Ball joints on an IFS are similar to passenger car parts. The ball joints at the top and bottom of each steering knuckle are a distinct wear point. With a floor jack beneath the lower A-arm, vehicle weight will compress the spring and unload pressure from the spindle's ball joints. You can move the tire and wheel at the 6 to 12 o'clock position and feel for loose ball joints. Ball joints cannot be tested under coil spring load or when vehicle weight is on the tire.

Other wear points are the A- or control arm bushings, radius arm bushings (Ford twin I-beam), sway bar bushings, track bar bushings, and wheel bearings. Inspect leaf springs for misalignment or cracked leafs, loose U-bolts, worn rebound pads, a broken center bolt (which allows axle shift), and worn or damaged spring clips.

Steering Linkage Wear Points
Although steering linkage design varies between beam axle and IFS models, the steering linkage joints are of similar design. Steering linkage must pivot and allow for suspension movement. For this reason, tie-rod ends are of ball stud and socket design. Some pitman and idler arms use a ball stud and socket as well.

On older steering linkage, the joints at the drag link ends, or even the tie-rods, will have spring loaded ball cups. An adjustable plug sets a precise load on the cup tension spring. The steering arms or pitman arm have a ball head, which the cup halves capture-these joints, like all others, require periodic lubrication.

When checking for wear, a dry or semi-frozen joint may not show play. Sometimes, it is necessary to grease a linkage joint to force out dirt and debris before testing for play. A seemingly tight ball stud might become excessively loose.

IFS suspension has the most steering linkage joints. The centerlink or relay rod attaches to the steering gear's pitman arm. The idler arm supports the opposite end of the center link. On double A-arm suspension, the idler arm pivots from the right side framerail. The idler arm is a common wear item. Ford's twin I-beam steering linkage has a simpler "Y" design that uses fewer joints and does not require an idler arm.

When a beam axle model has the pitman arm moving laterally, a drag link or "short tie rod" connects the pitman arm to the steering arm at the right side spindle. A long, single tie rod connects the right and left steering arms. Another approach is the fore-and-aft moving pitman arm that moves a drag link. The drag link attaches to the left steering arm at the knuckle. A long tie rod connects the left and right steering arms.

Steering linkage adjustments include toe-in and centering the steering gear. Next month, our discussion will cover the fundamentals of wheel alignment. Steering linkage and A-arm adjustments are central to frontend alignment. Stay tuned!