What is a silent block? This is a rubber-metal hinge, through which the suspension arms of the car are attached to it (for example, to the body or front suspension beam). During operation (even during parking in the garage) of the car, the latter are exposed to forces. The direction of which is almost constant. This leads initially to elastic deformation. Elastic - this is a type of deformation, when in the event of the termination of the action of forces, torques, it is eliminated, the deformed parts return to their previous state that preceded it. However, if the silent blocks have already worked for some time and / or are poorly made, their deformation may become inelastic. This is its kind when, after the removal of external influences, the parts do NOT completely or do not return to their original position at all, i.e. permanent deformation appears.
An example from "life", so to speak. Take a piece of wire, try bending it a little. While the bend is weak, as soon as you release the bending end, it will immediately return to its original position (this is an example of elastic deformation). If you try to bend further, then the wire will remain in a bent state, or even break off. This is already an inelastic deformation. True, if the wire has springy properties, it will be possible to bend it quite strongly - until the moment when residual deformation appears. But nonetheless.
Rubber is an elastic material (to a certain extent, of course), and the degree of its elastic deformation is very high: due to the so-called high elasticity inherent in polymers, which include rubber, the degree of their relative elastic deformation can reach several hundred percent, up to 1000% and even more. For metals, not to mention ceramics, glass, it is much lower. That is why silent blocks are made with rubber inserts: at present, no other material is known on earth that has such a high degree of elastic deformation. True, single-crystal metals, as well as gases and liquids, are worth a separate discussion, but we will not discuss them here.
However, during operation, under the influence of external forces, as well as under the influence of other factors (for example, such a factor can be ultraviolet radiation coming from the sun), the internal structure of rubber (as, in other matters, of any polymer) begins to "deteriorate" . More specifically, imperceptible microcracks and pores begin to appear in it. Although, the manufacturing technology of any polymer is such that they are present in it in one quantity or another directly, as they say, "from birth". They just increase in number and size over time.
Sooner or later, this leads to the fact that a high degree of elastic deformation of the polymer (rubber) becomes unattainable: it begins to break, such cracks appear that are clearly visible to the naked eye - and it is then that the silent blocks are rejected, concluding that they are faulty . The latter begin to crack, crumble into pieces, bulge. The presence of such manifestations is a signal for the replacement of silent blocks.
Before that, they may experience an intermediate state, just characterized by residual deformation. It manifests itself in the fact that the inner part of the silent block is inelastically displaced in one direction or another relative to its outer part and remains in this position even when external influences are removed or if they do not exceed a certain value. Let us explain the above with schematic drawings - using the example of a silent block of the upper arm of the front suspension of a car.
The figure shows a serviceable silent block. There are no cracks or pores, there are no gaps between the rubber insert and bushings. External influences can cause displacement of the inner part of the silent block relative to the outer one, but when they are removed, everything returns to its original position.
During operation, cracks begin to appear in the rubber bushing of the silent block. Initially small, but then gradually increasing in size. 
As cracks appear and also as a result of fatigue ( by the way, the term "fatigue" is quite technical, here it is not used in the form of a common expression; materials, like people, also get tired, which leads to a decrease in their performance) rubber, its ability to withstand external forces is reduced, it becomes more susceptible to inelastic deformation. As a result, the inner part of the silent block moves to the side and remains in this position, even if external forces are removed. That is, permanent deformation occurs.
When the value of such a displacement begins to exceed the limit set for a particular brand of car by the manufacturer, the silent blocks are rejected. It is clear that what less quality was the manufacture of the silent block, how more aggressive driving style, how stronger the front wheel alignment angles differ from the optimal values the sooner this situation will come.
What does this lead to in relation to the behavior of the car on the road?
Let's say the front wheel of the car hit an obstacle - a stone or hit a rut, etc. Or the driver makes a maneuver, brakes or something. If the car is moving at low speed, so that the force acting on the wheel from the side of the obstacle is not enough to cause the inner part of the silent block to move to the other side, the car will continue to go on as if nothing had happened, except by bouncing.
If the force exceeds the critical one, then the direction of residual deformation will be different, as shown schematically in the figure. 
