Even more comfortable, still safer.


Automotive suspension is a dynamic system directly affecting safety and comfort when operating a vehicle. The technical condition of this system determines the behavior of the car in various conditions of movement, especially this applies to parameters such as the braking path, the grip of the wheels with the road, acceleration, or follow the curvilinear trajectory when driving along various coatings. Therefore, special attention is paid to the development of technologies of automotive suspension.

Evolutionary way

To meet all the higher requirements of the suspension of modern cars, in fact turned into extremely complex mechatronic units, allowing to change the parameters of vibration-insulating systems. Executive elements allow you to adjust the parameters associated, for example, with rigidity, in a specific range of parameters.

Therefore, there is a continuous evolution of semi -active, active and adaptive suspension systems. Unlike passive suspension systems, all the above types allow you to adapt the suspension parameters to individual road conditions and driving styles. The suspension control systems regulate the characteristics of the elastic and damping components in accordance with the predetermined criteria, such as a comfortable or sporty driving mode, for example.

The use of various constructive solutions to the suspension affects many significant parameters, one of which is the frequency of free oscillations of the system. For a system with a classic passive mechanical suspension (spring), the frequency of free oscillations of the system is reduced as the load increases. In the pneumatic suspension systems, the frequency is also reduced by increasing the load in the system, but not as much as in the classical one.

Eliminate shortcomings

In mechanical suspensions, with an increase in the load, the static compression of the elastic element increases, whereas at full load the range of the permissible wheel of the wheel on the compression decreases, which is one of the most significant disadvantages of such systems. Therefore, in spring type suspension systems, progressive characteristics are usually required, which are achieved due to the corresponding structural solutions (two parallel springs, etc.).

In order to be able to manage and generate strength in the system, it is necessary to apply complex control algorithms (management principles, such as, for example, SkyHook, which optimize damping parameters in accordance with the criterion for reducing speed for spring mass). The restriction of these solutions is to delay in time (inertia) of the executive elements of the mechatronic system.

Among the most advanced solutions used in the active suspension systems, MPCD (Model Predictive Controller) should be selected, the control algorithm that uses information about the road profile — special sensors allow you to identify the road profile in front of the car. This information allows you to calculate and optimize the settings of the chassis.

Wealth decisions

Controlled solutions are usually based on mechatronic systems that use shock absorbers with variable characteristics. Moreover, this does not always lead to a significant increase in the complexity of the mechanical suspension system (shock absorber, spring and suspension levers). But undoubtedly leads to the introduction of additional electronic systems.

Automakers choose different suspension designs, preferred the most efficient and suitable solutions for specific operating conditions. But regardless of whether it is a mechanical, hydraulic or pneumatic suspension, the control of it is increasingly carried out by electronics. Only in this way, you can provide a full control of the settings of the chassis of the car, affecting them during the movement of real-time.

Here are some examples of such solutions:

• CDC (Continuous Damping Control), also known as Skyhook or IDS and used in cars such as WV, BMW, GM, Opel, Fiat, Porsche, Ferrari, Maserati. This solution is based on an electronic system of adjustable oscillation damping by shock absorbers with two electromagnetic valves (providing separate compression and penal control). ADS systems are working on a similar principle (Adaptive Damping Control — Mercedes-Benz is used in models as S, E, CLS and SL, CL, SLK), CES (continuously controlled electronic suspension, also known as Four-C and used in Volvo S60R / V70R and S80).

• The Magnetride system is a solution that is commonly referred to as magnetic motion control and used in vehicles manufactured by GM Corporation as well as in Chevrolet Corvette. It is based on the use of the properties of the magnetoreological fluid. Under the influence of the magnetic field, the system adapts its physical properties, which allows you to adjust the shock absorber damping parameters for less than 1 millisecond. Instead of the electromagnetic valve, this solution has a set of channels of the corresponding diameter used to supply the magnetoreological fluid. The operation of the shock absorber does not represent difficulties, since the relationship between the damping force and the magnitude of the current strength generating the magnetic field is actually linear. The range of changes is quite wide, which allows you to generate strength, 14 times higher than that which is generated under zero power supply conditions.

• DRC (Dynamic Ride Control) — a solution used in AUDI RS6 Quattro. It is based on hydraulic bond between the shock absorbers of individual wheels and valves that control the fluid flow.

• PDC shock absorbers (PNEUMATIC Damping Control) used in Audi Allroad. In this system, the parameters of the springs of the pneumatic suspension adjust the parameters of the corresponding shock absorber characteristics. Air pressure in the suspension spring adjusts the settings of the special PDC valve installed in the shock absorber.

There are also more extended systems that use solutions based on pneumatic or hydraulic systems. Moreover, in the latter with the pneumobalon, the constant mass of gas, the road clearance is regulated by increasing the amount of fluid in the hydraulic cylinders. However, whatever modern suspension systems, it is obvious that the use of non-traditional structures requires the development and improvement of the diagnostic methods used in assessing their technical condition.


Such a complication of constructs of contemporary car suspension leads to the fact that only the method based on vibration tests with harmonic kinematic excitation can be the only effective method of assessing their technical condition. And only on a specialized booth capable of reproducing the necessary test cycle in a wide range of parameters under study.

