A worn idler arm would affect which alignment angle?

The reason that a worn idler arm would affect the toe alignment angle is tied to its function within the steering mechanism of the vehicle. The idler arm helps maintain the proper geometry of the steering linkage, particularly in vehicles with a parallelogram steering configuration.

When the idler arm is worn, it can create excessive play or movement in the steering linkage. This movement leads to misalignment of the front wheels, specifically causing the toe angle to change. The toe angle is the directional angle of the wheels relative to the centerline of the vehicle; if the idler arm is compromised, the wheels may point inward or outward incorrectly.

Therefore, monitoring and addressing any wear in the idler arm is crucial for maintaining proper toe alignment, ensuring that the vehicle handles correctly and wears tires evenly. This dynamic underscores the importance of steering components in overall vehicle alignment and performance.