Idler arms are used on vehicles with steering box style systems. Idler arms are normally attached directly to the center link, and they support the front steering components because they attach to the body of the vehicle. On some light-duty trucks, two idler arms are used.
Idler arms allow the steering system to pivot left to right, while keeping the body isolated from this movement. A pivot built into the arm permits sideways movement of the linkage, and an internal bearing allows for low friction movement of the joint.
Arm type — arm type idler arms consist of an arm with mounting points on one end that attach to the body of the vehicle, while the other end of the arm is connected to the main body through a bearing.
Bracket type — bracket type idler arms contain the pivot assembly within a forged housing, which bolts directly to the body of the vehicle with the bearing contained within the assembly.
The purpose of the idler arm is to support the center link and to ensure the center link is always at the proper height. The position of steering linkage must be parallel with the control arm. Optional steering linkage position maintains directional stability and minimizes wear on the tires.