Thinking of buying cross drilled rotors? Well, than you better ask some questions from the manufacturer's engineer (supposing the company has one).

First question would be:

a. What conditions do you take in consideration, when calculating the position of the holes or/and grooves (slots) ?

b. How do you know, the rotor is balanced before and after cross drilling?

c. What is the value (in meters) of the braking distance (at 60 km/h and 100 km/h) in the case of blank rotors and cross drilled rotors ?

d. How do you compensate the decrease of the contact surface between pad and rotor after cross drilling?

e. Is the structural integrity of the rotor maintained after cross drilling and how would you know?

Obviously you may not know the answers (or maybe you do) to all these questions, but you can see how the person answers and feel the degree of his understanding of the problems.