Chapter 17 Wheel Alignment Procedures 367 Copyright by Goodheart-Willcox Co., Inc. Checking Ride Height Check the ride height as was discussed in Chapter 6. If ride height is incorrect, adjust the height if the suspension uses torsion bars or replace parts as needed. Note: Before deciding that ride height is incorrect, check the backseat, trunk, or pickup bed for excess weight. Remove excess weight before proceeding with the height check. The importance of aligning the vehicle at its correct curb weight is discussed later in this chapter. Checking for Worn Parts Once the vehicle is properly positioned on the rack, raise the front and rear wheels to check for worn parts. Do not skip this step. It is impossible to align a vehicle with worn or damaged parts. Caution: If the vehicle is equipped with an electronic suspension system, open the trunk and turn the suspension switch off before raising the vehicle. Raise the suspension so the ball joints are unloaded. On a suspension with the spring on the lower control arm, place the jack under the control arm. On suspensions with the spring on the upper control arm or around the MacPher- son strut, place the jack on the frame. On solid axles, place the jack under the axle. With the vehicle properly raised, perform a shake test, which was discussed in Chapters 6 and 10. Grasp the wheel at the front and back and shake it. Th en grasp the tire at the top and bottom and shake it. If the vehicle has an off set strut assembly, it may be necessary to grasp the wheel at about 45° counterclockwise from the top and bottom and then shake it. If the wheel moves excessively in any direction or makes knocking or clunking noises, look for worn or loose parts. As a general rule, looseness when the wheel is shaken from the top and bottom indicates worn ball joints or very worn control arm or strut rod bushings. Worn tie rods or other steering system parts will cause looseness when the wheel is shaken from the front and back. Loose or worn- out wheel bearings usually cause looseness in all directions. If looseness is detected, have an assistant shake the wheel while you look for worn parts. Sometimes it is necessary to pry on parts using a pry bar. On a few vehicles, the tie rods will be looser when the wheels are on the ground. Once the shake test is complete, visually inspect the suspension for wear, damaged seals, improper adjustment, or loose fasteners. Check the lower ball joint, upper ball joint (when used), control arm bushings, stabilizer bar bushings, and strut rod bushings. Check the steering gear, pitman arm and idler arm (when used), relay rod, and all tie rod ends. Check the shock absorbers and struts for leaks. Check the operation of the power steering system and ensure that the power steering reservoir is full. If the vehicle has any kind of electronic suspension system, make sure the warning light is out and no other problems are evident. Check the drive shaft or CV axles, as applicable. Look for looseness, torn boots, or obvious dents or bends. Shake or twist all fl exible joints to uncover any looseness. Checking Tires and Wheels Inspect the vehicle’s tires and wheels for damage, Figure 17-11. Tire defects were discussed in Chapter 13, Driveline and Wheel Service. Carefully note tire condi- tions that might indicate an alignment problem. Th e chart in Figure 17-12 shows some common tire defects and their possible causes. If the tires were recently rotated, rear tire condition will be a sign of front end problems and front tire condition will indicate rear problems. Check the tire size and air pressure. You cannot align a vehicle when the tires are at diff erent air pressures, are of diff erent sizes, or when one tire on an axle is worn and the other has ample tread. Add air or replace tires as needed. Spin the wheels to check for badly bent rims, dragging brakes, and loose wheel lugs. Checking for Underbody Damage Check all suspension and steering parts for bends, scrapes, and other signs of underbody damage. Procedures for inspecting these parts were discussed in earlier chapters. Carefully check the vehicle’s frame at front and rear for kinked areas or bends. Check for obvious severe setback on the front wheels, especially when collision damage is evi- dent, Figure 17-13. Th e simplest way to check for setback is to measure the distance from the rear of each tire to the fender opening, Figure 17-14. If the setback varies by Cupping (low spots) Impact cut Bulge Crack in wheel Dent Ford Figure 17-11. A tire and wheel with common types of damage identified. Check all tires and wheels closely before proceeding with alignment.