One of these brake cooling posts, I will have to post some of my observations of running ducting to the brakes on the Scion race car I work on. We had this awesome ducting setup made, and the rotor temps showed no real difference. Nothing you could tell with the paints. Its making me rethink some of the ways you have to use, and the data that you get from them.Thermal paints.
An effective method of checking maximum disc operating temperature is by using temperature paints applied to the disc AP racing paint kit contains three paints, Green (turns white at 430°C), Orange (turns yellow at 560°C) and Red (turns white at 610°C) plus thinners and brushes.
Shawn, the front pad wear looks to be very tapered based on the 2 top pics, is that correct or is it the angle the pics were taken?Brake inspection for VIR - and fluid bleed.
Temp paint inspected each side. I don't have the key on this, Sean, can you help?
Pad wear - two days at CMP, which is NOTORIOUSLY hard on brakes. I'm fairly pleased.
Temp strip on the caliper for a laugh:
I must admit I'm pleased at this. We'll see how the CCM's continue to hold up to track stress, but so far I'm pleased. I'll also be testing different kinds of pads for this rotor as well.
Cool, thanks for clearing that up Shawn, I guess with those disc you could run concrete friction material and they would be OKIt is correct. Tapered top to bottom and inner to outer. This is similar to the pad wear I was having on iron rotors though. It would be worse, I suspect if the pistons weren't staggered the way they are.
*edit* - the top to bottom tapered wear is similar to the wear I was having before. The inner to outer taper is due to the Enzo sized pad that Stillen chose for this upgrade. The pistons are WAYYY on the outside of this pad, causing the taper. I don't really care, honestly. I will be using normal GT-R pads later though, and I'll compare.
Another safety point - I can probably run to the backing plate on these rotors with little fear. It should be hard to score them.
Shawn,Be careful, you can indeed score the face of these rotors and deteriorate them if the pads run too hot or too thin. You still need to take very good care of them if you want them to go the distance. User SlipR35 has probably used these brakes harder than anyone on here - running through a complete set of the supplied front pads every 50 laps or so. The place is hell on brakes as you would imagine from that kind of wear rate.
I have been reading this and another thread re CCM rotors. I also posted questions re how hard on these CCM rotors, and its COF (Coefficient of Friction) comparing to iron rotors (OE or AP) running with the same brake pad, at the same temperature conditions:Be careful, you can indeed score the face of these rotors and deteriorate them if the pads run too hot or too thin. You still need to take very good care of them if you want them to go the distance. User SlipR35 has probably used these brakes harder than anyone on here - running through a complete set of the supplied front pads every 50 laps or so. The place is hell on brakes as you would imagine from that kind of wear rate.
Something posted by Chris a while back. He goes into details on the CCM's as he was a friction engineer, something I am not.If Stillen's (AP) claim is true that their CCM rotors are indeed ridiculously hard (hardness scale please), I see no reason you have to concern that a brake pad (at any temp), or a steel backing plate (as the pad is completely worn out) can possibly score these CCM rotors.I am hoping that we can get this hardness issue clarified and reconciled.
There is a lot of confusion out there when people hear "carbon brakes". In racing, carbon-carbon (C-C) is used wherever the rules allow it. For high-performance road vehicles, carbon-ceramic matrix (CCM) is the rotor of choice. Carbon-carbon brake systems consume both the rotor and the pads, where CCM brakes are designed to consume only the pad.
There are a few different ways to make CCM rotors. The ones on the Scuderia you mention are made from three pieces, a chopper-gun-like core and two face plies -- and only those face plies are siliconized into carbon-ceramic. The core remains C-C. So far, this style of construction is more delicate and less user-friendly than a full 3D CCM, like those on the STILLEN GT-R upgrade. The 3D version takes longer to make and requires more energy, so they end up being more expensive.
The enemy of CCM brakes is not wear -- they are very, very hard (approaching diamond hard!). The real issue is oxidation. As long as rotor temps are kept below 750°C / 1400°F, they could possibly last the life of the car or even longer. If run for extended periods of time over that temperature, oxidation will start to convert the carbon molecules to carbon dioxide, which just floats away. So it pays to keep track of rotor temps, which is why we apply paint temps at STILLEN before we assemble them to the hats. Cooling kits are a great idea for track use. Keep in mind that the pads will also run hotter as the rotor has less mass to absorb braking energy than iron discs, so the CCM discs will heat up everything around them a bit more.
Now here is another interesting point: If you were to oxidize those Scuderia CCM rotors (or the ones on any Ferrari, Lamborghini, Porsche, Aston Martin, Audi, ZR-1 Corvette, etc.) you get to throw them away after they lose a prescribed amount of mass. With the Stillen GT-R system, surface oxidation can be ground off to where the rotor looks like new again. This can only be done with a full 3D CCM rotor, not the 3-piece laminated type like on the other cars mentioned above as you would grind right through the thin face plies!
If we chose to go with the 3-ply route instead of 3D, we could probably lower the price a couple grand -- and then have to deal with the occasional dissatisfied customer who would have to replace a front pair when they were excessively oxidized or if damaged by putting wheels back on the car. In the service manual for the ZR-1, the service tech is required to place a foam ring around the rotor before removing a wheel. If not, the dealership gets to pay for a new rotor if he chips it. While I certainly don't recommend pounding a wheel against the STILLEN/AP Racing CCM rotors, we are much less concerned about careful, routine service creating such a problem.
Even though carbon-carbon has been around since the 70's (I started working with C-C in 1990), the more recent availability of CCM to the general public will continue to cause confusion until we get further down the road. They are not the same as iron in any capacity other than they are roughly the same shape. We can't expect that after 100 years of iron drums and discs that CCM technology will be completely understood by the masses for quite some time. Then add the fact that they are still changing as companies continue to look for ways to reduce the manufacturing costs.
The rears look good. The fronts are maxing out the limits of the AP paints. The issue with the telltales is that we don't know how much above 610C, the rotor temperatures actually are. I forwarded this thread and info to our new brake manager. In some cases brakes are going to need more cooling. Its one of those things I have talked about a long time. GT-R's and brake cooling. One of my and descartesfools favorite subjects.Any comment about the temp paint changes?
Looks like I'm getting to above the red paints upper limit of detection on the front, despite the active cooling kit.
I can't see the pics. Will have to have a look at them when I get a chance.Pad taper has DISAPPEARED!!!!
Now nice and even. I will get one more track weekend out of this set. Estimated 500 TRACK MILES on these pads so far, with more to go!:
Wouldn't have believed it if I didn't see it myself. Padwear evened out. Looks like I'll get full thickness burn.
P.S. - sorry Sean - high res images, much > 1gb each. Sorry.