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Wandering Woes?

Wrestling with your steering idler arm

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.

To inspect the pivot bushing, with the vehicle's wheels pointing straight ahead, firmly grab hold of the arm near the connecting ball joint and attempt to move it up and down. If anything more than barely perceptible "play" is detected, it will have to be replaced. Inspect the arm for external damage, including impact. If any is present, replace it. Examine the connecting ball joint by applying force to the joint's shaft tip and bottom with a pair of large parallel jaw locking pliers, being extremely careful not to pinch your palm, or stray fingers, between the plier handles (a distinct possibility if the jaws slip off the joint). Again, if you observe anything beyond barely perceptible play, replace it.

The procedure for replacing the arm will vary depending on which type your vehicle has. Here are a few replacement tips that will be helpful, covering some important points of interest for all types:

> Acquire a service manual for your specific vehicle and follow the directions closely, observing any notes that outline dangers, cautions, special tool requirements and uses, other removal and installation tips, as well as fastener tightening torque values.

> Before you begin to remove, separate, or unbolt anything, mark the position of the arm against its frame mounting point. A fine tipped grease pencil or even light colored spray paint (if you don't mind the look) are a couple of decent choices for doing this. Many arms have adjustment slots where the mounting bolts pass through, so it's in your best interest to mount the new part in the same place as the old one.

> If separating the connecting ball joint is required, after loosening the retaining nut, leave it on the joint shaft by a few threads. This way, when you separate the joint, the resulting immediate steering linkage movement will be contained (by the nut) until you're ready to put your separating tools down and put your hands on it. This makes a safety difference, especially if you are working on your back and in close quarters with these components.

> Don't panic if there are slight physical differences between the original and replacement parts. The bolt pattern and point-to-point measurements should be identical, as well as any "clearance relief" features.

> After installing the grease fittings in the new arm, make sure to lube it properly (yes, with a grease gun), as these components do not come pre-lubed for use.

> It may be necessary to have an alignment shop make final adjustments to your work. This would be especially true if the original arm had been knocked out of adjustment prior to your replacing it.

So there you have it: a greater understanding of your steering linkage and, hopefully, a vehicle that now goes where you point it.