01-24
4) Basic Inspection
(1) Horn operation
Listen for the horn sound when pressing the horn pad on the steering wheel. -
(2) Brake operation
Check if there is any abnormal noise, unusually long braking distance, or uneven braking force. If the
brake warning lamp does not go out even after starting the engien or are flashing during driving,
have the brake system checked immediately.
Check the brake pipes and hoses for connection, oil leak, crack or interference after changing the
position of tires. When replacing the tires, check the brake disc for surface condition and wear.
Check the parking brake cable and brake operation. Shorten the checking interval if the parking
brake is used frequently. -
-
-
(3) Exhaust system
Be aware to any changes in sound or smell from the exhaust system. These may be caused by leak or
overheat. Have the exhaust system checked and repaired immediately.
Inspect the exhaust system including catalytic converter. Inspect all the components and body frame
near the exhaust system. -
-
(4) Tires
Unusual vibration of the steering wheel and seats or pulling to one side on the straight and level roads
may indicates the uneven tire inflation pressure or poor wheel balance. -
(5) Steering and suspension system
Inspect the front and rear suspension and the steering system for damage, looseness or missing
parts, signs of wear or lack of lubrication. Inspect the power steering line and the hoses for
connection, leak, crack and chafing. Inspect the drive axle boot and seals for damage, tear or leak.
Replace or repair the system if necessary. -
(6) Engine oil
Check the oil level when the engine is still warm and add the specified engine oil if necessary. -
(7) Coolant
Check the coolant level in the coolant reservoir, coolant conditions (contamination, foreign material),
and hoses for damage and leak. Replace or add the Ssangyong genuine coolant, if needed. -
(8) Engine drive belt
Check all drive belts on the engine for wear, crack and looseness. Retighten or replace the belt, if
needed. -
08-8
1) Front Suspension (Macperson Strut Type)
Front suspension supports the vehicle weight and absorber the vibration from tires. And, in this type of
suspension, the steering linkage tie rod is mounted on the knuckle.
Macperson strut type suspension is the independent suspension which has the spring on the strut
integrated with shock absorber. The lower arm is installed on sub frame and large strut damper is
installed on the knuckle to support the tire. This type of suspension is normally applied to the vehicle with
monocoque body, especially on the front wheel drive type. The upper part with spring is mounted at
body mount and the strut with shock absorber is linked on the steering knuckle.
Advantages ▶
Compact and simple design
Stable wheel alignment
Good load distribution and easy installation
Less effect from tire up/down movement 1.
2.
3.
4.
Disadvantages ▶
Comparatively weak to the impact from road surface and lateral shock due to long strut and single
swing arm 1.
Macperson strut type suspension
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2) Basic Theory of ABS Function
To give you a better understanding of the tasks and functions of ABS, we will first look at the physics
principles.
(1) Stopping distance
The stopping distance depends on the vehicle weight and initial speed when braking starts. This also
applies for vehicle with ABS, where ABS always tries to set an optimum brake force on each wheel. As
great forces are exerted between the tires and the carriageway when braking, even with ABS the wheels
may scream and rubber is left on the road. With an ABS skid mark one may be able to clearly recognize
the tire profile. The skid mark of an ABS vehicle does not however leave any hint of the speed of the
vehicle in the case of an accident, as it can only be clearly drawn at the start of braking.
(2) Brake force on a wheel
The maximum possible brake force on a wheel depends on the wheel load and the adhesion coefficient
between tire and carriageway. With a low adhesion coefficient the brake force, which can be obtained is
very low. You are bound to know the result already from driving on winter roads. With a high adhesion
coefficient on a dry road, the brake force, which can be obtained, is considerably higher. The brake
force, which can be obtained, can be calculated from below formula:
Maximum brake force ▶
FBmax = wheel load FR x coefficient of frictionMh
The braking process cannot be described sufficiently
accurately with the brake forces calculated. The
values calculated only apply if the wheel is not locked.
In the case of a locking wheel, the static friction turns
into lower sliding friction, with the result that the
stopping distance is increased. This loss of friction is
termed "slip" in specialist literature.
