Among the numerous suspension configurations available, the multilink suspension system has emerged as a top choice for automakers seeking to achieve the perfect balance between handling and comfort. 

This article aims to provide a comprehensive overview of the multilink suspension system, exploring its principles, components, benefits, and drawbacks, as well as its application in modern vehicles. Discover how this system has become the go-to choice for modern vehicles that aim to impress.

What Role Does Suspension Play in Driving Confidence and Comfort?

As the sole component in contact with both the vehicle body and the road surface, the suspension system plays a crucial role in automotive design. Without a good suspension system, even within a powerful powertrain enabling high-speed driving, there is only a constant fear of losing control.

On the other hand, no matter with features such as high-end audio systems and massage-ventilated seats, if the suspension performance is subpar, these amenities cannot enhance the overall comfort. Therefore, a well-designed suspension system is undeniably the key factor in determining whether a vehicle instills confidence in the driver and ensures the satisfaction of the passengers.

What is Multilink Suspension?

Automobile suspension can be classified into various forms, and selecting the appropriate suspension system is a crucial decision. Different suspension systems directly impact the vehicle’s performance and driving experience, and the choice depends on what tasks the automaker envisions for the vehicle.

For instance, when an automotive manufacturer aims to create a vehicle that provides both an ultimate comfort experience and excellent handling performance, cost is not a consideration. In this case, a multilinks suspension system is often the ideal choice. This is because a multilinks suspension can offer precise control over the position of the tires, achieving a perfect balance between comfort and handling. The following sections of this article will provide a brief explanation of the multilinks suspension, aiming to offer readers a basic understanding of suspension concepts.

What are the Characteristics of a Multilink Suspension System?

Definition

The definition of a multilinks suspension is somewhat ambiguous, with each automaker having its own criteria. Generally, it refers to a suspension system composed of three or control arms on a single wheel. While it is called a multilinks suspension, some manufacturers also refer to the configuration as a double-wishbone suspension when there is an upper control arm, splitting the lower control arm into two. This arrangement is alternatively known as a double A-arm or still classified as a multilinks suspension, e.g. BMW 7 Series (G11) & M-BENZ S-Class (W222)

BMW 7 series g11,g12 font suspension control arms 2015-2021 double wish bone
BMW 7 series Front suspension (G11,G12 2015-2021)
Mercedes Benz S -Class Front suspension (W222 2013-2020)

These two images show the front suspension of the Mercedes Benz S-Class and the BMW 7 Series. It is clear that both the wishbone type upper arm and the separate lower arm look almost identical.

BMW 7 series brochure
Mercedes Benz S-Class brochure

However, when we look at the official brochures from Mercedes Benz and BMW for the S-Class and 7 Series respectively, we find that their suspension names are different. BMW refers to it as a double wishbone, while Mercedes Benz calls it a multi-link. Therefore, whether it is called a multi-link or a double wishbone, sometimes it is just a difference in name while the actual design is the same.

Configuration

The axle position is determined by multiple “I”-shaped control arms on the vehicle body or subframe. At the other end, these arms connect to the knuckle or other control arms, with bushing serving as buffers at the connection points. The specific number of control arms can range from 3 to 5, depending on the manufacturer’s considerations regarding geometric changes during suspension travel, compensation for chassis geometric during cornering, and the emphasis placed on control capability.

Link or Control Arm

In the context of a multilinks suspension system, the suspension arm can be referred to as either a control arm or a link, and the two terms do not have a clear definition.

Geometric Characteristic

When a vehicle is moving, the suspension system is subjected to various forces from different directions, including all the drivetrain (forward and backward forces), engine braking (forward and backward forces), and braking (forward and backward forces), vertical impact forces (due to changes in vehicle weight caused by body weight and uneven road surfaces), and lateral forces (steering).

These forces can impact the original alignments of the chassis. Therefore, the primary objective is to minimize the influence and try to keep the position when the tire is experiencing those forces.

  1. When the vehicle experiences body roll, multilinks are able to work individually, so that can maintain the camber as possible. This ensures that the contact area of the tires with the ground is consistently maximized, which becomes particularly crucial in today’s prevalent increase in wheel size and aspect ratio.
  2. Suppressing changes in the toe during suspension travel, mitigating the occurrence of roll steer1 induced by body roll, and ensuring uneven tire wear.
  3. Suppressing minor changes in the wheelbase during suspension travel to ensure the vehicle’s straight-line stability.

The examples mentioned above represent only a small portion; others include anti-dive control during acceleration and deceleration. These complex factors related to elastokinematics, kinematics, and more are the missions accomplished through the development of multilinks suspension systems.

