The objective of this paper is to show how the problem of crack in the joint B-pillar x roof of a passenger car was solved. To solve the problem only the joint was modeled by finite element method, thus avoiding the modeling of the complete structure.In this model was reproduced the levels of stress effects that will cause the crack by fatigue. Once reproduced the boundary conditions, loads and the stress levels, it were analyzed proposals to solve the problem. The basic model contained 10,000 nodes and approximately 9,000 thin shell elements. It was used the software CAEDS version 3.1 to generate the model and it was used as solver the software MSC/NASTRAN version 67.5.It were developped 7 proposals and the best result in the relation cost x benefits, was to change the thickness of roof passing form 0.75 mm to 0.85 mm. With the change the structure will have infinite life, which was confirmed after durability test.