CHAPTER VIII

FAULTS IN CHASSIS COMPONENTS

Chassis Types-Dismantling a Chassis-Straightening a Lent Frame-Trussing a Weak Frame-Repairing Cracked Side Member-Care and Repair of Springs and Spring Parts-Compensating for Steering Gear Deterioration-Drag Link and Tie-Bar Repairs-Testing Wheel Alignment-Radius Rods, Torque Members and Control Linkage-Universal Joint Forms and Troubles-Front Wheel Adjustment-Muffler Faults-Chassis Lubrication -Locating Acetylene Gas Leak.

EVEN after the power plant and gearset have received attention, here are numerous points about the chassis of the car that should e inspected if a thorough overhauling is called for. The chassis f any well built car will need but very little attention if the arious parts are well oiled until it has been used from ten to fteen thousand miles. After this distance has been covered, the otorists will probably be annoyed by a series of squeaks and rates, even though the engine and gearset are in perfect running ndition. These rattling noises indicate wear at a number of latively unimportant bearing points, and even though the depreation is slight, the looseness at the multiplicity of small joints Il produce a noise that will be unmistakable whenever the car operated on other than perfectly smooth highways. Among some the things to be looked for are wear in the various control kage members, sagging or bent frame side members, loose cross mbers or gusset plates, due to rivets having loosened up in sere; stiff action of the springs, due to rust accumulating between leaves; looseness in the steering gear and steering connections, of alignment of the front and rear wheels, looseness of the el hub bearings, and numerous other conditions that will be umerated and discussed in this and the following chapter.

Chassis Types.-Before discussing the points to be inspected. and the manner of making repairs when defects are found, it may be well to describe briefly some of the typical chassis constructions in order that the novice repairman may get an idea of the relation of the parts in cars of conventional design. The side and plan views of a National four-cylinder chassis are shown at Fig. 339, all the important components being clearly indicated. This may be considered a good example of high grade car construction in which the power plant and change speed gearing are separate units. As is apparent, the engine may be removed from the frame without disturbing the change speed gearset while the gear box may be taken out without requiring the removal of the engine. The general construction of this chassis is conventional and follows established automobile engineering practice. It has the virtue of having the parts readily accessible so that repairs may be easily made without disturbing other components except those that are to be worked upon.

The plan view at Fig. 340 shows a chassis of recent development produced by the Cadillac Company which is provided with an eight-cylinder V engine having the transmission gearing incorporated as a unit with the engine crankcase. This construction is more accessible than the usual unit power plant is, owing to the design which permits of removing the transmission case from the engine. base without disturbing the power plant. In all other respects. this chassis follows conventional practice. The important parts are clearly shown and no difficulty should be experienced in identifying them on the actual chassis.

The repairman will be more often called upon to repair motor trucks in the future than he has been in the past on account of the increasing popularity of the heavy duty vehicle. The chassis. construction in the main follows the design established in pleasure car practice, excepting for the use of much stronger parts and a tendency to use standard structural steel shapes for frames instead of the special pressed steel side members commonly found in pleasure car service. The average truck chassis will have a pronounced overhang over the front and rear axles in order to obtain a body of sufficient size without unduly increasing the wheel base. Gear

driven trucks do not differ materially in construction as far as relation of parts is concerned from pleasure cars of the present-day type. The worm drive and double reduction axles are rapidly gaining favor and the conventional side chain drive construction to which most of the trucks have been built is gradually being displaced by the more modern forms having a live axle instead of the fixed non-rotating member shown at Fig. 342. It will be remembered by those who have had automobile experience, dating a number of years back, that many of the powerful pleasure cars were fitted with side chain driving systems. The power transmission was to a jack shaft which was practically a live rear axle having sprockets at the axle ends instead of wheels, and from that member to the rear wheels, which were revolved on a nonrotatable axle by means of driving chains. The process of taking down a motor truck chassis and the points to inspect for depreciation would not differ materially from that used in repairing a pleasure car assembly. Owing to the use of solid rubber tires, a motor truck is subjected to much more vibration than a pleasure car, and considerable more attention should be given to the running gear parts, as these may become loose much sooner than on the pleasure car, where all of the load is carried by very resilient pneumatic tires.

No treatise on automobile repairing would be complete without showing details of the Ford model T automobile, which is the most widely used motor vehicle in the world. The reader's attention is directed to the very clear sectional view shown at Fig. 343 for an idea of the arrangement of parts on this universally used motor car. The various parts are clearly outlined and may be located by following the leader lines to their termination at the arrow point. The other end indicates the name of the component. The plan view at Fig. 344 gives an idea of the appearance when viewed from the top.

Dismantling a Chassis.-The various steps incidental to dismantling a motor car chassis to give all parts a thorough overhauling is shown at Fig. 345. The plan view showing the appearance of the chassis of a Locomobile car at A denotes the appearance after the body and fenders have been removed. It is always ad