In order to balance an assembly line one has to deal with different concerns as to the way to distribute operations to achieve takt times. Nowadays the complexity of assembly operations don't allow the company to maintain a work balance, which affects the inequity of the workstations' time and also generates non value added activities that is reflected in the total cycle time. The manufacturing plant of this study manually produces bus chassis, and has two assembly lines: urban chassis (UC) and foreign chassis (FC). The purpose of this research paper is to decrease the operator headcount 20% and to increase de value added to 59% in the assembly line. In order to achieve this paper's main objective, the research team used a Lean Six Sigma approach and DMAIC methodology. The activities completed were generating a balance proposal with the reduction or elimination of non value added activities through Kaizens. This paper is relevant for operations management professionals since it represents one of the most studied issues in manufacturing assembly lines, and provides an integrated approach combining different tools to solve this problem in a multinational company.