Chapter 17 Wheel Alignment Procedures 373 Copyright by Goodheart-Willcox Co., Inc. know two things: what the correct specifi cations are and what devices are needed to make adjustments. Th is infor- mation is available in service literature, as discussed earlier in this chapter. Th e next sections discuss general alignment procedures for front and rear axles. Always adjust the rear axle before the front. As mentioned earlier, the toe should be adjusted last on any axle. Manufacturers usually list alignment specifi cations as a range, such as +1/2° to +1 1/2°. Anywhere adjustment within the range is acceptable, but the most accurate settings are usually in the center of the range. In the above example, the ideal setting would be +1°. However, the experienced tech- nician may want to set the alignment near one end of the range based on past experience. Sometimes the technician may even set some alignment specifi cations outside of the range to compensate for other vehicle or operating condi- tions. Discuss this with your instructor before setting the vehicle to anything other than factory specifi cations. Adjusting Rear Wheels Note: If a two-wheel alignment is being performed, the following procedure can be skipped. Except on those few vehicles with four-wheel steering, the rear wheels do not aff ect steering. Th e most common signs of improper rear-wheel alignment are uneven tire wear and noise. If the camber or rear toe is off severely, handling problems may occur. Remember that there is no adjustment for caster on the rear wheels. Caster primarily aff ects steer- ing eff ort and, therefore, is not needed on the rear. Some alignment machines are equipped with a por- table viewing unit. Th is unit can be taken to the rear of the vehicle while making rear-wheel adjustments. Rear Camber Several adjusting devices are used to set rear camber. To make the adjustment, locate the adjusting devices. If neces- sary, raise the lift to gain access to the devices. Note: Many technicians prefer to leave the rack on the ground for more accurate measurements during the adjustment process. Others prefer to raise the rack for easier access to the adjusting devices. If the rack is somewhat flexible, the readings may change when the rack is raised. Consult with your instructor before deciding which method to use. On many cars, eccentric cams are used to adjust rear camber. See Figure 17-23. Sometimes these cams are located under covers or placed in hard-to-see locations. If a cam is used, loosen the locking bolt then turn the cam to obtain the correct camber. Sometimes a special wrench can be used to make turning the cam easier, Figure 17-24. Aft er setting camber, hold the cam in position and tighten the locking bolt. If the camber is adjusted by slotted holes in the strut assembly, loosen the nuts and bolts holding the strut to the slot in the frame. Usually only the top hole is slotted. Push or pull the strut (or the tire) until the camber reading is cor- rect. Th en hold the suspension part in position and tighten the nuts and bolts. For best results, have an assistant tighten the nut while you hold the suspension part. If the vehicle uses threaded rods as a camber adjustment device, loosen the locknuts holding the rod to the frame and turn both nuts in the same direction to shorten or lengthen the rod until the proper camber is obtained. Th en, tighten the nuts and make sure the camber has not changed. Th e camber on some vehicles without a factory camber adjustment can be corrected with special bolts, Figure 17-25. Lock washer Eccentric Frame bracket Control arm Nut Bolt Eccentric Control arm Eccentric and bolt assembly Special adjusting wrench Frame bracket Specialty Products Corp. Figure 17-23. A rear camber-adjusting bolt in an eccentric cam assembly. Specialty Products Corp. Figure 17-24. A special wrench used to turn a large hex- shaped eccentric located inside the frame bracket.