Carbon Brakes - walk away or worth it?

[Porsche911R]

Kawasicki said:

Pistonheads is funny sometimes

Did not see this is a 2014 thread quote, but yes it is funny :-)

Hence why one learns threshold braking so when the wheels do start to lock at much slower speeds one can avoid abs cutting in.

so yep as you say it's funny ;-)

[Kawasicki]

Porsche911R said:

Kawasicki said:

Pistonheads is funny sometimes

Did not see this is a 2014 thread quote, but yes it is funny :-)

Hence why one learns threshold braking so when the wheels do start to lock at much slower speeds one can avoid abs cutting in.

so yep as you say it's funny ;-)

so you also think it is impossible to lock brakes at higher speeds?

[Porsche911R]

Kawasicki said:

so you also think it is impossible to lock brakes at higher speeds?

Depends on many things.
But don't try and find a look around.
When on track with good tyres you brake in a straight line, the inertia of the vehicle will reduce the potential to lock the wheels at the initial press of the brake pedal. You can therefore afford to work the brakes hard with big pedal effort. As the speed reduces, you need to consider reducing the pressure on the pedal.

Trail braking yes you might be able to lock an unloaded wheel.
How often do you even see an F1 car lock a wheel at the start of the braking zone ?
poor tyres, or rain etc etc yes ofcourse.

But when we talk about road cars and driving fast the 1st two things you learn about is brakes, and slip angles. It's basics learning that the wheels will not lock until a certain point and hence threshold braking is a key skill.

[bcr5784]

What is this all about - with ABS you don't/can't lock brakes!? Unlike stability controls, as far as I am aware you can't turn off ABS if you have it. If you want to exercise your braking skills get a Caterham!

[Kawasicki]

Porsche911R said:

Kawasicki said:

so you also think it is impossible to lock brakes at higher speeds?

Depends on many things.
But don't try and find a look around.
When on track with good tyres you brake in a straight line, the inertia of the vehicle will reduce the potential to lock the wheels at the initial press of the brake pedal. You can therefore afford to work the brakes hard with big pedal effort. As the speed reduces, you need to consider reducing the pressure on the pedal.

Trail braking yes you might be able to lock an unloaded wheel.
How often do you even see an F1 car lock a wheel at the start of the braking zone ?
poor tyres, or rain etc etc yes ofcourse.

But when we talk about road cars and driving fast the 1st two things you learn about is brakes, and slip angles. It's basics learning that the wheels will not lock until a certain point and hence threshold braking is a key skill.

...but I spent three days in Spain doing nothing but braking from 155+ mph, then fiddling with the abs controller to stop initial lock up. Are you sure?

Tell me more.

[Debaser]

Porsche911R said:

Depends on many things.
But don't try and find a look around.
When on track with good tyres you brake in a straight line, the inertia of the vehicle will reduce the potential to lock the wheels at the initial press of the brake pedal. You can therefore afford to work the brakes hard with big pedal effort. As the speed reduces, you need to consider reducing the pressure on the pedal.

Trail braking yes you might be able to lock an unloaded wheel.
How often do you even see an F1 car lock a wheel at the start of the braking zone ?
poor tyres, or rain etc etc yes ofcourse.

But when we talk about road cars and driving fast the 1st two things you learn about is brakes, and slip angles. It's basics learning that the wheels will not lock until a certain point and hence threshold braking is a key skill.

[Porsche911R]

Kawasicki said:

...but I spent three days in Spain doing nothing but braking from 155+ mph, then fiddling with the abs controller to stop initial lock up. Are you sure?

Tell me more.

you have a crap ABS system, or tyres :-), in your own words you changed the ABS setting to stop it kicking in, not your brake pressure !

[Porsche911R]

bcr5784 said:

What is this all about - with ABS you don't/can't lock brakes!? Unlike stability controls, as far as I am aware you can't turn off ABS if you have it. If you want to exercise your braking skills get a Caterham!

you can out brake an ABS system, and in a lot of cars you can get ice mode if ABS kicks in, hence threshold braking is key on track.

I am in wonder at what people drive like in here. In fact I am not as I have been in many cars on track days and people seem to lean on the ABS and other systems.

[Porsche911R]

Debaser said:

go on ?

[ab80]

Porsche911R said:

you can out brake an ABS system, and in a lot of cars you can get ice mode if ABS kicks in, hence threshold braking is key on track.

I am in wonder at what people drive like in here. In fact I am not as I have been in many cars on track days and people seem to lean on the ABS and other systems.

