Brake Drag Optimization: A Perspective on Virtual and Physical Tools for Developing Near-Zero Drag Sliding Calipers

The ever-increasing prevalence of electric vehicles in the global market continues to push automakers towards more stringent brake drag requirements. As OEMs seek to differentiate themselves with greater vehicle range to offset consumer anxiety as a barrier for entry to EVs, brake caliper suppliers see requirements for zero or near-zero drag at the component level becoming commonplace. Despite this pressure, many practical concerns exist with torque measurement capabilities in the sub 1.0 N-m range. Additionally, the authors have observed an industry tendency to employ suboptimal engineering methodology for assessing drag concerns, with trial and error attempts continuing to perplex engineers more than it provides solutions. This paper will seek to reintroduce to the reader the basic physics of brake drag from a fundamental free body diagram level, review statistical approaches for characterizing the individual forces acting within the caliper, and propose a simple – yet effective – virtual tool for characterizing potential solutions. The virtual tool will be correlated with physical assessments, and the practical challenges of full brake corner drag evaluations will be discussed. Finally, recommendations will be presented for evolving sliding caliper design to enable zero drag.