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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.