Yikes..... and that's why I went straight to the StopTechs.

 

Here is my answer... I race my car TT and Wheel to Wheel, I race it hard, I win. (just to explain Im not just running autoX or Hpde track days)
I have a tendency to "run it the way I brung it" probly not the smartest thing to do, but then that allows my to brag even more when I win. and Im usually broke or lazy. LOL.
I have never cracked a rotor. (in 4 years) - When I brake, its "hard on" and "quick off" try to make braking straight lines.
Once you see the checkered flag, try not to use your brakes any more than absolutely necessary all the way into the pits.
Park and block your tires so the car does not roll.
Aprox every couple minutes let the car roll about a foot, just moving the chock block back every few minutes for 3 or 4 times, then a couple more times about 10 minutes apart after that. Those few times of rotation allow the rotors to cool without just cooking one section and holding the heat so badly.
Use an OEM rotor or true OEM replacement or Better Rotor, not your part store cheap blanks.
About half way through the life of your pad, get the rotor turned to just put a fresh surface and it removes those little surface micro cracks you see.
I have never ran a brake duct, but I will install them soon (I cook my brakes sometimes and they will get glassy about half way in a race if I dont watch it).
Ive ran Carbotech Xp10,8 for years, now running Xp12,10
Hope this helps.

 

So how often do you swap your rotors? just once the micro cracks start to get bigger and closer to the edge? or by number of races or heat cycles?

 

I used to run xp10 on street tires, never cracked a rotor, pads lasted a season (16 events).

Then ran on R comps and xp10 didn't work too well, so got xp12 but that pad only lasted 5 events. Still no cracked rotors...

Then now I run DTC-70, no fade good bite, but rotors start vibrating and develop micro cracks.

It seems Carbotech is rotor friendly, but the pads don't seem to last as long. Pads are more expensive than rotors, so it seems much cheaper to replace rotors than pads every few track days... I do believe I need brake ducting though...

Here's a vid of an on track rotor crack incident in an S2000 at 190kph
http://www.youtube.com/watch?v=RLB8dmVIlGE

 

[/quote]So how often do you swap your rotors? just once the micro cracks start to get bigger and closer to the edge? or by number of races or heat cycles?
[/quote]
The micro cracks are normal, and appear rather quickly, so you cant keep those from happening. I will start the season with a fresh turn or I will put a new set of rotors when I put on a new set of pads. Usually about half way through the season -july area (about 8-10 track days) I will pull off the front rotors and get them turned, or about half pad.
But if your car is a dedicated track car etc... I still recommend Brake Ducts.

 

I have a few questions for those who have cracked rotors and a few for Brian. I'm on the fence for buying a bbk. I'd like to keep the car stock, but no amount of money is more important to me than safety.

What tires are you using when you cracked your rotors?

Do you have brake cooling ducts or similar?

Are you using your brakes during your cooldown lap?

Brian, wouldn't using the brake to stop the car after moving it a foot every couple minutes increase the likelihood of cracking?

 

Not everyone needs brake ducts. You'll know when you need them when you start "smearing" you brake pads and pad life gets so short you really start to contemplate the cost of brake pads and actually consider that your wife/girl friend might be right--that this track hobby is just too damn expensive, and then you come to your senses and order the ducting

 

lol.. I'm at this point now. The front pads (XP10) are lasting 2.5 track days. Brake ducts are next.

 

I'm "smearing" my brake pads now but I'm not concerned with pad life--I just don't want to crack my rotors. Break pads can be replaced, you can't go back and make up for track time lost while replacing your rotors.

I understand the goal of moving the car a foot at a time during cooldown, but I'm trying to understand the proven method of doing so. Maybe I should have put more emphasis on the using the brakes part, but that's my concern. I don't see any other way other than having another person move the chock while you move the car. The understanding I have from this thread is that people crack their rotors more often when using the brakes after the calipers have not cooled properly. I imagine it takes more force and duration to crack than you would apply just moving the car a foot, but I'd hate to crack my rotors while performing an action that's only purpose is to prevent the rotors from cracking.

 

What "force" is being applied when you move the car a foot?

This is my take on cracking stock rotors either with or without brake ducts. If you're in the top 20% of S2000 lap times you're pushing the thermal limits of the stock brakes and the stock rotors will eventually crack. The hairline cracks will grow until the rotor truly cracks. Some people at some tracks crack stock rotors every 2 or three days at the track. Track configuration affects the cool down lap which may affect rotor cracking. The condition of your calipers may affect cracking--if your pads are dragging as you come into the paddock more heat may be transferred from the calipers to the part of the rotor under the caliper.

Brake ducts don't seem to affect rotor cracking--guys with and without them crack rotors at a high rate. Brake ducts will increase pad and brake fluid life and reduce brake fade on track.

I was cracking rotors on Summit Main (or in the paddock) almost every weekend when I upgraded to RacingBrake.com rotors (with stock calipers) and it solved my problem. I went a full year, 23 events (27 hours) before I had to replace the RacingBrake.com rings. I never missed a track session to change rotors.