Accordingly, this will lead to a change in the installation angles of this front wheel. Which, naturally, will cause a violation in the trajectory of the car. Those. the latter becomes dangerous in operation, prone to uncontrolled changes in the direction of its movement, now and then "prowls" along the course.
Characteristically, such a shift will be uncontrolled, random. And therefore - difficult to diagnose. If at the same time try to do (i.e., setting the angles of the front wheels), its results will not be too satisfactory. As in the case when the ball joints are faulty.
So what is next?
Finally, if you continue to operate it further without repairing the front suspension, the number and size of cracks in the rubber liner become even larger. As a result, the silent block, firstly, begins to collapse, and, secondly, its tendency to inelastic deformation increases. As a result, a gap appears.
It is clear that in this state of the silent block it is necessary to replace it immediately. For in the future, the rubber liner will quickly break, the inner part of the silent block will touch its outer part (the one that is pressed into the front suspension arm). When driving, a clear knock will be heard, especially when hitting bumps in the road.
Silent blocks are one of the important elements of car suspension. These hinges, consisting of two metal bushings and a polyurethane or rubber gasket between them, are installed on both the front and rear axles and serve to connect other elements. In addition to this, the elastic gasket of the silent block allows you to dampen all kinds of vibrations and shocks that occur during the movement of the car. Since a fairly significant load is constantly placed on these hinges, the quality of these hinges and their technical condition must be given the closest attention.
Where is the silent block used
On the front axle, silent blocks are used to mount shock absorbers, anti-roll bar and jet rods. In addition, they are used to mount the engine and gearbox. On the rear axle, they are mainly found in the torque rod mounts. The standard service life of rubber-metal joints is about one hundred thousand kilometers, but very often it is significantly reduced due to poor road quality. The driving style of a particular car owner also has a significant impact on the condition of the part. As already mentioned above, the timely replacement of silent blocks is very important and, by the way, does not require a mandatory visit to a service station.
Determining wear
The reason for examining silent blocks will be a knock in the suspension that has appeared. Having found a backlash during an external examination, a change in the appearance of the elastic insert or any mechanical damage to it, the hinges must be urgently replaced, otherwise other suspension elements will also require replacement.
Methods for determining the condition of the suspension of your car can be found on this site.
As with almost any repair, there are two options when replacing silent blocks. The simplest and most reliable, but at the same time, the most expensive option is to contact a car repair shop. A more economical way would be to independently perform this operation, but for sure this process will turn out to be more lengthy and troublesome, since there are a number of conditions for its successful implementation.
Self-replacement
Firstly, it is desirable to have a garage or other suitable premises. Secondly, you need a certain set of tools. This is a lever-type press for removing and installing a hinge, and special mandrels for this, and various types of hammers. There are, of course, craftsmen who can get by with one sledgehammer, but here one must be extremely careful not to damage the polyurethane or rubber insert. In addition, if a car enthusiast does not have enough technical skills or simply does not have the time and desire to do repairs, it would be better to contact a car service, otherwise the desire to save money on minor repairs can be too expensive. It is also imperative to turn to the help of professionals when replacing silent blocks in the mounts of power units or gearboxes, since there is no way to do without specialized equipment and proper knowledge.
In any modern vehicle, there are many parts and assemblies, each of which is an important part of the car. And if the state of large nodes, as a rule, is periodically monitored by the owner of the machine, then small elements, such as silent blocks, are often left without due attention, and their failure can lead to various negative consequences. From this article you will learn how to replace the silent blocks of the rear beam without the involvement of specialists.
Signs of wear on the silent blocks of the rear beam
New ones with a careful driving style can last a long time. Manufacturers usually produce vibration isolators with a large margin of safety, which guarantees their stable operation for a long time (up to 90-100 thousand kilometers). However, an aggressive driving style, combined with poor road surface quality, significantly reduces the service life of parts.
The wear of the silent blocks of the rear beam is often indicated by uneven abrasion of rubber and poor vehicle stability during cornering. The appearance of squeaks in the rear of the car body and blows to it while driving on poor-quality road surfaces also signal that the silent blocks of the rear beam need to be replaced immediately. It should be remembered that the appearance of the symptoms described above may be inherent in the presence of any other defects, therefore, it is imperative to carry out thorough diagnostic work on the entire rear of the body.
