Idler arms are used on “box steering” or parallelogram steering systems that are usually found on trucks and rear wheel drive vehicles. The idler arm assists the Pitman arm by supporting the steering linkage components as they are moved by the steering gear.
The bracket side of the idler arm mounts to the frame and supports a ball joint on the other side. The idler arm is typically located on the side opposite the center link from the Pitman arm and holds the center link in the correct position.
Idler arms are generally more vulnerable to wear than Pitman arms because of their pivot function. If the idler arm has grease fittings, they should be lubricated at each oil change. Worn idler arms result in tire edge wear, loose or erratic steering and vehicle wandering.
IDLER ARM TYPES
Arm Type – These consist of an arm with mounting points on one end that attach to the vehicle’s frame while the other end is connected to the main body through a bearing.
Bracket Type – This type contains the pivot assembly within a forged housing. It is bolted directly to the vehicle’s frame with the bearing contained inside the assembly.
IDLER ARM LONGEVITY
Idler arms are durable components, and with the proper maintenance and care could last the vehicle’s lifetime. However, depending on driving habits, road conditions, lack of lubrication and other factors, idler arms can become worn or damaged and will need replacing.
TYPICAL SIGNS OF A BAD/WORN IDLER ARM
If the steering feels loose, has extra play or seems difficult to control, or if the vehicle pulls to one side, these may be indications that the idler arm is out of normal specification. These issues should be promptly inspected and dealt with as they present a major safety concern. Should the idler arm completely fail, all steering control will be lost.
REPLACING AN IDLER ARM
The cost to replace an idler arm varies depending on the vehicle and required labor. Some vehicles require replacing both the idler arm and Pitman arm. Replacements may be relatively inexpensive, but the steering components do take some time to properly assemble and test. An alignment is also required when adjusting or replacing idler arms.
