Shock absorber and suspension

Shock absorbers are the heart of your vehicle's suspension system. They absorb the effects of uneven surfaces, reduce vibration and keep the tyres in constant contact with the road under all driving conditions. Stability and safety therefore depend on them.

Shock absorbers control the movement of the springs, damping rapid compression and rebound movements. They also prevent the tyres from losing contact with the road surface, which could lead to aquaplaning and extended stopping distances as well as irregular tyre wear.

Vehicles in the more prestigious market segments are fitted with electronically controlled shock absorbers and a dedicated ECU.

The forces generated by a vehicle in motion are extremely complex and very difficult to control, as they occur along many different axes.

In the architecture of a suspension system, the purpose of the springs is to support the weight of the vehicle and to absorb the stresses imparted by the road surface, keeping the vehicle body in the correct attitude with respect to the road. Springs are continuously subject to movements of compression and rebound.

Springs are subject to wear: over time, continuous stress leads to fatigue and causes them to lose their elasticity. Springs gradually lose their ability to return to their original size as the result of stress-induced fatigue. Used springs will therefore be longer than new ones.

There are many good reasons for monitoring the condition and functioning of the springs in your vehicle's suspension, and changing them as soon as fatigue is detected. For a start, springs in good condition ensure easier driving and better directional control. They also extend the working life of the shock absorbers and other suspension components (including the tyres) and maintain the correct clearance between your vehicle and the ground.

When replacing springs as the result of fatigue or breakage, always replace them in right and left pairs<. It is also best to replace the shock absorbers at the same time (again right and left together).

As is the case with shock absorbers, replacing just one spring will cause imbalance between the wheels concerned, leading to significantly poorer braking and handling.

The control arms also form an integral part of the suspension system as they connect the wheels to the chassis, permit steering and allow the shock absorbers to oscillate.

The rubber and metal bushes on which they are mounted also limit the transmission of vibration from the road to the passenger compartment.

When driving over rough surfaces, always take care to avoid hitting holes and bumps at high speeds, as accidental impacts can easily damage the suspension's control arms. Frequent driving over bad road surfaces can negatively affect the performance of your suspension system.

Wheel bearings are mechanical devices used to reduce friction between two mating parts that rotate on the same axis. Wheel bearings play an essential role in allowing the wheels (driven or non-driven) to rotate with respect to the chassis while supporting the loads applied to them.

Bearings consist of a number or rolling elements (balls or rollers) fitted inside a temperature-resistant cage, plus two retaining rings.

So how can you tell if a bearing is defective or worn?
Wheel bearings are subject to wear but cannot be adjusted or serviced. They must therefore be replaced as soon as you perceive noise coming from the wheels at speeds between 50 and 75 mph.

Wheel bearings can deteriorate as the result of:

• Impact
• Damage to other components of the suspension system
• Normal wear over time

Worn or damaged bearings can affect road holding and cause rapid wear in other wheel and suspension components. Ball type wheel bearings must be replaced as soon as you perceive noise coming from the wheels.

Constant velocity joints are important mechanical components between the gearbox and the wheels. They transmit torque and power from the gearbox to the drive wheels, thus generating traction. They also assist the action of the shock absorbers.

Dust and dirt are prevented from entering the CV joints by boots made from thermoplastic elastomers (materials chosen for their ability to resist aging, thermal shock and accidental impact). Original CV joints distributed by Mopar_® are made from special, boron and chromium enriched steel to ensure resistance to high temperatures and greater reliability.

While CV joints are designed to last for a very long time, many factors can reduce their useful life and make replacement necessary:

• Absence of grease (caused by a broken boot or loose boot clamps)
• Harsh driving conditions (frequent urban and off-road use)
• Extreme hot and cold temperatures
• Impact

Have your CV joints thoroughly checked every 2 years.