McLaren MP4-29 - exposed rear brake discs 23 June 2014
In Austria McLaren took the unusual step of exposing their rear brake disc to the wheel rim. This is typically done to channel some of the heat generated by the brakes into warming up the tyres. There is a balance to be struck to avoid overheating the brakes, and while exposing the disc is usually an effective solution at the front of the car it is normally less so at the rear, where heat can be generated more simply by a touch of wheelspin. Indeed the two ends of the car require different philosophies. At the front, teams will look to direct airflow into the brake duct, through the disc and then have it exit through the outside of the wheel. At the rear, in contrast, teams still want to take air into the brake duct (red arrow), but then want it to exit on the inside of the wheel in order to reduce drag.