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The method of friction between ceramic discs and pads work differently than iron discs.
With iron discs it is the friction between the disc surface and the pad surface that provides the braking force, but with ceramic discs it is the friction between the pad material that has been laid onto the disc surface and the pad itself that is what provides the braking force.
After properly break in, what you would expect to see on the surface of the rotor is a nice uniform, reflective layer, which signifies the transfer of material from the pad onto the rotor*. If the transfer layer is patchy or streaky then this would indicate that the pad is operating out of its temperature window. Pitting on the surface is the initial signs of disc wear, where the carbon in the disc is oxidizing.
CCM rotor surface is as hard as a diamond, so no brake pad can ever wear the rotor down. The only possible cause that can damage the rotor is from over-heat that causes carbon to oxide and lose its weight, rotor surface becomes pitted which will wear the brake pad down like a sharp grinder. This is the point when the rotor require replacement or re-furbishsing.
OE requires rotor weight check with instrument and complicated process, so to help user better understand we have published an article - "How to determine when to replace CCM rotor ring"
However we suggest "rotor surface check" is an easy and more practical way to check the healthiness of CCM rotors - If your brakes performs well, rotor surface looks good, and brake pad wear is normal then you should not be worrying about the weight.
*Transfer of layer from the brake pad to CCM rotor is a fusion process which can only take place with a right sintered compound under a high temperature that only CCM rotors can generate (not iron rotors)
There is one irrefutable law on Rennlist that gives me comfort like a warm, fuzzy blanket. Somewhere, somehow there are people here who know just about EVERYTHING about a Porsche.
There is one irrefutable law on Rennlist that gives me comfort like a warm, fuzzy blanket. Somewhere, somehow there are people here who know just about EVERYTHING about a Porsche.
I have been racing professionally since 2004 and I have worked with several different brake manufacturers on developing pads and rotors for the cars I have been racing. To name a few Hawk, Performance Friction, Cobalt, Stoptech, etc.
A sintered pad is highly abrasive on a metal rotor surface area. The most common use of a sintered pad is on motorcycles due to them using a stainless steel rotor. The coefficient of friction on stainless steel is a lot less than cast iron and the sintered pad gives a lot of bite into the rotor material. This gives a feeling of lots of bite and braking force when using these materials together. The down side is the big bite also produces a higher rate of rotor wear.
So here you are advertising a high wear brake pad with a high initial bite as a way to heal a carbon rotor. Yes there are pad materials deposited onto the rotor but there is also going to be a high rate of wear on the rotor itself due to the highly abrasive characteristics of the pad. This is the reason you are seeing the rotor surface be smoothed down in the images. There is rotor material that is being taken away in these photos. There is not a brake pad out there that does not place wear on a rotor. And the material that is being deposited as you are advertising does not replace the rotor wear at the same rate. If this is so then you need to produce to us the evidence that the rotor is staying the same thickness and size.
Here's the deal. If you really want to convince us that you have a pad that heals a CCM rotor and makes it last longer then produce evidence to use that the pad does this. Showing us pictures of smooth rotor surfaces does not mean the rotor is lasting longer. These images do not show us the rotor is "healed". Give us measurements that show the rotor is actually healed. Don't give us videos of some dude in a Camaro going faster on a race track as evidence. Nothing you have given us so far makes for a convincing argument other than the marketing words you are using to sell a product.
CCM rotor is totally different from iron rotor in material and characteristics. Even the way the friction force is generated between the rotor and pad is not the same (see my earlier post)
Here is the article I published after extensive research with contents duly verified by Chief Engineer of Surface Transforms - Geoff Whitfield that should be able to help members with a better understanding of two different type of rotor material.
CCM rotor is as hard as a diamond, no brake pad can ever wear the rotor down. It's actually a wearing process that works the other way around, CCM rotor grinds the pads material (lining) down. Especially when the rotor surface is pitted it becomes so abrasive that can instantly turn the (semi-metallic) brake pad into dust and wear down to backing plate which we see all the time (see those pics posted from a Ferrari Speciale).
Just like the semi-metallic pad, not all sintered brake pads are made the same, during development we also tested Carbon Lorrain sintered pads (made for racing iron rotors) on ZR1 CCM rotors, so we how it worked on CCM rotors.
Nonetheless a properly formulated sintered pad, although still will give up upon a pitted CCM rotor, but because it's full metallic so the wearing process is more gradual, and this fusion process as I said earlier can only take place between CCM rotor and sintered pad at substantial higher (than iron) temperature, and this is a "healing" process through the passing off friction lining to the rotor surface.
During this process the pad wear rate will be higher than normal, but once the surface is healed, the rotor surface is now smooth and protected thereafter the pad wear rate will become normal. And of course if the sintered pad is installed when the rotor is new then the wear rate will be more consistent during its life.
Last edited by RacingBrake; 05-19-2017 at 09:07 PM.
Reason: Adding ST Chief Engineer's name
So, if one uses a sintered pad right from the beginning in CCM rotors, then there will never be a need to change rotors as they won't wear?
I was writing a reply as you posted this question, and the answer is yes. The sintered pad will still wear to make up the film loss between the pad and rotor in a normal way, but not as when a rotor is pitted.
We used micro-meter to check Russ's CCM rotors yesterday as he was preparing this weekend's race at Auto Club Speedway in Fontana, the 3rd we did this thickness check, and can confirm the rotor thickness has not changed at all from day one we saw his deteriorated CCM rotors with pictures posted in this thread.
Some members asking the question about those drill holes. With sintered pads the holes only are "covered" by a thin layer of metallic film on the top, which can be easily poked through; unlike those run on semi-metallic pads , the entire hole is "plugged" (almost welded) and filled with melted resin emitted from the pad which is as hard as you can't imagine, and we haven't fond a way to remove them yet - May be someone here can share his experience.
If a "CCM rotor is as hard as a diamond, no brake pad can ever wear the rotor down" as you state, how does the CCM rotor get pitted in the first place?
What could have caused damage to a CCM rotor is over-heat i.e. running the brake over the threshold temperature (~700C) when the carbon will oxidase resulting the rotor weight loss, and surface gets rough and pitted.
What could have caused damage to a CCM rotor is over-heat i.e. running the brake over the threshold temperature (~700C) when the carbon will oxidase resulting the rotor weight loss, and surface gets rough and pitted.
This is interesting, so in theory If an owner with ceramic brakes does proper cool down laps with his car, them even pccb should last forever also?..
So when all this material transfers to the rotor from the pad does the CCM start to show now brake dust like a iron rotor and pad? Could you use these pads on the factory pccb and see the same results of material transfer? And would this save someone from having to replace his pccb from too many track days? Or would the heat from tracking still cause the burning away of the carbon?
05-17-2017, 03:13 PM
