There are a huge number of different cars in the world. 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 the comfort of movement. At the moment, there are different suspension schemes. And today we will consider one of the simplest categories. This is a semi-independent suspension. Its key component mechanism is the rear beam. What is it and how does it work?
So what is a rear beam? This is one of the main components of the torsion bar suspension, which connects the wheels to the body at the rear of the car. There are longitudinal levers as guide mechanisms. The latter are rigidly interconnected by a beam. On the one hand, the trailing arm is attached to the hub, on the other - to the car body. The rear beam of the VAZ and other budget cars has a U-shaped section. As a result, it has low torsional rigidity andbig on the bend. This characteristic allows the wheels to move up and down independently of each other.
This node will consist of several elements:
- Rubber-metal hinges (usually there are only two of them) that are attached to the side members of the body.
- Helical springs.
- Wheel hubs.
- Trailing arms.
- Shock absorbers.
- Directly torsion beam.
The device is quite simple, which is why this suspension scheme is quite popular.
Is there a stabilizer?
Almost every car in the front suspension has such a device. This is an anti-roll bar. However, is it present at the back? Unfortunately, there is no such device in its usual form. Instead, an elastic metal rod can be used, which is located inside the beam itself. A similar design is used on Daewoo-Nexia, Daewoo-Lanos and others (a photo of this beam is present in the article below).
This element plays the role of a kind of stabilizer, which allows you to reduce roll when turning the car. But, as practice shows, it still doesn’t work to achieve such controllability as on a car with a multi-link suspension.
Where does it apply?
This 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, hercalled semi-dependent. Although the wheels can move differently, you can’t expect the same results as with multi-link suspension here either.
There are several advantages of using this beam in the rear suspension of a car:
- Compact. The beam does not require a lot of space, and therefore can be used in a wide variety of cars, including many small cars.
- Light weight. This is another plus in favor of using a beam on cars A and B class.
- High maintainability. Due to the simple device, there is practically nothing to break here. The beam is quite reliable and can go out and down only in extreme cases. The only thing that is required during operation is to change consumables on time. We will talk about replacing them a little later.
Now for the downsides. There are only a few of them, but they are significant:
- Firstly, the rear beam does not provide such a smooth ride as a multi-link suspension. The wheel travel will still be limited, since both parts are connected, albeit with an elastic, but metal structure. Therefore, such a suspension scheme is not practiced on cars of class C and above. No semi-independent beam will provide such a smooth ride as a simple independent suspension. Also note that the wheels can only move in one direction (up and down). In the case of a multi-link suspension, they change their angle of inclination when they enter the pit.
- Secondly, the controllability of the car is significantly reduced. Often on such machinescornering blows the rear axle. This is acceptable for the budget class, but unacceptable for more expensive cars, especially with powerful engines. At the very least, it's unsafe. Therefore, the rear beam is used mainly on cars with engines of no more than one and a half liters.
Let's take a look at what problems owners of cars with a rear beam may face:
- Shock absorbers. Their resource as a whole is no less than on multi-link suspensions. However, if we take the beam structure as a whole, this part always wears out before the others.
- Wheel bearings. If we talk about the Peugeot 206 rear beam, the owners have to change these bearings on average once every 100 thousand kilometers. It is recommended to replace both bearings at once, since their life is approximately the same.
- Silentblocks. Unlike multi-link suspension, they go much longer. There are many examples of how silent blocks of the Renault rear beam served for 150-200 thousand kilometers. In the case of a multi-link, 150 thousand is the deadline.
- Springs. They sag over time, but not significantly. Before replacing them, owners have to change the rubber gaskets. Due to the frequent work of the turns, they are wiped.
Does the entire rear beam need to be replaced? We can say that this design is eternal and lives as long as the car itself. A complete replacement of the beam is needed only in the event of a serious accident, when the geometry of the body was violated. Ifthe machine was operated without serious accidents, the owner can only replace consumables (shock absorbers, silent blocks and wheel bearings).
Is there a rear beam tuning? Unlike the front suspension, car owners do not bother much with its refinement. However, there is still a way to improve the characteristics of this device. The most common tuning option is the installation of an anti-roll bar. We have already talked about the absence of such an element and the excessive sluggishness of cars. Installing this device additionally allows you to reduce lateral roll and improve the controllability of the machine. How 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 bolts of the device, and in some cases it wraps around the beam itself in the center. 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 a 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 turn better. However, you need to understand that after such tuning, allthe load will go to one side of the tread. In this case, the resource of tires is reduced by half.
So, we have considered what the rear beam is. Despite its archaism, almost all budget cars are produced with such a suspension scheme. This is due to the cheapness of production, as well as a decrease in maintenance costs.