Buying new silent blocks
When choosing a silent block, you need to remember why this part is needed, what role it plays in the operation of the car. Since this suspension element is designed to dampen vibration, its components must also be of high quality, especially for the filling component - rubber. While metal parts wear out very rarely, rubber can fail more often. Therefore, its quality must be at the highest level, or an analogue is used - polyurethane. This material has long been used for silent blocks, but out of old habit, drivers still choose rubber.
Why is this analogue better? Consider advantages polyurethane:
Life time. This is one of the basic requirements for any element and detail. The service life of a silent block with a layer of polyurethane increases five times. High resistance to temperature loads. Polyurethane tolerates sudden changes in temperature well. Resistant to heat and frost. With such abilities, the operation of the silent block does not change at all, regardless of the weather.
solid structure which improves vehicle handling. But, by and large, both of these materials are equally in demand. The fact is that car manufacturers equip cars with both rubber and polyurethane fillers. And then the driver chooses for himself: ride comfort with rubber fillers, or improved handling, but less comfort (especially for passengers) with polyurethane.
When buying new silent blocks, it is best to get qualified advice from specialists representing a particular car shop. This is explained by the fact that vibration isolators designed for various car models practically do not differ from each other visually, however, they have a different outer diameter. Note! Before proceeding with the independent replacement of the silent blocks of the rear beam, you need to take care of buying a special puller. If for some reason you cannot purchase this tool, you can make it yourself.
How to make a silent block puller?
Before you start working on your own production of a silent block puller, you should consider the drawing and look at the finished store version. In the markets, such devices have a similar appearance to home ones, since their design is very simple - a few metal parts and bolts of the appropriate size. Hydraulic silent block puller - universal. With it, you can perform both the removal of devices and the pressing. It is not difficult to make such a mechanism - just a few parts and a couple of hours of time are enough, but you can use it every time you repair suspension parts. So, the tools that will be needed for the production of a puller are:
- a set of motorists with many keys and screwdrivers;
A small piece of strong metal pipe with a diameter that is slightly larger than a specific silent block;
Several large steel washers;
Long bolt with high quality thread;
Special clothing and construction gloves.
The workflow should be as follows:
1.
We study the entire structure of the car and, in particular, its suspension. We examine the new and old part, analyze their structure and try to understand how best to use the puller.
2. On one side of the prepared pipe, we insert a silent block, which should be replaced according to the plan, and on the other side of the pipe we insert a new mechanism. The scheme of work is to squeeze out the old one with a new part (so neither one nor the second will be damaged).
3. We direct the new silent block exactly to the seat, take the prepared bolt and twist it to the center. At first, twisting can be a little difficult, in which case it is worth tapping the parts with a hammer a little and continuing the process. Starting from the middle, this bolt will go in so easily that it can be turned with two fingers. But perform this process only with gloves, so as not to damage your hands.
4. If you want to keep the old part, then such a puller does not provide for this process, and the worn part can simply fall into the sand. Therefore, you can additionally build a small stand that will perform this function. It can be a simple cup with metal handles in the form of a wire or some other device.
There are other ways and improvised means that can serve as a removable mechanism. When creating such a device with your own hands, consider what is in your garage and which of these is the least necessary. These are the details you can use. Use your creative imagination.
It should be understood that depending on which beam of the car is being repaired, there may be a different silent block, but the instructions for creating a puller described above will be suitable for different types of devices and can be used both for the rear and for the front. When creating a device, it is worth remembering that a certain car model has its own parameters and its parts, which can be different in structure and size. It is important to take into account all the features of the car so that the created puller is suitable and can work with this device.
It is not so difficult to make a puller for silent blocks with your own hands, so try to make it from improvised materials - this way you will save a lot of money.
Step by step replacement process
1. It is necessary to replace silent blocks after the car is installed on a special lift, overpass or viewing hole. The wheels of the vehicle must be securely fixed with wheel chocks. To ensure good access to the part to be replaced, the rear wheel must be removed.
3. Using a wrench with a 19 mm opening, the nut of the fastening bolt connecting the rear beam and the bracket is unscrewed.
