Rotor for a disc brake assembly and method of making same

A disc brake assembly for an automotive vehicle comprising;

• a rotor which defines a disc having a centrally disposed hub and a plurality of friction surfaces disposed about said hub and generally parallel relative to each other on opposite sides of said rotor;
• a caliper operatively associated with said rotor for engaging said friction surfaces of said rotor;
• each of said friction surfaces including a single continuous spiral groove disposed between said hub and an outer radial edge of said rotor, said single continuous spiral groove including a first portion wherein said groove has adjacent segments thereof disposed radially in side-by-side relation relative to itself and concentrically about said hub with each adjacent segment of said first portion of said groove being spaced from itself by a first predetermined distance, said single continuous spiral groove also including a second portion wherein said groove has adjacent segments thereof disposed in side-by-side relation relative to itself and concentrically about said hub with each adjacent segment of said second portion of said groove being spaced from itself by a second predetermined distance which is different from said first predetermined distance to improve braking of said rotor.

A method of making a rotor for a disc brake assembly including the steps of:

• forming a rotor including a centrally disposed hub and at least one friction surface disposed about the hub;
• and
• cutting a single continuous spiral groove by moving a cutting tool across the friction surface at a first predetermined feed rate and forming a first portion of the groove wherein the groove has adjacent segments thereof disposed radially in side-by-side relation relative to itself and concentrically about the hub with each adjacent segment of the first portion of the groove being spaced from itself by a first predetermined distance and by moving the cutting tool across the friction surface at least at a second predetermined feed rate which is different from the first predetermined feed rate to form a second portion of the groove wherein the groove has adjacent segments thereof disposed radially in side-by-side relation relative to itself and concentrically about the hub with each adjacent segment of the second portion of said groove being spaced from itself by a second predetermined distance which is different from the first predetermined distance.