Probably, for any car enthusiast, knocking in the suspension when driving on bumps will be an unexpected phenomenon, but not everyone understands why this can happen and what needs to be done to return the car to normal. Most often, owners of new cars pay their attention to such malfunctions, who for a long time enjoyed the comfort and coziness of a passenger car. One way or another, knocks in the suspension when driving on bumps always become a complete surprise for a motorist, and you need to correctly understand how to get rid of them. The main thing is to make competent decisions in a timely manner, so that later you do not have to cope with an even more serious problem.
Can I handle this?
Knocks in the suspension when riding on bumps are a very unpleasant phenomenon, but it can be completely eliminated, and in most cases, repairs are carried out without any effort on their own. There are many reasons why such a malfunction may occur, and subsequently it may begin to manifest itself even when driving on a good road. Therefore, it is highly desirable to deal with this breakdown as soon as possible and take measures aimed at eliminating it.
First of all, it is worth noting that there are a variety of types of suspensions, and each of them is distinguished by its design features, therefore, there are many reasons why knocks in the suspension arise when driving on bumps. In many respects, the characteristics of one type or another directly depend on the used wheel drive, the place in the model segment, as well as the total cost of the car itself. Some were used earlier, while others are actively used to this day and will certainly be popular in the near future.
MacPherson
For the first time, it began to be used about 50 years ago, but to this day it is in quite wide demand among modern manufacturers. Quite often, it is called a swinging candle, because the shock absorber constantly sways when the wheel moves down or up. As a disadvantage of this system, it is customary to imply a rather large camber angle, but it is used because of its fairly wide distribution, as well as its relatively affordable cost.
The main types
The two-lever system is considered by specialists to be the most advanced of all used today, and this is not at all surprising, since it provides excellent lateral stability and wheel control, as well as optimal tire wear. This design provides for the perception of any irregularities in the coating of each individual wheel, independently of the others, therefore, a knock in the suspension when driving on irregularities occurs extremely rarely.
A system with a large number of levers is also used, which is slightly similar to the previous design. Its structure provides for the use of several levers, ball bearings and silent blocks at once, and due to this design a smooth ride is provided, as well as minimal noise from the movement of the wheels. It has a small mass of unsprung parts, the possibility of lateral and longitudinal adjustments, as well as complete independence of all wheels.
The adaptive view system uses a hydropneumatic suspension as a basis , which quite distinguishes it from other types. Initially, it was distinguished by a rather complex design and heavy weight, which sometimes caused a knock in the suspension when driving on bumps, but due to its modernization, many shortcomings were eliminated, although it still has a rather complicated structure.
Causes of the problem at McPherson
In the McPherson struts, the upper part breaks down quite often, in which the shock absorber is attached to the body. Suspension springs sag quite strongly during long-term operation, and this is almost immediately reflected in the distance between the wing and the tire. For this reason, quite often “breakdowns” of shock absorbers occur during the movement of the car along some irregularities, and installing thicker gaskets between the body and the car will not solve the problem, it is better to use a normal autobuffer, and ideally, completely replace the spring with a new one.
De Dion
The scheme got its name in honor of the French engineer, and in most cases it is used in the rear axles of cars. It is worth noting that the knock in the suspension when driving on bumps on the VAZ-2121 and other cars is often found precisely because they use such a system.
The main structural difference of such a suspension is that the main gear case is separated from the rear axle, while the torque is transmitted by means of half shafts with hinges of equal angular speeds. If we talk about the main disadvantages of this technology, it is worth noting the “pecking” in the process of starting from a place, as well as the “squatting” of the car during braking.
What is it like?
First of all, it is worth considering the dependent system, which is most actively used in the Zhiguli, still rolling along the roads of Russia and other CIS countries, and which more often than many other cars have a knock in the suspension when driving on bumps. VAZ-2114 and other cars in which similar systems are used often faced various problems, but at the same time they could often be repaired even on their own. Cylindrical coil springs are used as an elastic element of this design, while four levers are used to fix the rear axle in the longitudinal direction and one in the transverse. It is due to this that good technical characteristics of this suspension are achieved, although there are some difficulties in its operation.