The old good organoleptic method, still actively used on a multitude of Russian serviceive, irrevocably loses its objectivity, yielding the place to progressive electronic algorithms. The only thing for which it can still be used is only for visual assessment of the integrity of the components and the absence of their damage.

Sergei Chumakov:

Diagnosing and servicing complex systems of suspension of modern cars, one hundred employees should use an integrated approach, comprehensively checking the state of nodes and aggregates. You should not be afraid when replacing shock absorbers to offer a replacement and, for example, springs, because only in this way you can ensure the restoration of the technical characteristics of the chassis to the level as close as possible to the original configuration. Moreover, it is necessary to change the springs only in pairwise, using special equipment, without which the installation of the screw spring is dangerous and can damage the springs itself.

Well, so that mechanics are not mistaken during the work process, Lesjofors offers a large set of educational events, which is regularly conducted by our specialists, trainings, seminars and webinars, and so on. We are always ready to answer any questions and provide all the necessary information. And most importantly — ensure continuous service from the date of delivery of products

Well, in the future, of course, the diagnosis will be more complicated even more, so now the development of appropriate techniques is aimed at obtaining additional diagnostic information (not only the amplitudes of oscillations in resonance), such as, for example, the phase angle and the unique association of this information with the distribution of the mass of transport means (ratio of spring-loaded and unsophisticated masses).

Well, in the future, of course, the diagnosis will be more complicated even more, so now the development of appropriate techniques is aimed at obtaining additional diagnostic information (not only the amplitudes of oscillations in resonance), such as, for example, the phase angle and the unique association of this information with the distribution of the mass of transport means (ratio of spring-loaded and unsophisticated masses).

Diagnosis of steering wheel vibration

Worn, faulty or unbalanced steering component or suspension can be felt through the steering wheel vibration or as oscillation, shaking or shaking. However, the reason for this may be the problems of many details — the search for the source can become laborious even for the most experienced mechanics. Therefore, we introduce you to the main reasons, the symptoms and methods of correctness of problems that will help you optimize the repair work.

Sibalance kers

The weight distribution in each bus varies slightly. But to compensate for it, additional loads must be added after installing the new tire on the wheel. Unfortunately, these goods can sometimes move or lean, which leads to an imbalance of wheels. Even in good conditions, unbalanced tires can cause a shaking (vibration) of the car when driving at high speeds, starting approximately from 80-90 km / h, often the most noticeable at a speed of about 100 km / h. If you do not pay attention to this, unbalanced wheels can wear steering, tires and suspension parts faster than usual, and cause fuel overrun when the car is moving.


Another common cause of the steering wheel vibration is the wrong set of corners of the wheels. In most cases, the correction will eliminate the vibration, which will be a guarantee that all the wheels are installed correctly. One of the fastest ways to diagnose the corners is to check the tire tread. The car with the problems of installing the wheels often has uneven tire wear, for example, the inner or outer part of the tread is different in different ways. If you notice that the steering wheel is right, and the car still pulls into some direction, then, most likely, the problem is not eliminated.

Damaged or worn bearing wheels

If the steering wheel vibrates only during turn, then the next part, whose work you should check whether the wheel bearing can be the wheel bearing. Designed for fastening the wheel hub to the car suspension and ensuring the rotation of the wheels, very important components for safety can cause the steering wheel vibration if they are damaged or not tightened. Bearings of wheels can be worn under regular motion over uneven roads or damaged when a collision at high speeds with potholes, artificial irregularities («lying police») or borders. Changes in steering systems and / or suspension can also lead to unnecessary wheel bearing wear. Other signs of the worn bearing, in addition to the fighting of the steering wheel, there may be abnormal noise emanating from the damaged wheels that become louder at speeds, vague steering and / or damaged ABS sensor.

Worn steering or suspension parts

It takes only a small backlash or attenuation in any of the steering components and the suspension so that the entire system becomes slow. In addition to the impact on the control and stability of the car, it can also cause the steering wheel vibration. Therefore, it is very important to check the system for the presence and must be replaced. Similarly, loose shock absorbers, damaged or disconnected springs and flowing shock absorbers or racks can cause the steering wheel vibration. They must be checked and replaced as needed.

Problems with brakes

If the steering wheel vibrates only when stopping and / or the brake pedal is also shaking, then, most likely, the problem is in the brake system. The vibration of the steering wheel can also be caused by braking due to a mechanical or hydraulic fault or fault of the parking brake. Frequently called brake shiver, vibration when braking can be caused by brake disc warping, change the disk thickness (DTV) and / or strong overheating and disk curvature

Brake discing

The vibration of the steering wheel can be caused by an incorrectly installed brake disc, which is not parallel with the hub or caliper. The reasons for a bad installation range from rust or mud accumulation between the disk and the hub, creating an uneven surface, to excessively twisted positioning screws and / or installation of the disk to the deformed hub. Although the deformed hub is rarely found, in recent years there is an increase in the use of wheeled spacers, which can cause excess wear of the hub.