 Type of Multi-links Suspension

One way to classify forms of multi-links suspension is by describing the direction and quantity of control arms, treating them as a category. For example: 2 longitudinal control arms and 2 lateral control arms etc.

What are the Benefits of Multilink Suspension?

Taking the standard 5-link multi-links suspension system as an example, 4-link and 3-link configurations are not discussed here.

1. Optimizing all variables of chassis geometric

Each link is responsible for specific angles or functions, without compromising each other.

2. Reduced Unsprung Mass:

Compared to a solid axle, it has a smaller unsprung mass, allowing for lighter weight and achieving better handling, among other benefits.

3. Increased Axle Space:

Due to the independent links being freely positionable, they create more significant axle space. Conventional three-point control arms are often constrained by the body shape, resulting in cramped axle space.

4. Lower Component Stress:

Lower stress on ball joints and bushings, as they are shared among different links and bushings.

5. Great Handling and Comfort:

The multilink configuration ensures smooth wheel movement over uneven surfaces, providing improved comfort for passengers and better handling for the driver.

What are the Drawbacks of Multilink Suspension?

1. The Higher Design Costs:

If there are more links, it means that engineers need to research and develop each one individually, which translates to higher costs. Each link also requires the development of its own specific mold.

2. Poor Cabin Space:

In terms of suspension, more links indicate a need for more space, even though it liberates the axle space, it sacrifices passenger space. For example, in models like M-BENZ C,E CLASS and BMW 1,3,5 Series, the rear seat space performance is often less than ideal.

3. High Ownership Cost:

Due to the increased complexity of the system, multilink suspension comes with higher ownership costs compared to simpler suspension designs.

4. Higher Alignment Costs:

Tire alignment costs can be high with a five-link setup, as it may require individual adjustments and repeated testing of each of the five links, potentially leading to higher charges by the mechanic.

 5. Potentially Higher Repair Costs:

Having multiple links also means that if something gets damaged, individual replacements may be necessary, leading to higher repair costs.

6. Difficulties in Repairs:

Firstly, identifying which link is causing the issue can be time-consuming. Secondly, even after identifying the problem, vehicles equipped with a multilinks suspension system often have tight and less accessible repair spaces, making repairs challenging. Therefore, repair services may often demand higher labor costs.

7. Poor Lateral Rigidity:

Each link requires at least one bushing, and using bushings made of soft rubber compared to metal can result in a vague control. This leads to a sense of instability in the vehicle when cornering. However, some aftermarket brands offer spherical bearing bushings as an upgrade to improve comfort.

What Cars Have Multilink Suspension?

Multilink suspensions are often used in the rear axle because the front axle needs to allocate space for the engine compartment and the steering system, leaving no extra room for a multilink suspension system.

Vehicles equipped with a multilinks suspension system are typically designed with a focus on both handling and comfort. This results in the often vague but desirable sensation referred to as “a rigid chassis feeling.” German automotive brands, in particular, favor the use of multilinks suspensions, contributing to the characteristic feel associated with “European cars” as commonly mentioned.

Here are some examples of vehicles equipped with a multilinks suspension:

1. R/ Alfa Romeo Giulia (952)
2. R/ AUSTON MARTIN DB11
3. R/ Bentley Continental GT (MK3)
4. R/ BMW 1 SERIES (F20)
5. R/ HONDA CIVIC TYPE-R (FL5)
6. R/ Land Rover Range Rover (L460)
7. R/ LEXUS RX (MK5)
8. R/ M-BENZ S-CLASS (W223)
9. R/ Porsche 911 (991)
10. R/ Volkswagen GOLF (MK8)

From the above-mentioned vehicles, we can confirm that multilinks suspensions are often employed in high-end or sporty models. Regarding space performance, the typical outcomes include excellent spaciousness in larger vehicles where the space is not compromised, or less-than-ideal rear seat space in certain cases.

Conclusion

Simply introduce the multilink suspension system. However, as the youngest chassis system, its complexity is evident. The earliest instances of the multilink suspension can be traced back to the 1982 M-BENZ 190, making it a relatively late arrival compared to other suspension forms. In summary, despite potentially higher costs and complexity compared to other suspension types, the multilink suspension system undoubtedly provides an ideal choice for vehicles seeking enhanced handling and riding experiences.

References

  1. Roll Steer: When a vehicle experiences body roll, typically during cornering. The resulting change in load distribution causes a slight displacement of the vehicle’s four wheels compared to their normal positions, leading to steering induced by uneven lengths. While the impact of these length variations may not be substantial, they remain one of the factors that cannot be ignored in optimizing the suspension system. ↩︎