Spook's GT3 arrives!

[fireblade]

ORIGINAL: Lancerlot

ORIGINAL: fireblade

I wasn't that keen to have Ceramic brakes though as I have heard that these have to be changed out at intervals but the S does not give you a choice.
Michael

Yes having to check them at around 100,000 miles is a bit of an imposition, [8|] but once you've had them, you'll be reluctant to return to steel rotors and with 410mm diameter at the front, stopping shouldn't become a problem - even at 80 mph! []

Regards,

Clive.

Thanks Clive,


You have made me feel much better.

All the early ceramics here had problems with cracks some only lasting 3,000 miles. When ceramic's became standard on GT3,s local owners laughed as steel rotors
corroded here very quickly due apparently to our "salt air" particularly on cars (like track GT3,s) that weren't used much. After a few thousand miles they were not laughing and
were trying to retrofit steels!!

Good news to hear that they now last 100,000 miles as I drove a Ceramic equipped 997 Turbo on our last track day and it certainly outperformed my steels by a large margin.

Cheers Michael

 

[tscaptain]

ORIGINAL: fireblade

Good news to hear that they now last 100,000 miles as I drove a Ceramic equipped 997 Turbo on our last track day and it certainly outperformed my steels by a large margin.

In what sense, Michael?

 

[fireblade]

ORIGINAL: tscaptain

ORIGINAL: fireblade

Good news to hear that they now last 100,000 miles as I drove a Ceramic equipped 997 Turbo on our last track day and it certainly outperformed my steels by a large margin.

In what sense, Michael?

Quicker response to equal pedal pressure and without any hint of lockup, tremendous stopping power nearly throwing me at the steering wheel. Might have been a bit psychological
because I was encouraged to brake later and possibly unknowingly harder. No trace of fade either which I have experienced with the steels on shorter tracks where braking is more frequent.

Everyday use no idea of difference..... so far!



Cheers

Michael

 

[tscaptain]

The last point I can get but the others...? I think the stopping force is limited by the tyres/ABS/grip levels by both types of disc so you are probably right in that it is psychological! Also someone elses car.......[] When I was deliberating over the spec on mine the instructor at Silverstone was of the opinion that both will stop in the same distance and that the longevity and non-fade properties of the PCCB were the only difference (apart from the cost!) One thing is for certain - when it comes to stopping a modern Porsche takes some beating.[]

 

[Lancerlot]

That instructor clearly didn't appreciate what a banzi driver and last of the late brakers you are Alan or he would have obviously advised you quite differently, I'm sure! []

PCCB's offer improved performance and a reduction in unsprung weight, so are better all round. You're the only driver I know who doesn't agree.

With either setup one needs to keep an eye on the rear pads ahead of normal service intervals however, as with PTV these tend to wear at a greater rate than usual. []

Regards,

Clive

 

[tscaptain]

That's not what I'm saying.[] I would agree that if the same car weighs slightly less then it will stop in a shorter distance (physics). However if you and I were doing the same speed and both hit the brakes as hard as we can the ABS will intervene in both cars - no? If that is the case then the stopping distance, given same tyres, will be the same, to all intents and purposes. Clearly the PCCBs have other advantages but I don't see that stopping in less distance is one of them. However, that said, I don't think the steels with OEM pads are that inspiring at initial brake application. They improve somewhat with a pad upgrade.[]

 

[Lancerlot]

Oh dear, I can't really agree there either, Alan. Sorry about this.[8|]

Steel rotors are 380mm all round, whilst PCCB's are 410mm front, 390mm rear, therefore stropping distance is greatly improved. It's a no brainer really. []

Regards,

Clive.

 

[fireblade]

I agree with you Alan particularly about the ABS coming in to compensate for heavy feet.

The actual physics from Clive are all spot on but at the level of tracking that I do it would probably be difficult to measure the difference particularly as I really do not push my car.

I take your point about using someone else's! I recall that the ceramic car had Pirelli's whilst mine runs on Bridgestone which may not be as good as the PZero but they have
lasted over twice as long mileage wise. No idea what the new car will arrive with but the S already here is on Pirelli's and while the fronts have a nice rim protecting"overhang" that I like
(so I recall does Gary), the rears are just about flush and the rim and look very susceptible to kerb damage particularly with the wider rear.

However the instructor (local independent Porsche technician and owner but not 911) drove the ceramics first then mine and said that he nearly ran out of road on the straight as mine just
did not have the same stopping power.

I am looking forward to the tracks I know well when the new car arrives so I will have a yardstick to judge by.

I will certainly give you my layman impressions thereafter.

Cheers

Michael

 

[ralphmusic]

For what it is worth, the GTS had 330mm front disks and I was on my 4th set, albeit with track day use, because they are undersized for a 1630kg 400+ bhp car that could get up to 140mph before braking for Woodcote at Goodwood. However I never experienced any brake fade (possibly brain fade). Most of the fellows with GT3's seemed to have steel disks and those with ceramics took special care to warm up and warm down on each run.

 

[tscaptain]

Hmm.. well in the first instance I assumed Michael was comparing 997 turbo brakes where the disc sizes are the same on both steel and PCCB, as on yours and mine?

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.

Source :http://www.caranddriver.com/features/the-power-to-stop-performance-cars-page-4

I still maintain that you can have the largest brake rotors in existence but the contact patch with the road will be the limiting factor in the modern car where all other factors are equal. Feel, brake dust, wear, fade (although the article above suggests there is little real world difference) unsprung weight (and therefore handling), track use, appearance and longevity may well be better with PCCB but please explain how stopping distance is better.

