Recently, according to the advances of vehicle manufacturing technology and the fuel-efficient vehicles, the weight of the vehicle body has been reduced and quietness of the vehicle has been increased. So that, as the emotional qualities of cars, such as NVH, are emphasized in recent years. Also required to be established of the effective measure for brake Judder. The Judder was caused by the increase in DTV by the uneven thermo metamorphosis of brake disc and the partial abrasion of disc. In this study, the disc aggression by friction materials was confirmed and the improving methods of friction materials in connection with the abrasive characteristics reviewed of $ZrSiO_4$ each particle size(under $3{mu}m$, $5{sim}10{mu}m$ and over $15{mu}m$). In addition, the study is institute make use of limit for $ZrSiO_4$ raw-material particle size and vol% in friction materials. At the result, the optimum size of $ZrSiO_4$ particles was confirmed about 5 to $10{mu}m$.