The steering idler arm is an important component of a motor vehicle, providing essential support to the operation of the steering system. An idler arm is employed in what is known as the parallelogram type of steering system. Modern vehicles are typically designed with either a parallelogram or a rack and pinion steering system. Parallelogram systems use a gear box. This gear box has a pitman arm, which connects to a centre link. When the steering wheel is turned, the pitman arm enables the steering gear box to rotate and move the steering linkage.

The role of the steering idler arm is to keep the centre link in a position that is parallel to the surface of the road, whilst allowing the link to swivel to both the left and the right.  Thus, it is designed to provide swivel movement at the same time as offering resistance in the upward and downward direction.

If the steering idler arm is not operating properly, the vehicle is likely to suffer from “road wander” and excessive play will be present in the steering wheel. In such circumstances, the steering idler arm should be replaced to avoid consequential damage to other parts of the steering mechanism and/or or the vehicle’s tyres.