The J-type shape was first seen on the brake rotors of race cars competing in the highest forms of motorsport. Rolloface has transferred this race-proven design for road cars and track cars. They are designed to offer strong initial bite and longevity.
The J-type groove machined into the brake rotor surface are designed to swipe hot gases and brake dust from the rotor and maintain their shape even under hard use. By contrast, the circular holes in a cross-drilled rotor have been shown to form spider cracks under repeated heavy braking usage.