Brake Thread - OEM Ceramics vs OEM Steel

[v8 omfg]

DS2500's, at the time only listed for the C6,
They were ordered with OEM pads, the Ferrodo would not fit unless part of them was cut off, so OEM were fitted with these new AP discs.
Less than 2k and they were humming,
And as I typed before, the advantage was so nominal I must have missed it.

[IanH755]

Thanks for the info, the "H" at the end of the Pt No means DS2500 (ferodo's weird naming ). Do you know what part needed trimming/cutting, was it the friction material or the metal backing pad? As the C6/7 calipers are "supposed" to be the same yet the pads didn't fit I'm trying to find out what the difference might be between the calipers.

[rtd]

Just out of interest all of the owners who have had/have ceramics fitted to their cars, how many of you have actually put your cars on a track?

[Shinobi675]

See this is why I love this forum we have our own playground

So... My question as a starter to a sensible conversation on this... We can expand to more complicated scenarios next.

A billiard table smooth stretch of straight track. Two cars of the same weight and tyre sizes, one oem ceramics, one oem steals.

Both have brakes warmed up to operating temperatures.

They both stop from 120-0 from the same line, both are onto the abs as soon as they can.

Which car stops shorter and by what rough percentage?

[IanH755]

If the cars have identically sized brakes they should be virtually the same on the 1st application (as shown in the Autocar vid). Then the car with the steel discs will take slightly longer to stop with each subsequent application as the heat build up adversely effects the performance (usually the disc will be upto it's max temp of 700'c by the 10th application).

The Ceramic will stay at the same distance consistently regardless of the number of applications.

One thought regarding the RS6 sepcifically, the ceramics have a much bigger swept area (more pad in contact with the disc face) than the steels disc so I would have thought that the Ceramics should be able to reach the tyres limit of grip in a quicker time than the OEM steels discs. So in the test given above, due to the greater swept area I would think the RS6 with Ceramics would stop in a shorter distance. If both cars had the same sized swept area then it would be equal for the 1st application.

So the performance of the Ceramics is never in question, however when steels discs are tested in real life the results can be different than those I expected to see. For example, Car & Driver magazine did an extremely well thought-out series of tests on all types of cars from Sports to SUV/MPV's etc. They found that neither the Chevy Corvette Z51 or Porsche 911 Carrera S tested changed their stopping distances regardless of the number of applications (http://www.caranddriver.com/features/the-power-to-stop - page 4 is sports cars) which I'm quite surprised about although it would have been nice to see a greater number of stops carried out during each tests - say 20.

Also, neither of those cars above car is an RS6 with Audis well documented "poorly cooled" OEM steel discs which I still think would be more likely to perform as expected and have longer stopping distances during repeated stops.

From my own personal experience I found the OEM steels, OEM Fluid and Textar pads (pads fitted by previous owner) to fade quite heavily after 5-10 stops. The fade was felt as a much softer pedal with further travel with a heavily reduced performance despite the pedal position (longer stopping distance) which suggests it was fluid fade from excess heat rather than pad fade from out-gassing which is felt by a hard pedal.

After swapping to AP Racing discs, ATE Superblue fluid and Ferodo DS2500 pads I have not had any pad or fluid fade since despite heavy use. However the pedal does travel slightly further during repeated heavy braking from very high speed (160mph+) but the performance didn't change i.e. same stopping distance just slightly more pedal travel needed; and at legal speeds the pedal feel doesn't change regardless of applications. I put this down to better cooling of the disc, better disc/pad material and a better fluid which has the ability to cope with excess heat.

*edit* - spelling is awful!

[Shinobi675]

See I like that. Well thought out and fact based!

Sweep area is definitely a factor, let's call it 250ms difference at the 120mph. That's a distance of just over 10m. 250ms reasonable?

The fade on my first lap of the ring was bad on mine. 5k in and they were gone. Had to change my driving a lot for the rest of the laps. Was far harder on the brakes for far shorter. Helped but still faded like crazy, that's all oem setup.

[IanH755]

Without actually calculating the difference in swept area I wouldn't be able to guess accurately enough for it to be worth anything to be honest.

[Shinobi675]

That's fair enough

[don0301]

I have standard discs, DS2500 pads, superblue and HEL lines.

I did the VW Phaeton mod, and that made a noticeable difference to braking (in a good way)

Cost me about £100, well worth it in my opinion (to a standard set up)

[IanH755]

Shinobi - Something else to consider (which I've only just though about) is that both versions of the RS6 disc use the same master cylinder supplying the same brake pressure to both setups. So regardless of pad swept area, the force applied to the discs (through the pads) will be the same for both types of disc as the master cylinder pressure will have to be spread out across the larger ceramic pad, reducing it's felt pressure but being felt over a larger area as opposed to the smaller steel pad which has a greater felt pressure but over a smaller area. However the difference in pad material between the two will make a bigger difference than the pads size.