I have only read the last page of this thread so do not mean to engage in whatever controversy there is but...

I did a really interesting braking session with Colin Hoad experimenting with beating the ABS through properly controlled threshold braking and saw exactly this - you can beat the ABS. It's really quite rewarding.

[Neverbeen-too-fast]

interesting read why Ceramik breaks DO stop a car faster - although its pure physics - not mechanics - and the effect is small.

http://www.speed-werks.com/carbon-ceramic-brake-ro...

[Dr S]

Slippydiff said:

Anyone know where the "Whoosh parrot" emoticon is to be found ?

Which parallel universe do you live in when you think that two cooling down laps will stop PCCB discs from wearing out prematurely ?
I'd guess the same one that says don't put the handbrake on a 996/997 GT3 when you park up in the paddock after session on track .....

Just focus on what I wrote instead of making things up. Engineers tend to design braking systems fit for purpose. Please tell me in which world does a track exist where you could experience the type of braking scenario (including lack of cooling) that you suggest. I have not found one in my world but judging from the aggressiveness of your posts you must be certain to have found it in yours...

[Steve Rance]

Interesting reading this thread again. Also interesting that the ceramic V steels argument still rages on. No doubt that ceramic technology and certainly refurbishment technology has moved a long way during this time. My thoughts remain unchanged. Ill take a decent floating steel set up every time and put the - not insubstantial - cash saving elsewhere.

We run a 997 cup which has a steel floating set up on it as part of our company marketing statergy.10 or so customer days at Silverstone GP with 30-40 customer rides a day (normally 4 laps). The brakes get a lot of absue, there are some big stops at Silverstone, passengers are often well over 15 stone and we carry a heavy feul load for much of the day. Each ride is 10/10ths from the first corner of the ride to the last then straight into the pits, then belt another passenger in and straight out again. Thats all the cooling they get. No other cool down at all and no warm up. We stop at lunch time then run to the end of the day. Often there is thick smoke coming from the front pads while we are in the pits changing passengers. Occasionally they are acually on fire if there is pick up on them. They take a real hammering but function perfectly. No fade, no need to leak bias to the rear to maintain temps. No maintanance needed at all from the driver during the day... and they are good enough for a 50 meter braking point (dry) for Copse, lap after lap. I can rely on them all day. Never let me down.

Would I consider running ceramics? Absolutely not.

[Porsche911R]

Steve Rance said:

Interesting reading this thread again. Also interesting that the ceramic V steels argument still rages on. No doubt that ceramic technology and certainly refurbishment technology has moved a long way during this time. My thoughts remain unchanged. Ill take a decent floating steel set up every time and put the - not insubstantial - cash saving elsewhere.

We run a 997 cup which has a steel floating set up on it as part of our company marketing statergy.10 or so customer days at Silverstone GP with 30-40 customer rides a day (normally 4 laps). The brakes get a lot of absue, there are some big stops at Silverstone, passengers are often well over 15 stone and we carry a heavy feul load for much of the day. Each ride is 10/10ths from the first corner of the ride to the last then straight into the pits, then belt another passenger in and straight out again. Thats all the cooling they get. No other cool down at all and no warm up. We stop at lunch time then run to the end of the day. Often there is thick smoke coming from the front pads while we are in the pits changing passengers. Occasionally they are acually on fire if there is pick up on them. They take a real hammering but function perfectly. No fade, no need to leak bias to the rear to maintain temps. No maintanance needed at all from the driver during the day... and they are good enough for a 50 meter braking point (dry) for Copse, lap after lap. I can rely on them all day. Never let me down.

Would I consider running ceramics? Absolutely not.

And I bet 2 up with a 15 stone passenger and a trick brake set up you cannot lock the wheels at 140mph :-)

If stopping from 140mph on a dead straight at what speed do you think you need to threshold brake to stop a lock up or ABS cutting in ?

PS can I have a drive :-)

I think you are one of the best posters on PH the info is always real and backed up , it's very refreshing.

[bcr5784]

Porsche911R said:

you can out brake an ABS system, and in a lot of cars you can get ice mode if ABS kicks in, hence threshold braking is key on track.

I am in wonder at what people drive like in here. In fact I am not as I have been in many cars on track days and people seem to lean on the ABS and other systems.

Not disagreeing with you - simply saying ABS prevents you locking the wheels. And yes with threshhold braking you certainly can beat some ABS systems. It was commonplace in the early days of ABS. I very much doubt that is the case with the best systems now. You need to under-rotate the wheel by 5-10% to get the best braking and I doubt even the best drivers can do that consistently.

