Crack Whores

So, a day after MGCC Sandown sprints, I felt this shuddering when I was braking from 60 KPH or more. I then discovered that my front rotors had cracked. The left one has two small cracks and the right rotor has one crack that is more prominent. These are almost 2 years old and have been used and abused for roughly 25,000 KM of road and track days.