Measuring
Important: For vehicle alignment to be accurate, the shop floor must be level in every direction. The turn plates for the front wheels must rotate freely without friction, and the alignment equipment must be calibrated as directed in the alignment equipment manufacturers maintenance procedures and intervals. Western Star dealers must have proof of this calibration history.
Precision instruments and equipment are needed for accurately measuring and adjusting wheel alignment. Refer to the operating instructions provided by the wheel alignment equipment manufacturer. Before checking or correcting wheel alignment, make sure the vehicle is at curb weight. Curb weight is the weight of the unloaded vehicle complete with accessories and full fuel tanks. If a road test is necessary, the route should be one that allows full left and right turns and full stops. It should also include a length of straight, level road to check the steering wheel position during straight ahead driving. During the road test, note any steering effort and possible roughness. Check for looseness, too much wheel play, any tendency for the vehicle to lead in one direction, and for pull during stopping. Note the position of the steering wheel while driving on a straight, level road. If the steering wheel is not in the straight-ahead position, refer to in the Western Star 47X and 49X Workshop Manual for the alignment procedure.