I *think* that makes sense anyway

Don - The OEM steel discs really suffer so much in the cooling department (poor internal design) so anything you can do to help there will be a benefit, and with the Phaeton mod fitting so perfectly I'm surprised it's not something Audi themselves had thought about.

[Surrey Sam]

Ian - Apologies if the picture really caused you offence, it was meant as light hearted fun. I have now removed it.


If we're going to clean up the thread. Then can you please link to where an owner has said their Ceramic brakes have failed after only 3 laps of the Nurburgring (twice). I've not seen it and that certainly seems to form the basis of your argument about ceramics not being track suitable. The only scenario I can think of, would be where the pads caught fire in the carpark after not being cooled down enough and thus causing damage to the disc. I've seen this happen but the ceramic material can't be blamed for that damage, just the end user.

[IanH755]

Hi Sam, thanks matey, I was being a bit over sensitive by that point anyway so I apologise too.

Nurburgring - I think it was a C7 owner in the C7 section (think it was that thread?) but my basis for my "ceramics are easier to damage on the track than steel ones" opinion is from mainly from -

a) The manufacturers like (Surface Transforms - point 9, Movit and Brembo who claim 1400 track miles max on a new disc (so less on a part worn one)

b) Dozens of Porsche owners who swap their PCCB's for steel when on the track due to the cost of replacement discs. Porsche seem to have the highest amount of owners on the track so a good dataset. Also google "PCCB damage" and theres lots of posts on Rennlist.com & PistonHeads Porsche area etc.

c) Stories on forums like the C7 guy, various general Pistonheads threads etc.

Then dozens of pics of destroyed discs from stone chips from gravel traps to over heating causing delamination (Audi uses CCM rather than CCB tech for their disc) -

Porsche PCCB Melted -



Corvette CCM Delaminated from 10 track days -



Ferrari CCM Delaminated and stone chipped edges -



Again, none of this effects their performance which is better than a steel discs performance (absolutely, no-one has ever said otherwise) and if I could afford to replace ceramic discs annually or more then I would, but the best compromise for my personal use is bigger steels as I can afford multiple steel discs.

[classba]

Ian, I have owned both my cars with ceramics for years without a single damage so I cannot understand why you would want to change the ceramic discs on a yearly basis. They are good for at least 80k road miles.

Ian....What I really want to know is, how often do you track your car and how many times have you been?. You talked about the Porsche boys etc... what you have forgotten is that they are track orientated and the C6 is definitely NOT.

[rtd]

Ian, I have owned both my cars with ceramics for years without a single damage so I cannot understand why you would want to change the ceramic discs on a yearly basis. They are good for at least 80k road miles.

Ian....What I really want to know is, how often do you track your car and how many times have you been?. You talked about the Porsche boys etc... what you have forgotten is that they are track orientated and the C6 is definitely NOT.

David here you go again with the road use issue Ian, has not said ceramics are no good on the road he is talking about their performance on the track.

And what relevance is it if you have owned a car with ceramics I do, you never tracked your C6 nor have I. The discussion is regarding their performance and behaviour when tracked.

And who said the C6 isn't track orientated? Any car can be tracked it's just are you up to doing that, putting your car through it and being able to stomach the ensuing bills as a result of it - Ian and Tom regularly track their cars and full props to them I don't because I don't want a possible big bill due to some issue at the end of it.

There used to be an owner on here few years back who was at formula 3 level and he had a C6, and trust me he did stuff with that car which defied believe well for me anyway - when I had the pleasure of being a passenger in his car across some a & B roads.

[classba]

Ian, I have owned both my cars with ceramics for years without a single damage so I cannot understand why you would want to change the ceramic discs on a yearly basis. They are good for at least 80k road miles.

Ian....What I really want to know is, how often do you track your car and how many times have you been?. You talked about the Porsche boys etc... what you have forgotten is that they are track orientated and the C6 is definitely NOT.

David here you go again with the road use issue Ian, has not said ceramics are no good on the road he is talking about their performance on the track.

And what relevance is it if you have owned a car with ceramics I do, you never tracked your C6 nor have I. The discussion is regarding their performance and behaviour when tracked.

What is it that you don't understand here.... The C6 is a barge and is NOT a track car.. the guys here are all talking about tracking them etc so my questions remains... how often do they track the C6 and how many times have they been. This is vital because, if they only maybe track the barge once a year, why the feck would they care about how well or not well the ceramics perform when 99.99% of the time, the car is used on the road.

Also, Ian has stated that he would like to change the ceramic discs on a yearly basis..WHY?.

I go edit as well... you are talking about my mate Adam...

Lastly, you seems to like blowing smoke and answer questions for others. well done mate.