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Ive done about 10 track events iver the oast year or so, including 3 events each at road anerica and mid ohio, 2 each at autobahn and gingerman, and once at blackhawk.
After two days each at autobahn and road america, one week apart, with new yellow pagid pads my new porsche oem rotors are heavily cracked! I have a 2009 base carerra 911 C2.
Ive never had race pads before so that is a new variable. But my origi al rotors lasted about 8 track events without cracking. Note I just washed the car so that is why there is water.
Washed car so thats why its wet. Cracking at drill holes front and year. Fronts also uave pervasive cracking on face of rotor surface area when you zoom in
Those don’t look too bad, just getting started. As you progress with your speed and braking and move to race pads you are putting more stress on the rotors and they will show that by cracking. They are fine until the cracks connect the cross drills or reach the edge. these are just getting started.
When I used cross drills I was replacing the rotors once a season. I get a lot more life from solid or slotted rotors, so think abut that direction when you replace next time.
My rule of thumb when I used OEM cross drilled was they were ok until the cracks reached the adjacent hole.
i strongly prefer slotted rotors, even though they don’t look as cool.
Agree with others here that those are not concerning. With track pads come higher temps. I am new to P-cars but in racing with BMW and hondas I measured rotor temps regularly exceeding 1000 degree F. I tend to treat rotors as a throw away and have used cheep Chinese blanks on a 5- series for Daytona 14-hour racing. Never had issues using cheap rotors after 10 years of racing them.
I would replace them. That's just me for knowing the cracks are there will never give me a peace of mind. I would replace them with slotted rotors though.
About a month ago a member was asking about grooving in his rotors but I noticed cracks and offered the following: "However, I would be concerned about the perforation cracks at the crossed drill holes for the rear brake rotors (pretty sure those are the rears). 5mm is the max total length and it looks like you have more than a few that are > 5mm. Time to change out the rear rotors and pads if your measurements confirm that. Also, double check the entire circumference of the front an rear rotors for cracks at the edge. If there are any cracks touching the edge, then that rotor is due for a change out. This is all per AllDataDIY for a 2009 C4S. I suspect that it is the same across most if not all 911s with cross drilled rotors."
I would replace them. That's just me for knowing the cracks are there will never give me a peace of mind. I would replace them with slotted rotors though.
Those rotors are fine, zero wrong with them. My track car has AP J hook rotors which are high quality. If you think those are bad you should see my track rotors. They have so many cracks it is insane. Finally after 3 seasons they are done, but only because the Js are nearly gone
Those cracks are nothing. Many more days of abuse remains.
Try to get some additional cooling—enlarged ducts underneath the wheels is a typical first try solution.
10-19-2019, 04:56 PM
new rotors cracking like crazy!
