First, let me show you a picture so you can see how many bushings are used in the suspension.

Have any of you ever wondered why suspension systems are designed with so many bushings?

The quality of the bushings determines the overall performance of the vehicle!

The reason why suspension systems are designed with a large number of bushings is not simply ‘for the sake of complexity’, but rather the result of a balance struck between various factors, including performance, NVH, durability, cost and tuning.

The key reasons can be summarised as follows:

1. Performance Requirements

The bushings provide a ‘soft connection’, balancing handling and comfort.

The suspension is connected to the body via bushings, which help to reduce the impact and vibration transmitted to the body; at the same time, they ensure the vehicle’s handling stability and maintain the suspension’s elastic kinematic characteristics.

The bushings provide controlled stiffness across all six degrees of freedom for components such as the control arms and subframe: they are soft in the axial direction, stiff in the radial direction, and adjustable in torsion. This not only ensures the stability of the wheel alignment parameters whilst driving, but also utilises the slight deformation of the rubber bushings to absorb minor impacts, thereby delivering the comfort associated with a ‘soft connection’.

2. NVH requirements

Interrupt the vibration transmission path to reduce NVH.

Road vibrations are transmitted to the body via the springs and shock absorbers on the one hand, and via the suspension links and subframe on the other. Rubber bushings isolate high-frequency, low-amplitude vibrations in the middle section of this path, reducing cabin noise by approximately 3 dB.

3. Durability requirements

The bushings protect associated components and enhance the vehicle’s overall durability.

The bushings first absorb part of the impact energy, reducing the bending load on the shock absorber piston rod by 15–25 per cent and multiplying the fatigue life of ball joints, steering gear and body welds; if the bushings were removed, these components would soon develop oil leaks, cracks or abnormal noises.

4. Cost requirements

Deformation of the bushing can compensate for manufacturing and assembly tolerances, thereby reducing processing costs.

The bushings allow for a tolerance of ±1–2 mm during the welding of sheet metal components such as the subframe and control arms; the rubber deforms to ‘absorb’ any errors, thereby avoiding the need for expensive metal hinges or adjustable mechanisms, which can reduce the overall vehicle cost by several hundred yuan.

5. Training requirements

The bushings allow for multi-directional stiffness adjustment, providing flexibility in chassis tuning.

For example, with the same set of chassis bushings, simply changing the rubber compound can adjust the lateral stiffness from 400 N/mm to 800 N/mm without the need to redesign the bodywork. For the vehicle as a whole, this means that a single platform can be configured to deliver a variety of driving styles, such as a ‘comfort’ version and a ‘sport’ version.

Summary:
‘Multiple bushings’ are not redundant; rather, they utilise compact, low-cost, multifunctional rubber elastic components to simultaneously address the five key requirements of performance, NVH, durability, cost and tuning. It can be said that the quality of the bushings determines the overall quality of the vehicle.