10 August 2024

How Multi-Link Suspension Works on the V.A.G MQB Platform

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General

The MQB (Modularer Querbaukasten or Modular Transverse Matrix in English) platform from the Volkswagen Group is renowned for its versatility, underpinning many models across the V.A.G brands: VW, Audi, SEAT, and Skoda.
One of the key features in the MQB platform’s is its use of multi-link suspension systems in older 4wd vehicles or in the rear of higher horsepower models.

What Goes Into The Multi-Link Suspension on the V.A.G MQB Platform

The MQB platform’s multi-link suspension includes a combination of upper and lower control arms, a trailing arm, and a toe control link.

1. Upper and Lower Control Arms: These arms control alignment through the arc of suspension travel. They are connected to the wheel hub and the subframe with bushings.
2. Trailing Arm: This arm is positioned longitudinally and helps in maintaining the wheel’s alignment during acceleration and braking. It also assists in absorbing longitudinal forces.
3. Toe Control Link: This link specifically manages the toe angle of the wheel, ensuring precise steering response and stability.
4. Anti-Roll Bar: Connected to the control arms or the subframe, it reduces body roll during cornering by transferring load between the left and right sides of the suspension.
5. Subframe: A secondary frame that provides mounting points for the suspension components. It adds rigidity and helps isolate the suspension from the main chassis, reducing noise and vibration in the cabin.
6. Bushings: Flexible (Rubber) mounts that connect the control arms to the subframe and chassis, allowing for controlled movement and damping of vibrations.
7. Shock Absorbers and Springs: These work together to absorb and dissipate energy from road impacts, controlling the movement of the wheels.

But What Are The Benefits of Multi-Link Suspension on the MQB Platform

1. Independent Wheel Movement: Each wheel in a multi-link suspension system can move independently of the others. This maintains maximum contact with the road surface, especially on uneven terrain, enhancing grip and stability.
2. Camber and Toe Adjustment: Adjustments within the links allow for precise adjustments of camber and toe angles. This adjustability helps in setting up the suspension for optimal tyre contact during cornering and braking which, improves handling and reduces tyre wear.
   1. Camber: Correct negative camber improves grip in corners by allowing the tyre’s outer edge to remain in contact with the road. The multi-link design allows for camber changes throughout the suspension’s travel, keeping your alignment when you need it most.
   2. Toe: Adjusting toe angle affects your vehicle’s response to steering input.  Multi-link systems can finely tune these angles to achieve the desired handling characteristics.

Understanding Camber & Toe: The Keys to Handling Performance

Camber refers to the angle of the wheel against a vertical point. Too much negative camber can lead to uneven tyre wear, (inner side of the tyre) whilst positive camber reduces grip. Toe, on the other hand, refers to the angle of the wheels pointing towards the centre of the vehicle. If toe is incorrect, the car will wander at the rear. Both camber and toe are crucial for optimal handling and tyre wear.

With Polybush resisting alignment changing forces, cornering and braking, you will maintain those angles. So you’ll experience consistent camber and toe settings, meaning maximum grip and minimal tyre wear.

1. Minimised Bump Steer: Bump steer happens when the toe angle of a wheel or wheels changes without any steering input from the driver. Multi-link setups are designed to minimise this effect, ensuring the vehicle maintains a straight path over bumps.
2. Isolation of Forces: The subframe and bushings isolate the suspension from the chassis, reducing the transmission of NVH (road “noise”) into the cabin. This contributes to a smoother, quieter and more comfortable drive.
3. Enhanced Handling: The independent movement of each wheel and the ability to adjust camber and toe angles ETC finely provide superior handling characteristics. This setup ensures that the tyres maintain optimal contact with the road surface, improving grip and stability during high-speed cornering.
4. Improved Comfort: The use of multiple arms and bushings allows for better isolation of road imperfections, resulting in a smoother drive. The subframe further reduces the transmission of noise and vibrations into the cabin.
5. Versatility: The multi-link suspension’s adaptability makes it suitable for a wide range of vehicles within the MQB platform, from family hatchbacks to performance-oriented models.
6. Durability: The design of multi-link suspension components enhances the system’s durability, through multiple loading points (compared to a rear axle which has 2) it is capable of withstanding the rigours of daily driving and spirited performance use.

Rubber Bushes vs. Polyurethane Bushes (More specifically, Polybush)

Bushes are crucial components in any suspension system, acting as the interface between various moving parts. They absorb shocks, reduce vibrations, and allow for a certain degree of flexibility. The two main types of bushes are rubber and polyurethane

Rubber Bushes

• Material: Typically made from natural or synthetic rubber.
• Characteristics: Rubber bushes are designed to offer a balance between flexibility and durability. They absorb a significant amount of road noise and vibrations, contributing to a comfortable ride.
• Longevity: Whilst fairly effective at dampening, rubber bushes tend to wear out relatively quickly under harsh driving conditions, road salts, and oil and fuel contamination, leading to increased play and reduced handling precision over time.

Polyurethane Bushes (Polybush)

• Material: Made from a synthetic polymer known for its durability and strength.
• Characteristics: Polyurethane bushes are much more resistant to deformation than rubber, providing less deflection in the same hardness rubber. This resistance translates to more precise handling and a more direct connection between the suspension components and the chassis.
• Longevity: Polybushes are significantly more durable than rubber bushes, maintaining their performance characteristics over a longer period and in more demanding conditions.

Benefits of Installing Polybush on the MQB Platform

1. Enhanced Handling: Polybushes reduces unwanted movement in the suspension components, leading to more precise handling. This is particularly beneficial for performance-oriented drivers who value sharp and responsive steering but as Polybush can be made in any hardness, it is still true for more “normal” vehicles.
2. Improved Stability: By maintaining consistent alignment settings, Polybushes help ensure that camber and toe angles remain within optimal ranges, even under heavy cornering or braking. This stability is crucial for maintaining grip and preventing unpredictable behaviour.
3. Longevity and Reliability: Polybush products are significantly more resistant to wear and degradation caused by environmental factors such as oil & fuel, UV light, and temperature changes. This durability means less frequent replacements and a more consistent performance over time.

1. Feedback and Control: For those who enjoy spirited driving, the more direct feedback provided by Polybush can be a revelation. The improved connection between the driver, vehicle, and road enhances the driving experience, making the car feel more predictable and controllable.

Conclusion

The multi-link suspension on the MQB VAG platform is a sophisticated system designed to offer a balance of comfort and performance. Understanding the role of camber and toe in this context helps appreciate how suspension tuning affects vehicle dynamics. While rubber bushes are adequate for many drivers, those seeking enhanced handling, stability, and longevity should consider upgrading to Polybush. Our material provides a more direct and responsive driving experience, making it a worthwhile investment for anyone looking to get the most out of their MQB-based vehicle.

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