One of the dc motor problem is how to positioning the brush of the commutator. Armature reaction on dc motor makes the position of the brush to be changed from its normal position. Commonly in many dc motor, the brush is set permanently from factory. This paper, it will use special dc motor that has a brush changer and discuss the relation between the brush position and motor characteristic i.e. motor speed, torque and mechanical charateristics. From the experiment result, it can be concluded that the best charateristic is found when the brush is positioned on 24° in the left side of the central position. The best motor effeciency is 73,64 %.