Correlation of Lining Properties with Brake Pedal Feel

Pedal feel is one of the first customer touch points during a driving experience, and as such can be an important contributor to quality perception and customer appeal. Many brake system design characteristics contribute to pedal feel, and although not the largest contributors, the brake linings play a role. Friction material properties that influence pedal feel include: friction level, in-stop friction rise, ambient compressibility and hot compressibility. These properties have been measured on a series of commercial friction materials intended for passenger cars and light trucks. Vehicle tests have also been performed to compare objective and subjective evaluations of pedal feel for the different linings on the same vehicle brake system. The testing was designed to identify the contribution of the linings to the brake system's responsiveness and feel. This paper will discuss the correlation between friction material properties and vehicle tests for pedal feel. It was observed that lining properties had some correlation with objective data collected during vehicle tests. Subjective data collected during a 2-day drive evaluation with 23 drivers did not correlate with objective results. Subjective ratings did not show statistically significant differences between linings. This result suggests that lining contribution to pedal feel is more subtle than other factors.