2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42
Silent blocks are car parts responsible for connecting certain components and elements of mechanisms. They are installed both in the front and rear suspension and are used to connect the suspension elements and fasten the levers, fix the car engine and gearbox. There are several varieties of silent blocks, but the most commonly used silent block is floating.
Silentblock design
The silent block is a hinge, the design of which consists of metal bushings and a gasket located between them. Such an insert is made of polyurethane or rubber and dampens vibrations transmitted from one mechanism to another.
Floating silent blocks device
Floating silent block is a ball-type joint. Together with other silent blocks and shock absorbers, it is responsible for providing the vehicle's speed advantages, acceleration and braking dynamics, and handling.
Unlike other similar parts, ball joints provide a movable and reliable connection of levers, suspension mounts and wheelsvehicle, thanks to which they can move in different directions in certain planes, including vertical ones. The floating silent block provides a movable connection between the wheel strut and the suspension arms, which makes it possible to turn the front wheels and respond to vertical vibrations of the spring.
Types of construction of silent blocks
Ball joints for cars are produced in several variations. The first model consists of a housing, in the hole of which a ball pin with a spherical head is installed, a liner made of composite material and a spring that presses the liner. The hole in the housing is through, its walls consist of conical and cylindrical surfaces. Conical sections are located on the outer surface of the liner at an equal distance from each other. They interact with the annular compression spring and the equidistant surface of the housing. A cover is installed in the housing that presses the spring, and the spring element itself includes a spring and a support section.
Cons of silent block design
The floating rear silent block, which has the design described above, has disadvantages - the high cost of the spring element and too complicated execution. Taking into account the most important characteristics for such a part, its closest analogue is a ball joint, consisting of a body, a ball pin, a clamping sleeve and an insert. The sleeve, unlike the spring, is made of polymer material.
The disadvantage of this design is the complex and time-consuming production process. For the manufacture ofhinges capable of crimping the entire body on the tail side of the pin require special equipment.
Analysis of all existing designs of ball joints allows us to draw the following conclusions:
- Features of such parts depend on the year of manufacture and manufacturer.
- Floating silent blocks develop as the material and design features of the liners change - from elements made of metal to Teflon parts closed with a plastic clip.
- The number of silent blocks parts has decreased in recent years from 12 to 6. This was achieved by eliminating the elements that were responsible for lubricating and adjusting the ball joint during the operation of the car.
- All ball bearings require reliable and high-quality protection of rubbing surfaces from contamination. Special covers for supports - anthers - are distinguished by a short service life due to rapid wear and tear. To reduce wear and friction, they try to use liners with Teflon jackets in plastic cases. The reliability of the hinges is also improved by increasing the roughness of the surface of the fingers.
The principle of operation of floating silent blocks
Under normal and medium loads, the floating silent block behaves like a normal hinge, but with an increase in the degree of impact, its resistance to strong impacts increases, but does not harm the rubber band. A similar result is achieved due to the fact that there is a liquid inside the part, which is why the hinge was givenfloating name.
During the movement of the car, all its nodes connected by silent blocks also come into motion. This causes an angular displacement of the ball pin relative to the housing. The force is transmitted from the hinge body to the pin through the bushing, head wear is compensated by the spring.
The inner surface of the liner has a large diameter, which reduces the load on the surface of the head and guarantees a high level of wear resistance of the structure as a whole. The polymer liner, before proceeding with the assembly of the hinge, is pressed onto the liner. The floating rear silent block, especially its metal parts, is coated with a special protective compound that protects against corrosion.
How silent blocks are attached
The hinges are installed in the suspension arms in several ways. The most common, which is used to mount the KIA Sid floating silent block, is to press the part together with the outer sleeve into the lever eye. It is attached to it due to the force of friction. This design dampens vibrations and various loads. It is repaired simply and easily: the old silent block is knocked out with a sledgehammer or hammer, and a new one is installed in its place.
If the lever is loaded in one direction or plane, or it itself acts as a guide, then the silent block does without an external bushing. In such a situation, hinges are used, at the end of the elastic elements of which there are beads. With the help of the latter, it is pressed into the eye.
Recently, integrated silent blocks have become very popular, in which the role of the outer sleeve is played by the eye of the lever, inside which an elastic element is pressed. Similar elements can be found in the latest models of Toyota cars - floating silent blocks on such machines are integrated. Such a design does not have a special engineering meaning: its main task is to increase profits for the manufacturer, since it is almost impossible to press new rubber into the lever outside the factory conditions. In this case, you will have to make a complete replacement of the lever, which costs a very large amount.
Rubber or polyurethane?
