ULD-32 Series Drilled Straight Vane Vented Iron Rotors feature a two row, 64 hole pattern that alternates between and directly over each vane. Each hole is deeply chamfered to eliminate any stress points that could result in premature cracking at the drill holes. The drilling process removes an average of one pound from each rotor. Rotating and unsprung rotor mass is reduced by as much as 12%.
Caution on drilled rotors: There is a common mis-perception that rotors are drilled to improve cooling. The reduced mass of a drilled rotor will dissipate its retained heat quicker, but it also builds up heat a much faster rate. The decision to use drilled rotors should be solely based on the merits of the lower rotating and unsprung weight, and Nt for improved cooling. It is Nt wise to use drilled rotors in sustained high heat on hard braking tracks unless the team budget affords a high frequency of rotor and brake pad replacement.