An automotive disc brake assembly comprises a disc rotor made of graphite cast iron with a structure of pearlite, and a brake pad made of organic material. The disc rotor has a first thermal conductivity falling in a range from 0.090 to 0.140 cal/cm.sec. DEG C. The brake pad has second thermal conductivity falling in a range from 0.65 to 3.00 Kcal/mh DEG C. The second thermal conductivity falls in a range from 0.65 to 0.98 Kcal/mh DEG C. provided that the second thermal conductivity satisfies the following relationship with the first thermal conductivity: lambda R>/=-0.152x lambda P+0.24 where, lambda R is first thermal conductivity, and lambda P is the second thermal conductivity. The disc brake assembly is successful in improving heat check resistance ability which is substantially influenced by thermal conductivity of the disc rotor and the brake pad.
