The paper concerns evaluation of the coefficient of friction characterising a friction couple comprising a commercial brake disc cast of
flake graphite grey iron and a typical brake pad for passenger motor car. For the applied interaction conditions, the brake pressure of
0.53 MPa and the linear velocity measured on the pad-disc trace axis equalling 15 km/h, evolution of the friction coefficient μ values were
observed. It turned out that after a period of 50 minutes, temperature reached the value 270°C and got stabilised. After this time interval,
the friction coefficient value also got stabilised on the level of μ = 0.38. In case of a block in its original state, stabilisation of the friction
coefficient value occurred after a stage in the course of which a continuous growth of its value was observed up to the level μ = 0.41 and
then a decrease to the value μ = 0.38. It can be assumed that occurrence of this stage was an effect of an initial running-in of the friction
couple. In consecutive abrasion tests on the same friction couple, the friction coefficient value stabilisation occurred after the stage of
a steady increase of its value. It can be stated that the stage corresponded to a secondary running-in of the friction couple. The observed
stages lasted for similar periods of time and ended with reaching the stabile level of temperature of the disc-pad contact surface.