just noticed very small (less than 1/8") cracks on one front rotor (06 997S) the cracks do not run between the holes just start at hole and move outward,I've done several DE's ,what's the point of concern as to replacement
any thoughs on why just see on one rotor ,changed front pads prior to last event.

 

I would change these rotors sooner then later...in other words when your pads wear out you need to replace the rotors as well.

 

Porsche says 7mm.

Watch them close and err on the side of caution. Have seen rotors fail twice on the track and both were total losses but the drivers survived.

 

I'd say just keep on watching them. The advice I have from several reputable sources is that until the cracks meet up with each other, you are ok.

 

I'm a belts and suspenders type of guy. I'd replace them now. They're not going to heal. This is not like a cosmetic item. You may miss when they get to/beyond Porsche spec. Or it might happen while you are driving or tracking.
Kind of like dropping your motorcycle helmet and then asking if it was beyond the safe height.

 

If you can get a good photo of your rotor posted here, that would probably help.

 

I've gone through plenty of sets of front rotors on the track. I replace them when they just about reach the outside of the rotor or the center hub. By then they are almost reaching hole to hole as well. What's the rate of expansion of the holes? You should be able to tell and then project out how many DE events you have left. Post a photo and we'll guide you

 

pics of front rotors

 

You've got plenty of life there... When the cracks start to connect hole-to-hole or reach the hub or outside edge of the rotor, that's when you need to replace them.

 

I agree that they are fine for now, but I wouldn't push them right to the end. I would definitely change them when the pads wear out, whether that be tomorrow or in a few months. They will not get better.

 

+2 change them soon, don't push them too much more. Those are stress cracks due to extreme heat cycles cause by heating and cooling usually under track conditions.

-steven