Shock Absorber vs. Strut: Understanding the Difference in Car Suspension

Introduction:

A well-maintained suspension system is essential for a smooth and controlled ride in your car. Two key components that play a crucial role in absorbing road impacts are shock absorbers and struts. While many people often use these terms interchangeably, it's important to recognize that they serve different purposes in the suspension system. In this blog, we'll explore the differences between shock absorbers and struts, shedding light on their functions and components.

What is a Shock Absorber?

Contrary to popular belief, shock absorbers do not support the weight of the vehicle. Their primary function is to control the movement of the springs and the suspension. When the suspension moves, the kinetic energy is converted into thermal energy through hydraulic fluid (usually oil). The shock absorber has a piston that moves against the hydraulic fluid, and tiny holes or orifices in the piston determine the resistance of the shock absorber. Modern shock absorbers are velocity-sensitive hydraulic damping systems, offering more resistance as the suspension moves faster. This helps reduce bounce, sway, body roll, brake dive, and acceleration squat.

Components of a Shock Absorber:

A shock absorber's main components include the piston, piston rod, cylinder, mounting, bush, and bolts. The piston, attached to the piston rod, provides resistance from the hydraulic fluid in the pressure tube. The mounting secures the shocks to the vehicle body and suspension, while the bush absorbs vibrations and reduces noise and wear. The cylinder contains the hydraulic fluid and the piston, and bolts fasten the shock absorber to the vehicle's body and suspension. Oil seals prevent leaks and protect against dust and contamination.

What is a Strut?

A strut is a critical part of a vehicle's suspension system, serving as both a damper and a structural support. It replaces the upper control arm and upper ball joint found in conventional suspensions, making it lighter and more space-efficient. Struts perform two main functions: damping like a shock absorber and providing structural support to the suspension. They help control spring movement, support the spring, and hold the tire in alignment. Struts also bear the side load on the suspension, contributing to ride comfort, steering, vehicle control, braking, wheel alignment, and overall wear on suspension components.

Types of Struts:

Two common types of struts are the MacPherson Strut and the Double Wishbone Independent Suspension. The MacPherson Strut is widely used in front suspensions of passenger cars, offering ample space for the drive shaft, low cost, and reliability. On the other hand, the Double Wishbone Independent Suspension is found in luxury cars and off-road applications, providing excellent handling and stability with its A-shaped control arms.

Frequently Asked Questions about Shock Absorbers

1. What are the symptoms of a leaking shock absorber?

Ans: One of the main symptoms of a leaking shock absorber is the presence of oil leaking from the oil seals. This indicates that the shock absorber is worn out and needs to be replaced. If left unaddressed, it can negatively impact the handling and performance of the vehicle.

2. Why are shock absorbers used in vehicles?

Ans: Shock absorbers are crucial components of a vehicle's suspension system. They help smooth out road imperfections and maintain constant contact between the tires and the road, ensuring better handling, stability, and a comfortable ride for passengers.

3. Can shock absorbers be repaired?

Ans: Some shock absorber issues can be repaired by replacing parts like mounts, bushes, pistons, and hydraulic fluid. However, if the shock absorber has covered significant mileage or is extensively damaged, it is advisable to replace it entirely.

4. Where should shock absorbers be replaced?

Ans: Shock absorbers should be replaced at an authorized service station or a reputable automotive workshop. Professional installation ensures the safety and effectiveness of the new shock absorbers.

5. When should you replace a shock absorber?

Ans: If you experience excessive bouncing on bumpy roads, difficulty in steering, uneven tire wear, or extensive dive during braking, it may be time to check and replace your shock absorbers.

6. How many shock absorbers does a car have?

Ans: A typical car has four shock absorbers, one at each wheel. They work together to provide a smooth and controlled ride.

7. How much do shock absorbers cost?

Ans: The cost of shock absorbers varies depending on the brand and type, but on average, they range from around Rs. 3000 for a passenger car.

8. Which shock absorbers are best?

Ans: Some popular brands known for their quality shock absorbers include Monroe, KYB, Bilstein, Gabriel, and Koni. Opting for the same brand and specifications as the manufacturer's original equipment ensures a comfortable driving experience.

9. How can shock absorbers be checked?

Ans: Shock absorbers can be checked by pushing down on one corner of the car and observing if it bounces excessively upon release. Visual inspection for oil leaks or damage is also helpful.

10. How much travel do shock absorbers have?

Ans: Shock absorbers typically have around 2.5 inches of travel in both compression and rebound directions. The travel amount may vary based on the vehicle's suspension design.

11. Are shock absorbers universal?

Ans: While all shock absorbers serve the same purpose, different vehicles require specific shock absorbers with varying specifications to fit their suspension systems correctly.

12. Can shock absorbers squeak?

Ans: Yes, if you hear squeaks when driving over bumps, it could be a sign of a worn-out shock absorber, or it may indicate issues with ball joints or bushings.

13. Are shock absorbers important?

Ans: Absolutely! Shock absorbers are integral to a vehicle's suspension system, providing a smooth ride, steering control, reduced body roll, and improved braking and acceleration performance.

14. Will shock absorbers work upside down?

Ans: No, shock absorbers are not designed to work upside down, except for specific specialty shocks.

15. Can shock absorbers be adjusted?

Ans: Some shock absorbers are adjustable, allowing adjustments in travel and rebound. This feature allows for fine-tuning the suspension for improved handling and comfort.

Conclusion:

Understanding the difference between shock absorbers and struts is crucial for maintaining your vehicle's suspension system. Shock absorbers control spring and suspension movement, while struts serve as both dampers and structural supports. Each component plays a vital role in ensuring a smooth ride, good handling, and stable steering. By keeping your suspension system in top condition, you can enjoy a comfortable and safe driving experience on any road.

Shock Absorber vs. Strut: Understanding the Difference in Car Suspension