It is important to keep in mind that that the radiation phenomena becomes more significant when the temperature of the emitting body is higher than 450-500ºC.
It is evident that in the engine, due to its high working temperature, radiation is important. However, the purest example of radiation is the brake disk, as opposed to conduction, where all the components are in contact, and convection, that involves a turbulent movement of fluids.
A conventional casting brake disk can reach temperatures higher than 700ºC and its planar geometry makes it a radiating surface for the steering and suspension components around it.