Cracks in rotors

BGTV8

Cracks that extend to the edge of the rotor mean the rotors are toast.

Brake judder on the track and no judder on the road usually means you have hard spots on the rotor from heat soak at the end of a track session.

When a session ends, don;t park the car and leave it, you need to move the can forward 2 feet every minute or so such that no single spot on the rotor stays under the hot pads for more than a minute of so - which leads to differing hardness in the rotor

Also, what pads are you using on the track .... same as DD pads ?

And do you have any rotor cooling set up ?