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A review of available information on the effect that brake rotor crossdrilling has on brake performance reveals a wide range of claims on the subject, ranging from ‘minimal effect, cosmetic only’ to substantially improving brake cooling and fade resistance. There are also several theories on why brake rotor crossdrilling could improve fade performance, including crossdrill holes providing a path for ‘de-gassing’ of the brake lining material and increasing the mechanical interaction, or ‘grip’ of the lining material on the rotor. This paper reviews three case studies in which the opportunity arose to compare the performance of brake systems with crossdrilled versus non crossdrilled brake rotors in otherwise identical brake corner designs. The effect of brake rotor crossdrilling on brake cooling, brake output, brake fade, wet brake output, and brake wear rates were studied using both on-vehicle and dynamometer data.

Over the past decade, the automotive industry has seen a rapid decrease in product development cycle time and an ever increasing need by original equipment manufacturers and their suppliers to differentiate themselves in the marketplace. This differentiation is increasingly accomplished by introducing new technology while continually improving the performance of existing automotive systems. In the area of automotive brake system design, and, in particular, the brake apply subsystem, an increased focus has been placed on the development of electrohydraulic apply systems and brake-by-wire systems to replace traditional pneumatic and hydraulic systems. Nevertheless, the traditional brake apply systems, especially vacuum-based or pneumatic systems, will continue to represent the majority of brake apply system production volume into the foreseeable future, which underscores the need to improve the performance and application of these traditional systems in passenger cars and light-trucks.

The modern braking system in the field today may be controlled by over a million lines of computer code and may feature several hundred moving parts. Although modern brake systems generally deliver performance, even with partial failures present in the system, that is well above regulatory minimums, they also have a level of complexity that extends well beyond what the authors of existing regulations had envisioned. Complexity in the braking system is poised for significant increases as advanced technologies such as self-driving vehicles are introduced, and as multiple systems are linked together to provide vehicle-level “features” to the driver such as deceleration (which can invoke service braking, regenerative braking, use of the parking brake, and engine braking). Rigorous safety-case analysis is critical to bring a new brake system concept to market but may be too tedious and rely on too many assumptions to be useful in the early architecting stages of new vehicle development.