5. At the next stage, a wooden beam is installed between the beam and the car body, after which it is possible to dismantle the silent block that needs to be replaced using a special puller.
6.
Before installing a new silent block, the seat is thoroughly cleaned of dust, dirt and corrosion, lubricated with a solution of water and soap, after which the new silent block is pressed in with a puller. When all the steps described above are completed, you need to start assembling the car in reverse order. After the work carried out, the wheel alignment angles of the vehicle are restored.
Actually, the work itself does not seem to be difficult if there is a puller. And if it is not there, then what to do? Therefore, we write for those who repair a car with their own hands. No need to complicate the task if you do not have a special puller. Listen to the advice of car mechanics: do not fool your head and knock out - hammer silent blocks on the beams with a hammer. At the end of the article, I would like to note that a serviceable silent block helps the car drive smoothly, without unnecessary hesitation. It can quite well remove the vibrations that come from one part of the machine to another, thereby making the movement more comfortable. A caring driver always monitors the condition of the car, therefore, adjacent details are very important for him.
The suspension of the car plays a unifying role between the body and the roadway. This is an ordered set of units and mechanisms that provide the necessary smoothness of the machine during movement.
The controllability and maneuverability of the vehicle primarily depends on the serviceability and reliability of the suspension. Defective suspension components are a danger to the driver and passengers. According to statistics, every 5th accident was associated with a faulty car suspension.
One of the main elements of the vehicle suspension is the silent block. It is he who takes all the loads transmitted by the wheels of the car to the body of the vehicle. Due to it, the directional stability of the car is largely ensured.
What is a silent block?
The silent block also has another name - a rubber-metal hinge. It consists of 2 combined metal bushings separated by a strong elastic polyurethane insert.
Its primary task is to dampen vibrations in the joints of parts that occur during the movement of the machine. Irregularities in the road surface, pits and other obstacles transfer a large number of shock loads to the vehicle suspension. Up to 90% percent of them are taken over by the silent block.
The suspension of the car uses two types of rubber-metal hinges for the front and rear wheels. This allows you to evenly distribute the shock load along the entire length of the suspension. Additionally installed in the fastening elements of the gearbox and motor.
Service life of silent blocks
High-quality silent blocks, if properly installed, can be used even under the most adverse conditions for a long period of time. On average, the life of this suspension element ranges from 70 to 150 thousand kilometers.
The significant difference in the minimum and maximum period of use is due to the quality of the product. Cheap products made of low-quality material will not be able to withstand serious loads and will quickly stop working correctly.
Often, the active operation of the machine in poor road conditions plays a significant role in reducing the life of silent blocks. First of all, this is driving on a dirt road or off-road.
Signs of malfunction of silent blocks
The poor condition of roads with the active use of the machine creates an additional load on the suspension. As a result, the silent blocks that take the first hit begin to experience additional load.
The greatest load falls on the elements of the levers and suspension rods. For preventive purposes, experts recommend performing a health check of silent blocks every 50 thousand kilometers.
This will make it possible at an early stage to identify possible problems in the operation of the suspension and correctly replace the silent blocks. Often, if the car has not been subjected to a routine inspection for a long time, critical malfunctions can appear that have a serious impact on the safety of driving.
Today, the following signs of a silent block malfunction can be distinguished:
- one way;
- Lateral tire wear;
- Violation of vehicle directional stability during braking;
- Vibration of the body when the car is moving;
- External changes in the integrity of silent blocks;
- Suspension squeaks when the vehicle is moving;
- Increasing the "stiffness" of the suspension.
Each of these signs or they together indicate a possible problem in the operation of the silent block. Do not ignore them and continue to operate the machine.
Such a disregard for one's own safety can end very badly for the driver and passengers.
If a malfunction of one or a group of silent blocks is detected, you cannot hesitate. The vibration created by the machine during movement will not be damped by the rubber suspension elements and is transmitted to other parts that will begin to collapse.
Ignoring the penny operation of replacing the silent block can result in significant material costs. The greatest difficulty associated with the replacement of these elements is pressing. The operation requires the use of special equipment.