 

[Lancerlot]

ORIGINAL: tscaptain

..........but please explain how stopping distance is better.

Brakes dissipate heat. They simply turn kinetic energy into heat.

You get more brake torque with larger diameter rotors. Larger brakes means less effort, a larger surface area for cooling, larger mass for heat capacity, more pistons and larger pads to distribute the forces and prevent friction surface temperature rising beyond optimum levels.

Smaller brakes dissipate heat less efficiently and when temperatures rise beyond the normal operating levels, braking distances are increased. Simples really! [8|]

Regards,

Clive

PS. Apologies to Peter for high-jacking his thread.

 

[tscaptain]

ORIGINAL: Lancerlot

PS. Apologies to Peter for high-jacking his thread.

Agreed![]

 

[pwebb]

All good educational stuff! Standard turbo brakes have always attracted positive comments from the press for their efficiency and my C2S has the same size as the 997TT IIRC. so with considerably less weight to stop, that makes me a happy bunny. I've never had ceramics so can't comment objectively anyway.

It would be interesting to see comparable tests with stopping distances for the various models, but am not aware that it has ever been done in a controlled way.

 

[Lancerlot]

Brakes for the 996 turbo with 400 BHP and Gen 1 997 turbo with 470 BHP were, I believe, the same with 350mm steel rotors, which proved woefully inadequate in the latter IMHO. The pressurised hydraulic system developed to preload the pads and reduce pedal travel actually had the opposite effect if you were left foot braking, as the pedal would go nearly to the floor before any retardation happened - not very confidence inspiring! The situation improved with the Gen. 2 turbo and 380mm rotors, although as Alan has indicated, you really need non-stock, updated pads to get the best from them.

Regards,

Clive.

 

[ralphmusic]

An interesting aspect of this subject is everyone talks of how wonderful Porsche brakes are, but a number of instances of under sized rotors, yet I have not heard of or experienced any inadequacies in performance, other than appetite for consumables, and BTW the 981 Cayman S has same sized rotors as the GTS - are the brakes always slightly behind the curve?

Clive, what do you make of the above?

 

[flat6]

Interesting discussion and I haven't put much thought into brakes other than PCCB are too expensive for me[]

Larger disc and pad surface area vs smaller
More pistons per caliper vs fewer
Same tyre contact patch

So on a basic brake distance test where you stamp on the brakes and the ABS kicks in, some of PCCB's greater stopping power is negated.

However, what about when you are trying to drive as fast as you can, which means braking as aggressively as you can but keeping the wheels rotating (locking up and bringing in the ABS makes you slower as both yourself and car's systems have to back off your progress). Wouldn't the PCCB's stronger stopping power be more superior then? Larger discs and pads and more pistons must bite harder for your foot's input? Yes if you stamp on them and lock up they're both equal when skating as that is the tyre not the brakes?

It's question rather than a statement. Will be interested to hear what actually goes on in aggressive braking.

 

[Lancerlot]

Ralph,

After a couple of OMG moments in my Gen 1 Turbo, my PC thoroughly checked and bled the system then reported back all was exactly as it should be. That's when I sold the car. [] My next 2 vehicles were both fitted with ceramic brakes as standard - that's when I became hooked. [8|]

After that, getting back into a Gen 2 Turbo with steel rotors was discomforting and I considered replacement pads, uprated hardware - even priced up a new PCCB replacement kit from Jersey (only 5% VAT). But in the end, it proved cheaper to replace the car. []

ORIGINAL: flat6

Interesting discussion and I haven't put much thought into brakes other than PCCB are too expensive for me[]

Larger disc and pad surface area vs smaller
More pistons per caliper vs fewer
Same tyre contact patch

So on a basic brake distance test where you stamp on the brakes and the ABS kicks in, some of PCCB's greater stopping power is negated.

However, what about when you are trying to drive as fast as you can, which means braking as aggressively as you can but keeping the wheels rotating (locking up and bringing in the ABS makes you slower as both yourself and car's systems have to back off your progress). Wouldn't the PCCB's stronger stopping power be more superior then? Larger discs and pads and more pistons must bite harder for your foot's input? Yes if you stamp on them and lock up they're both equal when skating as that is the tyre not the brakes?

It's question rather than a statement. Will be interested to hear what actually goes on in aggressive braking.

You're absolutely right. I was convinced after driving a Turbo 'S' on ceramics all day at Silverstone DEC (road and track) then returning home in my steel rotored Turbo. Ceramics offer better initial bite, more consistent pedal travel/stopping power and give greater confidence you're in control. Alan knows this really but won't admit it!

Of course, Ferrari no longer offer customers the option, all their cars now come with carbon ceramic brakes - and they know a thing or two about sports cars. [8D]

Regards,

Clive.

 

[Motorhead]

Clive,

Isn't the fact that, as you say, ceramics offer better initial bite a crucial point here? Under very hard brake application, will they not reach the ABS limit faster than their steel equivalent?

Jeff

 

[flat6]

But if you can scrub off your speed faster, you would leave your braking a little later as you can scrub off the same speed with a shorter duration prod of the brakes, not keep your foot in until lock-up?

I've now got a picture of PCCB's being so snatchy that there's lock-ups all the time and sore foreheads from hitting the windscreen[] but i'm guessing that more initial bite doesn't translate to locking[]

 

[ralphmusic]

So four 991 GT3 have now come up for sale, I guess typical speculators selling more than unhappy buyers?