In this work, a controllable electrorheological (ER) valve system is devised and applied to vehicle ABS in order to control braking force distribution. A cylindrical ER valve is designed and its pressure controllability is experimentally confirmed. A hydraulic booster is then manufactured in order to amplify the field-dependent pressure drop obtained from the ER valve. Subsequently, the governing equation of the rear wheel model is derived and a sliding mode controller to achieve the desired slip rate is designed. The controller is then realised through the HILS method and controlled responses are presented. In addition, computer animation results for the braking performance under both unladen and laden cases are presented.