Of course, if the task is to save money at any cost, you can turn to garage craftsmen who perform the pressing of silent blocks on handicraft equipment. It must be remembered that the quality of work in this case is very low. A guarantee for the work performed is almost never given. All actions are performed at your own peril and risk.
If you need to properly replace the silent blocks, it is best to contact specialized automotive repair centers. Specialists will be able to quickly and efficiently perform all operations for the replacement of rubber-metal elements.
The cost of replacing the product consists of the price of the rubber element itself and its pressing. As a rule, the entire operation of replacing silent blocks does not take much time.
Thank you for your attention, good luck on the road. Read, comment and ask questions. Subscribe to fresh and interesting articles of the site.
A silent block is a part of a car whose task is to reduce the noise of the suspension. The silent block is an intermediary between the suspension element (subframe, spring, shock absorber, lever, etc.) and the rigid body structure. If you screw a metal suspension part to a metal body part, you will perfectly hear every vibration of the suspension, the connection will be too rigid, which will reduce the comfort level of the car.
How the silent block works
At its core, a silent block is a cylinder inside which rubber is inserted, and so that the rubber does not wear out on the mounting bolt, a metal sleeve is inserted inside the rubber. See the picture for how it looks in real life.
As a result, all blows to the suspension are swallowed by the rubber part, and almost nothing comes to the body.
How to understand that the silent block is out of order
It's simple: it ceases to perform its functions, and you begin to hear blows when driving through bumps with a large amplitude of wheel travel (rails, deep bumps). If the suspension began to knock, inspect it from the pit. In a failed silent block, the rubber part is torn, and when the lever is moved, you can see that the silent block allows its inner sleeve to move too much.
Since the silent block is no longer able to hold the suspension assembly, the clarity of the suspension is disturbed, the car may begin to wag, requiring steering. Of course, it will no longer be possible to talk about normal wheel alignment, and the master will not be able to adjust the suspension according to the new one, since when the car is displaced, the wheel alignment will constantly change. A good diagnostic method: an air stand, on which a sufficiently large load is created on the wheel, as a result of which all sore spots come out.
What silent blocks are
They are all arranged in the same way, however, to prevent the transmission of a large amount of noise, or to increase mobility, the rubber part is often not made in one piece, but, as it were, consisting of two parts connected by partitions. Sometimes, in order to reduce wear resistance, the rubber part is replaced with a polyurethane counterpart. Polyurethane silent blocks are somewhat stiffer and noisier, but in general their mileage is greater.
Causes of failure and what breaks in the silent block
It is rather difficult to imagine that the metal parts of the silent block break. If they say that the silent block has broken, then the rubber component of the part has begun to tear or has already broken. There are three reasons for the failure of silent blocks:
- Long service life, as a result of which the rubber dried out, lost elasticity and began to crack and tear
- Chemical attack on the rubber part. For example, too much oil got on the silent block, which corroded it.
- Wrong installation. The tightening of the silent block bolts should be done only when the car is on wheels, and not on weight. But alas, many car services do not comply with this rule, as a result, the wheel tightened by the canopy is at the extreme point, and when it gets on the wheels, the silent block twists strongly and the rubber will tear over time without leaving even a third of its life. Another subtle point is the installation of a silent block with partitions. Such silent blocks can be installed in a strictly defined position, and if it is placed incorrectly, the silent block will fail very quickly.
How to replace the silent block
As a rule, the silent block is first screwed to one part or pressed into it, which mates with its outer shell, after which the part is put in its place and screwed with a bolt threaded through the inner sleeve of the silent block.
Knowing how the silent block is installed, it is not difficult to guess that it is removed either by knocking out or unscrewing. When knocking out or pressing out, it is very important not to damage the mating plane of the silent block and the suspension element, since the silent block may then enter loosely or not be pressed in.
When installing, pay attention to how the silent block should stand, since not all silent blocks can be placed arbitrarily. If the silent block has a design with partitions, it must have a strict working position. If you ignore the strict installation position, the load on the partitions will be too large and the silent block will fail.
The tightening of the suspension with joints through the silent block is carried out exclusively in the position “the machine is standing with its wheels on the ground”, since the suspension must take the working position before tightening. If you ignore this rule, the silent block will twist and its resource will be significantly reduced.
