SUSPENSION SYSTEM 437 SUSPENSION MAINTENANCE AND INSPECTION OF SUSPENSION SYSTEM (A) Maintenance of suspension system A suspension system takes a tremendous amount of load during normal vehicle operation. Bumps and potholes in the road surface cause constant movement, fatigue and wear of the shock absorbers, or struts, ball joints, bushings, springs, and other components. Suspension system problems usually show up as abnormal noises (pops, squeaks, and clunks), tire wear, steering wheel pull, or front end shimmy (side-to-side vibration). Suspension systemwear can upset the operation of the steering system and change wheel alignment angles. Thus proper service and maintenance of suspension system are necessary as they greatly increase the roadability, reliability, and vehicle life. (a) Suspension Bushing Service Rubber bushings used in the inner ends of front lower arms and rear semi trailing arms are prone to wear and should be inspected periodically. Worn control arm bushings can let the control arms move sideways. This action causes tire wear and steering problems. To check for control arm bushing wear, try to move the control arm against normal movement. For example, pry the control arm back and forth while watching the bushings. If the control arm moves in relation to its shaft, the bushings are worn and must be replaced. (b) Ball Joint Service Worn ball joints cause the steering knuckle and wheel assembly to become loose on the lower arm. A worn ball joint may make an abnormal sound when turning or driving over a bump. If any of the symptoms are found, replace the lower arm assembly. (c) Shock Absorber Service Worn shock absorbers will cause the vehicle to ride poorly on rough roads. When the tire strikes a bump, a bad shock absorber will not dampen spring oscillations. The suspension system will continue to rebound and bounce. This move is then transferred to the frame, the body, and finally to the passenger compartment. Loose or damaged shock absorbers produce a loud clanking or banging sound. To check shock absorber condition, visually inspect the shock absorbers for any signs of leakage (oily wetness) or damage. Also, check the bushing on each end of the shock absorber for being smashed or split. Make sure that the shock absorber fasteners are tight. (d) Coil spring service Coil springs require very little periodic service. Spring fatigue (weakening) can occur after prolonged service. The fatigue lowers the height of the vehicle, allowing the body to settle toward the axles. These settling or sagging changes the position of the lower arms. This condition also affects the ride and appearance of the vehicle. (B) Inspection of strut and shock absorber Before replacing a strut and shock absorber please verify following things first: 1. Understanding customer’s complaint: 1.1 Is the complaint related to front portion or rear portion of car? 1.2 Is the complaint related to particular type of road (e.g. over speed breaker etc.) and driving speed? What time of the day the problem is noticedmore? 1.3 Is the problem continuous or is it intermittent? 1.4 Has the problemstarted recently or has been there for long time? 1.5 Has there been any components changed from OE (original Equipment) fitment? 1.6 Have any extra accessories not recommended by TATAbeen fitted? 1.7 What is the loading of car/no. of persons seating and its use? 2. Preliminary investigation of complaint on car: 2.1 Check tire pressures as per specifications. Correct it, if required. Test drive the car over range of roads which includes city road, rough road, over speed breaker and highway patch. Compare impressions with those of customer. 2.2 Lift the car on hoist and look closely at the suspension and transmission related parts. Ensure that all nuts and bolts are tight and end play of various linkages is as per set norms. Noise is heard many times due to loose parts or fouling of the strut body or shock absorber body with any loose parts near the suspension or incorrect end play for clutch / brake linkages or cracked / broken drive shaft gaiter / boot.
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