For almost all models of silent blocks, the elastic element is made of rubber. The greater the content of this material in the composition, the better the characteristics of the hinges. Despite this, they also have their own counterparts that are not inferior in quality.
Non-original silent blocks are most often made of synthetic polyurethane and are very popular with car owners who want to save on original car parts.
The huge advantage of this material is its long service life. Polyurethane silent blocks can be used for several years.
Despite this advantage, polyurethane silents have no special advantages. Many of them do not undergo a vulcanization reaction, respectively, to securely attach their elastic part tometal is impossible, and it is impossible to compress such material: it is too hard. Hinges made of low-quality polyurethane quickly fail - after 40-50 thousand kilometers. The reason for this is the detachment of the elastic material from the surface of the sleeve.
Even if the composition of the silent block is chosen correctly, the main problem remains rigidity. After installing a polyurethane silent block, the smoothness of the car's running decreases, the elastokinematics of the suspension is disturbed - the nature of the location of the wheels under the influence of lateral and longitudinal forces. Simply put, it can eliminate the rear-suspension thruster that is common with many modern cars.
Silentblock service life
Properly installed high quality silent blocks, even under adverse operating conditions, are able to work for a long time. On average, the period of their operation is from 70 to 150 thousand kilometers.
Terms of operation and the difference in them directly depend on the quality of the product. Cheap models made of poor materials cannot cope with serious loads and quickly fail. For example, Mercedes floating silent blocks are of high quality and long service life.
Active operation of the car in bad road conditions - driving off-road or dirt tracks can contribute to the rapid wear of silent blocks.
Malfunctions of silent blocks
Active operation of the car on bad roads, as mentioned above, canadversely affect the condition of the suspension. Too high loads primarily affect silent blocks.
The maximum load falls on the suspension rods and parts of the levers. For preventive purposes, it is desirable to diagnose silent blocks every 50 thousand kilometers. Such a procedure will allow you to determine malfunctions in advance and understand whether replacement of floating silent blocks is required.
If the car has not been diagnosed for a long time, the wear of certain parts may adversely affect the handling and safety of the vehicle.
The main signs that the floating silent block is faulty are:
- The car veers from side to side while driving or only moves in one direction.
- Tire side wear.
- When braking, the car loses directional stability.
- The body vibrates while driving.
- Visual inspection of silent blocks reveals violations of their integrity.
- Suspension squeaks while driving.
- The stiffness of the suspension increases.
Each of the listed signs, like all together, indicates possible malfunctions in the operation of the hinges. In such a situation, it is advisable not to continue driving the car. Replacing floating silent blocks will help to cope with malfunctions.
How to replace the floating silent block
Depending on the brand and model of the car, the process of replacing the hinge may be different and have its own characteristics. However, for almost all vehicles, replacementrear floating silent blocks has common features.
The process of replacing the silent block
First, the handbrake is loosened on the car and the wheel is removed. The pads are brought together, after which the brake caliper is unscrewed, and the pads themselves are removed. The mounting bolts are unscrewed: from the transverse arm, brake caliper, stabilizer bar and shock absorber. The last moment is to remove the brake disc and unscrew the body bolts from the ABS sensor.
The cotter pin is pulled out, after which the breakaway lever nut is unscrewed, the bolt of the hinge itself is loosened, and the trailing arm fastening bolts are unscrewed. As a result, only the hub remains without attachments. Its mounting bolts are also removed, as are the bolts of the handbrake mechanism. There should be only a lever and a floating silent block ("Mark-2" or another car - it doesn't matter), attached to the wire from the sensor.
The boot is removed from the oil seal on the side of the rear bumper, behind which a detachable clip is hidden. It is removed from the seat using a 6-8 mm drill. After that, the lever is turned over, and the silent block ball is removed from it along with the bushing. Its clip is knocked out with a mallet or a special puller.
The new hinge is thoroughly lubricated and then installed. Pressing can be done using the same mandrel that was used to remove the old part, or you can resort to a portable vice. After installing a new silent block, all parts are assembled in reversesequences. It is advisable to check the shock absorbers, camber arms and other suspension elements for wear after replacement.
The final tightening of the suspension elements is made only after the car is removed from the pit or jack and lowered to the ground.
Features of replacing silent blocks on different makes and models of cars
The process of replacing hinges may vary and have specific features depending on the specific make and model of the vehicle on which the entire installation procedure of the part is carried out. For example, a BMW floating silent block will require the owner to visit a turner before replacement - the rear fists of such cars are aluminum, not cast iron, so they need a special puller. Original pullers are expensive, so it will be more profitable to have them made by craftsmen.
Many car models require the installation of only original spare parts. Of course, you can install non-original silent blocks, but this is fraught with their rapid wear and loss of warranty.
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