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2) Operation of ESP System
The ESP (Electronic Stability Program) has been developed to help a driver avoid danger of losing
control of the vehicle stability due to understeer or oversteer during cornering. The yaw rate sensor,
lateral sensor and longitudinal sensor in the sensor cluster and the steering wheel angle sensor under
the steering column detect the vehicle conditions when the inner or outer wheels are spinning during
oversteer, understeer or cornering. The ESP ECU controls against oversteer or understeer during
cornering by controlling the vehicle stability using input values from these sensors and applying the
braking force to the corresponding wheels independently. The system also controls the engine power
right before the wheel spin synchronized with the ASR function to decelerate the vehicle automatically in
order to maintain the vehicle stable during cornering.
(1) Under steering
What is understeering? ▶
Understeer is a term for a condition in which the steering wheel is steered to a certain angle during driving
and the front tires slip toward the reverse direction of the desired direction. Generally, vehicles are
designed to have understeer. It is because that the vehicle can return back to inside of cornering line
when the steering wheel is steered toward the inside even when the front wheels are slipped outward.
As the centrifugal force increases, the tires can easily lose the traction and the vehicle tends to slip
outward when the curve angle gets bigger and the speed increases.
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ESP controls during understeer ▶
The ESP system recognizes the directional angle with the steering wheel angle sensor and senses the
slipping route that occurs reversely against the vehicle cornering direction during understeer with the ya
w
rate sensor and lateral sensor. Then, the ESP system applies the braking force to the rear inner wheel to
compensate the yaw moment value. In this way, the vehicle does not lose its driving direction and the
driver can steer the vehicle as intended.
(2) Over steering
What is oversteering? ▶
Oversteer is a term of a condition in which the steering wheel is steered to a certain angle during driving
and the rear tires slip outward losing traction.
Compared to understeering vehicles, it is hard to control the vehicle during cornering and the vehicle can
spin due to rear wheel moment when the rear tires lose traction and the vehicle speed increases.
ESP controls during oversteer ▶
The ESP system recognizes the directional angle with the steering wheel angle sensor and senses the
slipping route that occurs towards the vehicle cornering direction during oversteer with the yaw rate
sensor and lateral sensor. Then the ESP system applies the braking force to the front outer wheel to
compensate the yaw moment value. In this way, the vehicle does not lose its driving direction and the
driver can steer the vehicle as intended.
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When the vehicle is driven on a road surface covered with water at high speed, tires do not contact with
the road surface but rotate floating on a thin film of water.
It causes brake failure, lower traction force and losing the steering performance.
To prevent this, increase the tire inflation pressure, use tires with leaf shape tread which is not worn.
However, it is a best measure to drive slowly.
2) Hydro Planing
14-8
If weight is not equally distributed around the wheel, unbalance centrifugal force by the wheel rotation
produces vibration. As the centrifugal force is produced proportional to the square of the rotating speed,
the wheel weight should be balanced even at high speed. There are two types of the tire and wheel
balancing: static and dynamic. Abnormal vibration may also occur due to unbalanced rigidity or size of
tires.
1) Static Balance
When the free rotation of the wheel is
allowed, the heavier part is stopped on the
bottom if the wheel weight is unbalanced and
this is called "Static Unbalance". Also, the
state at which tire's stop position is not same
is called "Static Balance" when the wheel is
rotated again. If the part A is heavier as
shown in the figure 1, add the balance weight
of a weight corresponding to unbalanced
weight from B to A to maintain the static
balance. If the static balance is not
maintained, tramping, up and down vibration
of the wheels, occurs.
2) Dynamic Balance
The static unbalance of the wheel creates
the vibration in the vertical direction, but the
dynamic unbalance creates the vibration in
the lateral direction. As shown in the figure
2 (a), if two parts, (2) and (3), are heavier
when the wheels are under the static
balance condition, dynamic unbalance is
created, resulting in shimmy, left and right
vibration of the wheels, and the torque Fxa
is applied in the axial direction. To correct
the dynamic unbalance, add the balance
weight of a same weight for two points of
the circumference of the rim, A and B, as
shown in the figure 2 (b), and apply the
torque in the opposite direction to the
torque Fxa to offset in order to ensure
smooth rotation of the wheel.
Center
A
B
a
a
Fxa
Fxa F
F
A
B
(a)(b)
[Figure 1]
[Figure 2]
3. WHEEL BALANCE