Wandering Woes?

Not having your vehicle go where you direct it is disconcerting, to say the least. On urban freeways or expressways, where higher speeds and close quarters prevail, this problem can be undeniably scary. A common cause for vehicle "wandering," along with other symptoms related to some sort of imprecision traceable to the steering system, is often the steering idler arm. Other symptoms include a "pull" to one side, noise while turning, or noticeably irregular tire wear.

Steering Systems
Although all vehicles do not come equipped with this component (you won't find one on a rack-and-pinion steering system, and generally not on a vehicle with unitized front "frame rails"), many do, including a number of different SUVs, light trucks, and passenger cars. If the vehicle has a steering gearbox, whether power assisted or manual and it's mounted to a front frame-rail section (either as part of a complete frame or a bolted-in subframe), chances are it has an idler arm. Some vehicles even have two.


Steering systems that include an idler arm as a component part generally have a symmetrical steering linkage configuration. In other words, the links are approximately the same length, and they attach correspondingly to the same places on either side of the vehicle, with each side being sort of a mirror image of the other. The idler arm, at least in terms of function, is the mirror image of the steering box "sector shaft" (for output) and attached "Pitman Arm." The idler arm bolts to the opposite-side frame rail, which would be the passenger side on your typical left-hand-drive vehicle.

Inspection
Once you've raised the front of the vehicle (while observing manufacturer's recommendations for safe lifting and securing of the vehicle for working underneath), you can determine if it has an idler arm. Or, hey—just consult your service manual. Safely remove any shielding underneath that would obstruct your view or access to the arm and you're now ready to inspect it.

Components
The idler arm has three component parts: The pivot bushing, the arm, and the connecting ball joint. Usually they are serviced together, so if there is a problem with any one of these parts, the whole unit will have to be replaced. On some units, the pivot bushing and the arm are separable, and the arm may not "house" the ball joint assembly.