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Adjusting Slack in Rack-and-Pinion Steering

Step-by-step advice for tightening your

The mechanics of steering around corners, chuckholes, and squirrels is something most folks don't give much thought to while driving, and with good reason. Drifting off into a daydream about ball joints, tie rod ends, and control arm bushings while behind the wheel can be hazardous to yourself and others. The modern automobile suspension is the culmination of years of engineering, yet is taken for mundane. While there have been many types of automobile steering systems over the years, the mighty rack and pinion has become the standard for automobiles worldwide, thanks largely to its simplicity, light weight, and durability. Some manufacturers still adhere to the old system of worm gear and recirculating ball steering box, but the majority of vehicles on the road today have a rack and pinion connected to the steering wheel.

Direct Connections

As the steering wheel is turned, the rack and pinion work together to shift the steering linkage and the wheels together either to the left or right at the constantly changing whim of the driver, or errant squirrel. At the very center of the steering wheel is a long shaft. This shaft runs down to the steering rack, and is connected to the pinion gear. The pinion gear is round and has teeth, like most gears. The pinion lives in the steering rack housing. As the pinion turns in direct relation to the wheel, so does the rack. The rack also has teeth like a gear, except the teeth run along the length of the rack, machined into the shaft that is the rack itself. Thus, as the pinion turns around and around, the rack moves back and forth in its housing.

Connected to the ends of the rack are the inner tie rod ends. Flexible rubber boots protect these inner tie-rod ends from road grime and subsequent wear. Another shaft connects the inner tie-rod ends to the outer tie-rod ends. The outer tie-rod ends are directly connected to the steering knuckles. As the rack travels back and forth, the wheels turn left and right. If the steering is feeling a bit sloppy, it may be time to eliminate slack. Over time the rack and pinion will wear slightly and require adjustment.

Tighten Up

While it is recommended that service procedures be followed, the general procedure for rack and pinion preload adjustment is universal. Inspecting the boots, tie rods, and the steering rack for excessive wear is a safe bet when it comes time to adjust the steering rack. Some rack-and-pinion steering systems are manual, but most are of the power-assisted variety. If power steering fluid is leaking from the boots or pinion housing, the seals have likely failed. As specialized tools and skills are required to restore these seals, outright replacement of the steering rack is the best option. If all is well then adjusting rack and pinion preload is a snap.

The key point is to never over-tighten the assembly. Excessive preload will cause rapid wear and can result in dangerous binding. Any tight spots in the steering travel indicate that the preload is too great. Turn the steering wheel lock-to-lock before beginning the procedure to get a feel for free travel. Since most vehicles spend their time traveling in a mostly straight line, turn the wheel slightly off center before adjustment in order to get the rack out of the highest wear area. If excessive slack cannot be removed by adjusting preload, the steering rack or tie rod ends will likely need replacement.