A multi-component idler or pulley that may be used with a belt and pulley system of an automobile is disclosed. The multi-component idler may have an external idler housing coupled to a mounting hub that is designed to be connected to a mounting surface of the belt and pulley system. The axial position of the external idler housing may be adjustable relative to the mounting hub using a threaded engagement or a plurality of shims between the components. The external idler housing and the mounting hub may be fastened to each other by bolts once their positions are adjusted relative to each other. Different types of external idler housing may also be used with the mounting hub. In this way, the serpentine belt of the belt and pulley system may be adjusted based on the user's needs.