Strutbearing is typically applied in conjunction with Macpherson sturt. This is Because the Strut comple is directly fixed at Knuckle that has rotational motion by moving of Steering wheel. Strutbearing is positioned next to the insulator. So Fit-in force and Fit-out force between two parts affect directly on assembly facilities, working conditions and quality-related issues. This is why we should to consider engineering the assembly concept. This paper aims to establish reference data of design specification by building up the quantitative Data Base of design factors for engineering assembly concept. In this paper, We set up the major design factors and level which are related to assembly concept and then combine them in various cases for engineering analysis and experiment focusing on fit-in force and fit-out force. Consequently, We checked the correlation as quantitative D/B between design factors and both forces, and the side effect from some design factors