit back the std steels and then the car will be factory again and warrantable. If you burn your "official" PCCB once. you can kiss goodbye to your warranty unless you are ready to shell out best part of 20k GBP to buy their overpriced replacement system..

Just a thought no ?

fioran0

2,410 posts

171 months

Tuesday 29th July 2014
quotequote all
mrdemon said:
as I have been swapping pads and doing brakes tests with the vbox, which I might add backs up every thing I have said on here.

here is a pic of just how big the front pads are from a oem 4pot car to the 6 pot PCCB car.


as I said the vbox shows a night and day performance advantage from the oem to PCCB set up, but so did swapping out to RS29 pads over oem on the 4 pot set up, but could still not match the PCCB set up.
Hmmm, I am sure it does.

For accuracy.... you haven't don't one of your switcheroos here and are now pretending that you were talking about something else all along? We are still talking about stopping distance right? Stopping distance that is entirely governed by the tyre/road interaction?

In response to your brake pads, the size of brake pads have no impact on the braking power (or more accurately torque) a car has. The pads are external to the braking system hydraulics and so the clamping force produced by the system is unchanged by pad size or shape. The brake system produces a certain amount of force which is applied TO THE PAD. Since Force = pressure x area, a larger pad experiences a lower pressure per sq in when compared to a smaller pad for the same applied force.

Total braking torque is a product of 4 things. Caliper piston area, Line pressure, Brake friction coefficient and Effective radius.
Don't ever just assume that more pistons equal more piston area either. Mk1 GT3 4 pots have more piston area than Mk2 GT3 6 pots for example.

There are benefits from a larger pad, the ability to stop in a shorter distance (the discussion here) or an increase in brake torque are not them.


Edited by fioran0 on Tuesday 29th July 02:58

mrdemon

21,146 posts

264 months

Tuesday 29th July 2014
quotequote all
you won't be agreeing with Steve Rance either then :-)

"The increase in stopping power is down to the caliper"


but only one reason to bring back a 2 week old thread at 2am !!!!


Edited by mrdemon on Tuesday 29th July 09:33

fioran0

2,410 posts

171 months

Tuesday 29th July 2014
quotequote all
mrdemon said:
you won't be agreeing with Steve Rance either then :-)

"The increase in stopping power is down to the caliper"


but only one reason to bring back a 2 week old thread at 2am !!!!


Edited by mrdemon on Tuesday 29th July 09:33
Because this was the first time that I saw it, having been away abroad and not online and am still at present not in the UK timezone?

If you look at the line about what factors influence total brake torque you will see them already listed as i)piston area, ii)line pressure, iii)brake pad friction coefficient and iv)effective radius.
This is NOT at odds with Steves post which I assume was also suggesting that any differences (if present) in brake torque between systems would be as a result of changes to these 4 factors.

Note that brake pad size is not featured in this list. Explanation of why is above. Caliper does not mean brake pad.

This is still a sidebar to the stopping distance discussion though for two reasons.

1) You can only decelerate as quickly as the tyre will allow and no more. Put whatever brake system component upgrades on there you like and you cannot reduce your stopping distance one bit as it doesn't change this tyre/road interface and thus rate of deceleration.

2) ABS caps the brake system performance. Modern ABS runs pre-emptive and reactive strategies. It is making changes and adjustments almost continuously throughout most braking events. If one is sceptical, run brake line pressure sensors to a data logger and watch the ABS manipulating braking in subtle and not so subtle ways. It is active long before the "crap we are going to crash" intervention. This is a second reason why upgrading brake components does not reduce stopping distance. What you gain from the changes, the ABS generally removes by changing line pressure. This is also the explanation for why putting slicks onto a road car does not improve stopping distance despite point 1 and explains why you are not bombed under braking by road cars on slicks at an average track day.

I have never once claimed that there are not advantages and disadvantages from PCCB just as I have never claimed that there are advantages and disadvantages from larger brakes in general. This multipage carousel continues in response ONLY to the suggestion that one can stop in a significantly shorter distance.



Edited by fioran0 on Tuesday 29th July 11:14

SHIFTY

888 posts

235 months

Tuesday 29th July 2014
quotequote all
Advantage to me the CCB pistons fill the 20" wheels better, minimal brake dust, feel better when braking.

Disadvantage CCB used up the entire discount I managed to obtain when buying the car.

ORD

18,086 posts

126 months

Tuesday 29th July 2014
quotequote all
SHIFTY said:
Advantage to me the CCB pistons fill the 20" wheels better, minimal brake dust, feel better when braking.

Disadvantage CCB used up the entire discount I managed to obtain when buying the car.
The brake dust thing isn't a small consideration, in my view... not if you clean your own car or pay someone else to do it properly. I could easily spend thousands of pounds a year of my own time or paying someone else to clean my damn wheels!

V8KSN

4,711 posts

183 months

Tuesday 29th July 2014
quotequote all
Just read this thread from top to tail, some very interesting posts on here, thanks guys.


mrdemon

21,146 posts

264 months

Tuesday 29th July 2014
quotequote all
fioran0 said:
1) You can only decelerate as quickly as the tyre will allow and no more. Put whatever brake system component upgrades on there you like and you cannot reduce your stopping distance one bit as it doesn't change this tyre/road interface and thus rate of deceleration.
I have proven that wrong already fitting RS29 pads on the same car made the distance to stop shorter.

AS I have said before you cannot lock a wheel at 120mph, so more friction/bite etc will stop the car shorter on the same tyres at those speeds.
fit caliper spacers and 350mm disks over 330mm disks you would see the car stop shorter again.

edo

16,699 posts

264 months

Tuesday 29th July 2014
quotequote all
Just cleaned the 981 after 500 miles, 80 of which were on Bedford Autodrome.

No wheel cleaner, and a white cloth was barley grey after doing all 4 wheels. Not per say worth the 5k asking price, but an hour less cleaning the wheels once a week adds up if you value your time!

Not to mention they performed faultlessly and allowed me to stay out long enough for the MP124C behind (without ceramics) to have to give up with overheated brakes hehe

fioran0

2,410 posts

171 months

Tuesday 29th July 2014
quotequote all
This just in.....
Exclusive spy photo of recent testing. "You Reeker!" shouts pioneer, "Peep peep" says assistant.


mrdemon

21,146 posts

264 months

Wednesday 30th July 2014
quotequote all
See what Alcon say

" As a result of our unique design, CCX delivers exceptional initial bite, even when cold. Shorter stopping distances and increased stability under braking improves road safety, makes CCX
the ultimate brake whether you are on the road or on the track."

Mmmm shorter stopping distances :-)