[FTS]

So, first time using the carbon ceramic systems and don't much what to expect. I have been doing quite a bit of research and it appears that rotors will last quite a long time if heat is managed properly, specifically the BMW CCB units, which are very similar to PCCBs, will start oxidizing at around 1,300 degF, but BMW recommends staying under 1,120 degF.

So, before the Summit event I put some temp paint on the rotors, 950, 1000 and 1100. Today changing the wheels back I checked the paint and it appears the rotors did reach 950 but stayed below 1,000.

[Trak Ratt]

Paint's a great idea! What brand did you use and is it available locally?

[FTS]

Originally Posted by Trak Ratt

Paint's a great idea! What brand did you use and is it available locally?

I used Tempilaq, very easy to apply, comes with its own cap/brush. I ordered it online from Pegasus, I think it was $80 for all three.

[Jazzbass]

Good info. So how was the M4 on the track?

[TurboPooch]

From the second picture it appears as though the oxidation layer is almost to the backing plate on the pads and it also appears to be a good bit of wear for two track days, especially since some of the weekend was wet. I heard Carson talking about going thru a set of pads already. Are you experiencing the same?

[FTS]

Originally Posted by Jazzbass

Good info. So how was the M4 on the track?

Quite different than a Porsche for sure. The first thing you notice is the weight, particularly under braking. I was quite skittish during this event as it was 1st anniversary of my totalling the GT3 to the day, quite slow (1:32-34s), but I gained more confidence as the weekend progressed.

Overall, the engine was great, no heat issues. The DCT was superb. Amazing amount of tires you can fit underneath: 265 front and 325 rears I used. Shocks are not on par with that of the Porsche, but camber thus far seems OK. Overall handling had a lot of similarities to a 911 in many areas, but also felt very different in other areas. For example, T1-2 I felt exactly how it was in the GT3, in T3 the weight caught me a little off guard, in T4 I had absolutely no confidence, I was off by 20 mph from the GT3, T5-7 were good and similar to GT3, T9 and 10 also felt very close in feel to the GT3. One area that the scared me was being WOT approaching T1 at above 135 mph; it felt as if it was floating around much more than I am used to, so I cut off throttle much sooner. I don't know if that was me, or the car, it just did not feel right.

Very comfortable track capable daily driver would be my summary

Originally Posted by TurboPooch

From the second picture it appears as though the oxidation layer is almost to the backing plate on the pads and it also appears to be a good bit of wear for two track days, especially since some of the weekend was wet. I heard Carson talking about going thru a set of pads already. Are you experiencing the same?

That was not quite my experience. I used the pads that came with the car, since Pagid RSC pads are not yet available. It is hard to tell from the pictures, but only half of the front pads turned silver (they were fuming for 3-4 mins after sessions ), so there is quite a bit more pad material still there that is hard to see in the pics; they did not give up much from original thickness from what I can tell.

It is also recommended to change pads more often than on iron rotors, generally at about 50%, to preserve their heat absorption as much as possible away from the rotors. So, I will change them after another 1 or 2 day event, before a 3-day event.

[nova996]

The temp paint is a brilliant idea, thank you! I will try that on my PCCBs to keep an eye on that.

Is that a wear indicator visible on the rotor? How do you read that? When do you know the rotor is done?

[FTS]

Originally Posted by nova996

The temp paint is a brilliant idea, thank you! I will try that on my PCCBs to keep an eye on that.

Is that a wear indicator visible on the rotor? How do you read that? When do you know the rotor is done?

Wear indicator is visible, yes. Once that circle is broken or looks like it is no longer a circle, it means the outter ceramic coating is done. However, more importantly the inner carbon-fiber reinforced slicon carbide part is what really does the conversion from kinetic energy to heat to slow the car down. The only way to know if you have enough material to do so is to weigh the rotors. Each rotors has a specific minimum weight, and if the rotor weighs less than that it needs changing. The only way the rotor will loose its inner core material is through oxidation, otherwise they don't wear out through the use of the brakes; hence the importance of keeping the rotors below their oxidation temps and the temp paints

I heard that Porsche came up with a speciality tool that basically scans the rotors without weighing them and determine their condition, but I have never seen it, BMW does not seem to have such a system yet.

[ausgeflippt951]

Temp paint is a great idea -- glad to see it worked for you!

Pegasus also sells little heat-activated thermometer stickers you can place on the calipers. They don't last terribly long but would give you a good idea for how the calipers are doing.


Glad you enjoyed the car. I'm still laughing at how much rubber you can fit under there.

[HughA44s]

FTs,

I read with interest your comments concerning tracking your M4. I arrived at a transition to driving a BMW last year from a very different point from you but had almost exactly the same experience. In my case, I went from a 944 to a 330 e46 (with some suspension and break mods) so my staring point was very different. What is exactly the same was the impression of tracking it. Also, my lap times (with some work and help from several black and red group instructors and and two concurrent events at summit) ended up similar to yours. What really caught my eye was the "no confidence in T4" - exactly what I was feeling. The instructors I was riding with keep telling me to use more power but I had trouble doing it (maybe a gonad issue) Also the comment on being unsettled into T1. In my case I was closer to terminal velocity (for that straight) than you would be. Would be interested in what tires you were using? In the end, I had a blast driving it. One other observation, I found that the car was much more track dependent as judged by my lap times in relation to other cars. WG, mid-Ohio, and VIR really brought out the best of it but I am still working on SP.