We just wanted to let everyone know that Ford released a new design front brake rotor for the 2015+ S550 Mustangs that have the 4 Piston Front Caliper. This change was made a couple of years ago but there has been on going confusion of the correct part number.
The original configuration was vented out at the front wheel rather than from the backside of the wheel. This has been referred to as 'reverse cooled' which is not accurate(it still centrifugally pumps air from the center up through the vanes to the outside OD of the rotor), more accurately it was front-side or wheel-side cooled. For the majority of Mustang owners street driving, this was never an issue.
Mustang owners that wanted to Auto-X or Track their Mustangs in HPDE/Time Trials quickly found out heat management was an issue. While conventional ducted cooling to the hub would dissipate some heat through radiant cooling(Cooler air passing over the backside brake rotor will remove heat-Like blowing on a spoonful of hot soup), the issue was the inability to duct positive pressure air flow of lower temperature air through the cooling vanes to cool the braking surfaces evenly, from inside the rotor.
This new rotor design, Ford Part Number: KR3Z-1125-J (Motorcraft Part Number: BRRF-448) is a direct replacement for all 2015+ Mustangs that utilize the 352mm x 32mm rotor used with the 4 piston caliper. This part has been available for a couple of years and recently checking stock with our distributors plenty are currently available.
Being that is a "conventionally" cooled designed, where the air enters the rotor on the backside at the hub and exits via the vanes through centrifugal pumping, a conventional ducted brake cooling system will be as effective as previous generation Mustangs.
This rotor weighs 28-29 pounds, so it has plenty of thermal mass, and when proper cooling is installed it will be able to handle much more thermal load created by racing brake pads on track. Because this brake system is on the majority of Mustangs built since the S550 Chassis was introduced, you will likely be able to locate one quickly near your track event, even on a weekend, in case you need one.
The other advantage to this new rotor is maintaining your stock 17-18" wheels, not being bumped to a new class due to a different brake system or wheel size. Consumables are also less expensive with this brake system. If you have your services performed at a Ford Dealer just confirm that they are installing this rotor during a brake service.