is to obtain ease in steering and the usual angle of inclination is about three degrees. Without going into an involved explanation of the reason for doing this it may be stated that it is a mechanical principle that the nearer the center of the spindle bolt and the pivot point of the wheel are to an alignment, the easier the car will steer. If it were possible to bring the center of that part of the tire which is upon the ground to a point exactly under the joint of the steering knuckle the arrangement would be ideal. To secure this alignment or to get as near to it as is practical with the accepted Elliot steering knuckle construction, it is customary to tilt the wheel. In the case of the Ford car, a plumb line dropped through the spindle bolt would strike the ground about two inches from the pivot point where the wheel tire rests on the ground. The diagram makes this point clear. It is customary to find the front wheels of large cars dished in the same manner so this point should not be confused with lack of alignment in a horizontal plane which will interfere with correct steering and result in rapid tire wear. Testing Wheel Alignment.-A splendid opportunity is present during the overhauling period for aligning the wheels and axles which should be done to make sure that they have not moved out of their correct position. But little apparatus is needed to make these trials, the outfit consisting of two chairs, two heavy pieces of wood, and two lengths of stout cord. One chair is placed at the rear of the chassis, the other at the front as indicated at Fig. 363. The chairs are located as near as possible to the center line of the machine and after the cords have been adjusted the chairs are spread apart enough to tighten the cords. In order to prevent movement of the chairs when they have been properly placed they may be weighted down with iron or steel parts. The important thing to do is to have the cords parallel to the frame side member and to have the member on the right just the same distance away from the right hand frame rail as the left hand cord is from the left hand frame rail. A common defect of alignment of the front wheels is shown at A. In this case the tie bar is too short and the wheels are nearer together at the back than they are at the front. The opposite to this condition is shown at B, in which case the tie bar member is too long and the wheels are nearer together at the front than at the rear. Either of these conditions will result in uncertain steering and will also produce rapid tire depreciation. Practically all tie bars are adjustable to a degree and steps may be taken to straighten up the wheels by either lengthening or shortening the tie bar as conditions demand. The sketch D also shows the method of testing a rear wheel for parallelism with the frame side member. At C, the method of measuring for alignment of front and rear axles is shown. As will be apparent the rear axle has shifted on its springs and the wheels are not parallel with the frame side members. At D, the axle has moved sideways due to shifting of the spring chairs and the wheels do not track, even though the rear wheels are parallel to the frame side member. It is important that the cords be stretched at a height equivalent to the center of the wheel hubs because some cars are made with considerable gather in the front wheels so that the distance at the rear of these members to the cords would be slightly less than at the front. Then again, many cars have considerable camber in the front wheels which means that the top of the wheels will lean outward, therefore any distances measured above the center of the hub will not agree with those taken below it. By stretching the cord along the center line of the wheel this trouble may be avoided. Universal Joints.-The universal joint is an important element in practically all shaft drive cars, some constructions using but one joint if the propeller shaft is protected by a long housing while other systems employ two universal joints, one at each end of an exposed propeller shaft. Universal joints on many early cars were run exposed and considerable trouble was experienced due to rapid wear of the bearing parts. When exposed there was also considerable difficulty in keeping the joints properly lubricated. The modern forms are housed inside of a casing member, which is not only designed to exclude the dirt and grit from the bearing surfaces, but which is also depended on to retain lubricant. A typical universal joint assembly and the parts comprising it are shown at Fig. 364, A. The main parts of the joint are the yoke member A, and the disc member B. The yoke has bearing surfaces O and P designed to engage two of the pins on the universal joint cross member J. The other two pins fit into the bearing members R and S attached to the disc B. The entire joint is housed in by the cover members D and Z. The driving flange B may be bolted to a corresponding member on the end of a change speed gear shaft or rear axle pinion drive shaft, while the sleeve member A, which is provided with either a square or splined hole as desired, fits on the end of the |