[Neverbeen-too-fast]

Maybe I found something that will answer many questions regarding "surprisingly fast" wear of CCB/CCM.

I myself was very surprised reading this! And - it answers the question why the car manufacturer do not and never speak about the wear characteristics of CCB.

Take a look here - it is from the aircraft industry. I assume that the timings of oxidation are the same with cars - as oxidation should not (largely) depend on disk size.

https://www.iata.org/whatwedo/ops-infra/training-l...

Scroll down to:

3. FACTORS THAT AFFECT BRAKE OXIDATION

All this confirms the experience of hard trackers:

For heavy tracking CCBs are very expensive. For casual trackers / road - CCB ar great - as long as one stays (permanently) as low as possible with temp - over 600 degrees is "financial suicuide"...

I do read about unspecified technilogical progress from bmw to prolong Life drsmatically (press) ... and i Read elsewere about Fibre coating to prevent oxidation.
It seems to be that they manage oxidation quite well below 600. Above that I assume the Discs have only a Lifetime of minutes...

It may also answer why there is so much rumor about how bad washing the CCB is for their life. It is not about water but about possible alcali chemicals.

CCB:

stay cool with water only and enjoy - till the end of the universe

Edited by Neverbeen-too-fast on Tuesday 11th July 11:09

Edited by Neverbeen-too-fast on Tuesday 11th July 11:19

[Kawasicki]

Porsche911R said:

Kawasicki said:

...but I spent three days in Spain doing nothing but braking from 155+ mph, then fiddling with the abs controller to stop initial lock up. Are you sure?

Tell me more.

you have a crap ABS system, or tyres :-), in your own words you changed the ABS setting to stop it kicking in, not your brake pressure !

Strange then that I was getting really short braking distances, with all 4 wheels fully in ABS slip control, painting really nice light grey skid marks from 150 mph to 2mph. Needs a really good shove on the brake pedal though, it felt like the arch of my foot was starting to collapse after three days, though I am fairly slight of build.

[Slippydiff]

Dr S said:

Just focus on what I wrote instead of making things up. Engineers tend to design braking systems fit for purpose. Please tell me in which world does a track exist where you could experience the type of braking scenario (including lack of cooling) that you suggest. I have not found one in my world but judging from the aggressiveness of your posts you must be certain to have found it in yours...

You' appear to have completely missed the point of the "brake dyno scenario" I suggested, hence the "where's the whoosh parrot" question. Early PCCB's wore out prematurely, not because the owners of the cars "didn't do a couple of cooling down laps after a track session", but because they overheated them whilst driving the cars, this in turn caused oxidization of the discs faces, which then wore out prematurely due to mechanical wear, this was then rapidly followed by de-lamination.

As for the "aggressiveness" of my posts ? Well I found out the hard way that the early PCCB's weren't up to the job. So despite doing my due diligence and having my prospective purchase inspected by Reading (who told me the PCCB's on the car were serviceable). They looked like this after the 170 mile drive home from picking the car up :



Sorting the issues cost me a lot of time and heartache :

https://www.pistonheads.com/gassing/topic.asp?h=0&...

But in sorting the GT2 brakes and chassis out, I garnered a huge amount of information about PCCB,s and carbon ceramic discs, along with the manufacturing process/s, but also the workings of the GT2/3 chassis In doing so I also "discovered" Surface Transforms and Center Gravity.

[Polite mode on] So when I read comments such as yours about PCCB's NOT being made of chocolate and requiring a couple of cool down laps to ensure they're longevity, I get a nasty nervous tick that brings out my "aggressive" side......[Polite mode off]

Modern PCCB's are now much better engineered to enable improved heat management, firstly by their size/mass, but also by their internal venting and cold air ducting on the chassis itself. Could you overheat them by abusing them ? probably, but why would you ? They've been engineered to do the job and no doubt have a decent safety factor built into their design, something that couldn't be said of the early iterations.

[Debaser]

Porsche911R said:

go on ?

I think it's really funny, and very strange, that you think it's not possible to lock the wheels (or trigger ABS) at high speeds.

[Mabbs9]

Carbon brake wear is very complicated compared with what we've all been brought up with. It's slightly counter intuitive. Number of applications is more relevant to wear than total energy put in. The max temps aren't too critical but the speed they cool is. Cooling fast increases wear.

They're not well suited to cars on the whole.