In the recent trends, the automobile systems like transmission, suspension, brake, clutch are controlled through the wire systems called drive-by-wire concept, by replacing mechanical components, without affecting the functions. The advantages of the wire systems are the elimination of mechanical components and quick response when compared through conventional systems. In this work, we design and fabricate a Magnetorheological Brake (MRB) instead of a conventional brake like disk, grum and ABS brake which are currently used in automobile systems. The features of the MRB are no mechanical moving parts, less weight and quick response time. In this MRB, the Magnetorheological (MR) fluid is filled in the gap of outer casing unit and inner disk. The MR fluid has the change of rhological properties under magnetic fields. Commercially MR fluids are very costly. In this work we have prepare and charaterise the MR fluids. Next to the preparation, based on the fluid preparation, we optimize our design throught the COMSOL software. Based on the optimized design value we had design our MRB. Optimum design is found using Nelder Mead optomization technique combine with finite element simulations involving magnetostatic and heat transfer analysis finite element models are built to provide a means to analyze the performance of the MRB.