In the world there are a huge number of different cars. All of them have their own characteristics, including in terms of the chassis. Suspension is a complex set of mechanisms that allows you to ensure the stability of the car on the road and comfort of movement. At the moment, there are different suspension schemes. And today we look at one of the simplest categories. This is a semi-independent suspension. Its key component is the rear beam. What is it and how is it arranged?
Description
So what is a rear beam? This is one of the main components of the torsion bar suspension, which provides the connection of the wheels with the body at the rear of the car. As guiding mechanisms, there are longitudinal levers. The latter are rigidly interconnected by a beam. On the one hand, the trailing arm is attached to the hub, and on the other, to the car body. The rear beam of the VAZ and other budget cars has a U-shaped section. Due to this, it has low torsional rigidity and large bending. This characteristic allows the wheels to move up and down independently of each other.
Device
This node will build from several elements:
- Rubber-metal hinges (as a rule, there are only two of them) that are attached to the side members of the body.
- Coil springs.
- Wheel hubs.
- Trailing arms.
- Shock absorbers.
- Directly torsion beam.
The device is quite simple, which is why such a suspension scheme is quite popular.
Is a stabilizer present?
Almost every car in the front suspension has such a device. It is a stabilizer bar. However, is he present from behind? Unfortunately, such a device is absent in our usual form. Instead, an elastic metal rod that is located inside the beam itself can be used. A similar design is used on cars "Daewoo-Nexia", "Daewoo-Lanos" and others (a photo of this beam is presented in the article below).
This element plays the role of a kind of stabilizer, which allows you to reduce rolls when cornering the car. But, as practice shows, to achieve such controllability as on a car with multi-link suspension, it still does not work.
Where does it apply?
Such a beam is used only on front-wheel drive cars of a budget (sometimes middle) class. Due to its unique design, this suspension occupies a position between independent and dependent. Therefore, it is commonly called semi-dependent. Although the wheels can go in different ways, one does not have to expect such results as with multi-link suspension.
Benefits
There are several advantages of using this beam in the rear suspension of a car:
- Compactness. The beam does not require a large space, and therefore can be used in a variety of cars, including many small cars.
- Light weight. This is another plus in favor of using the beam on A and B class cars.
- High maintainability. Due to the simple device, there is practically nothing to break here. The beam is quite reliable and can go out and build only in extreme cases. The only thing required during operation is to change consumables on time. We will talk about replacing them a little later.
Now about the shortcomings. There are only a few, but they are significant:
- Firstly, the rear beam does not provide such softness as a multi-link suspension. Wheel travel will still be limited, since both parts are connected, albeit with an elastic, but metal structure. Therefore, this suspension scheme is not practiced on cars of class C and above. No semi-independent beam will provide such smoothness as a simple independent suspension. Also note that the wheels can only go in one direction (up and down). In the case of multi-link suspension, when they fall into the pit, they change their angle of inclination.
- Secondly, the controllability of the car is significantly reduced. Often on such cars cornering blows the rear axle. This is acceptable for a budget class, but unacceptable for more expensive cars, especially with powerful engines. At a minimum, this is unsafe. Therefore, the rear beam is used mainly on machines with engines of no more than one and a half liters.
Major malfunctions
Consider what kind of malfunctions car owners with a rear beam may encounter:
- Shock absorbers. Their resource as a whole is no less than that on multi-link suspensions. However, if we take the design of the beam as a whole, this part always wears out before the rest.
- Wheel bearings. If we talk about the rear beam "Peugeot-206", the owners have to change these bearings on average once every 100 thousand kilometers. It is recommended to replace both bearings at once, as their service life is approximately the same.
- Silent blocks. Unlike multi-link suspension, they go much longer. There are many examples of how the silent blocks of the rear beam of the Renault served 150-200 thousand kilometers. In the case of a multi-link, 150 thousand is the deadline.
- Springs They subside over time, but not significantly. Before replacing them, the owners have to change the rubber gaskets. They are wiped due to the frequent operation of the turns.
Is the entire rear beam required? We can say that this design is eternal and lives as long as the car itself. A complete replacement of the beam is needed except in the case of a serious accident, when the geometry of the body was violated. If the machine was operated without serious accidents, the owner can limit himself only to replacing consumables (shock absorbers, bushings and wheel bearings).
Tuning
Is there a rear beam tuning? Unlike the front suspension, car owners do not bother much about its refinement. However, there is still a way to improve the performance of this device. The most common tuning option is the installation of a stabilizer bar. Earlier, we talked about the lack of such an element and the excessive slowness of cars. Installing this device in addition allows you to reduce lateral roll and improve the handling of the machine. What a similar element looks like, the reader can see in the photo below.
To install such a stabilizer, you do not need to make additional holes or weld anything. The mechanism is fixed to the standard mounting bolts of the device, and in some cases in the center it surrounds the beam itself. Thus, the design gives additional rigidity without sacrificing comfort. At the moment, there are ready-made kits for installation on front-wheel drive cars of the VAZ brand.
Another type of tuning is the installation of metal plates under the hub. This is done in order to obtain negative camber. As a rule, this is necessary when installing wide disks in case they do not fit in the arch. Negative camber will improve the handling of the car. The car will be better off entering turns. However, you need to understand that after such tuning the entire load will go to one side of the tread. The tire resource is reduced by half.
Conclusion
So, we examined what the rear beam is. Despite its archaic nature, almost all budget cars are produced with such a suspension scheme. This is due to the low cost of production, as well as a decrease in maintenance costs.