Semi-independent constructions, which are used by most manufacturers and are less likely to knock in the suspension when driving on bumps, are also widespread. Ford Focus-2 and other cars are equipped with such systems due to their low weight, as well as excellent kinematics of the wheels. But there is a certain drawback in it - the impossibility of using this scheme on machines with rear-wheel drive.
Common Causes of a Problem
Any extraneous noise in the area of ​​the suspension in any case indicates that a certain malfunction has appeared, and it is especially important to pay attention to this if there is a knock in the suspension when driving on bumps. Ford Focus-2 and other cars are quite vulnerable to such malfunctions, and if you do not fix them in time, in the future you can encounter quite serious complications of the breakdown. It should be understood that there are a fairly large number of different sources of such a problem, and they can come from any rubbing pairs due to wear of silent blocks and rubber bushings.
In lever systems, quite often it is the silent blocks that produce a knock in the suspension when driving on bumps. "Lada Kalina-2" and other cars show this problem more often due to the development of their resource ball bearings. Do not forget that due to the appearance of shock loads in the support, it often collapses when driving, so even today you can meet the Zhiguli and other old cars on the side of the road, which simply had a wheel torn off during movement.
For any modern suspension, the sound of worn steering rods is characteristic, and it can be determined by swaying the steering wheel. It is also worth noting that a shock absorber malfunction, in principle, in itself significantly reduces the comfort of driving, and not only is the reason why there is a knock in the suspension when driving on bumps. Renault Logan and other cars often experience similar problems, and it sometimes happens that it is not the device itself that breaks, but the installed rubber bushings that just need to be replaced as soon as possible.
You can try to restore the shock absorbers of the old release on your own, but the effect of such work will be relatively short-lived. It is customary to produce modern models with a non-separable design, so in the overwhelming majority of cases they just have to be changed if they caused a knock in the suspension when driving on bumps. Renault Logan (the causes of the malfunction are indicated above) is one of those cars in which shock absorbers often have to be completely changed, but timely repair of a car often prevents such serious malfunctions.
Among other things, it does not interfere with inspecting the chippers on the upper arms and shock absorbers.
Also quite often there are such cases when a knock in the suspension while driving on bumps on the VAZ-2110 and other cars causes wear of the rubber bushings of the anti - roll bar. In this case, the problem can be eliminated quite simply, since it is quite simple to replace worn components. Often, the problem comes from the braking mechanisms, and especially often it manifests itself in machines with disc brakes.
The rear axles have similar problems, and they often also have a knock in the suspension when driving on bumps. VAZ-2110 and other cars are faced with this part due to wear of shock absorbers and rubber bushings, but occasionally the sources of extraneous noise are wheel bearings, which also have a certain service life. Knocking in the suspension itself is not the most serious and difficult problem, but in any case you need to pay attention to it and take timely measures.
Diagnostics of the upper strut supports
As mentioned above, the upper strut supports are a fairly common reason why there is a knock in the suspension when driving on bumps. “Lada Kalina” and other domestic cars are equipped with mounts through a rubber damper and a thrust bearing, and when the first one loses elasticity, during movement along roughnesses you can pay attention to a characteristic knock in the area of ​​the front pillar.
The problem can be determined by measuring the distance between the limiter and the support, since it should be less than 10 mm. It is worth noting that some car models are equipped with a closed unit, so it will be impossible to carry out such measurements. In such situations, in order not to just analyze the entire structure, you can use the diagnostic method, which is used to check the thrust bearings and allows you to determine the knock in a particular rack. To do this, just put your hand on the "glass" in the place of mounting the rack, and then swing the front of the car from the right side. Of course, it is best to carry out such procedures with an assistant.
Having felt characteristic blows in the area of ​​the upper support, you can be absolutely sure that the main cause of this malfunction is a rubber damper or a thrust bearing. It is also necessary to pay attention to how much the fastening nut of the upper support is tightened, since quite often it is the main reason for knocking in the released state.
Checking CV joints
Immediately it is worth saying that it is rather difficult to determine the malfunction of the CV joint, and this can only be done while your car is moving. The main symptom of a hinge problem is the appearance of a sharp crack during a car turn or when trying to abrupt start from a place by turning the steering wheel.
Visually, it is not possible to determine the breakdown without preliminary installation. If you still find that the boot of the hinge has been damaged and there is no grease inside, it is imperative to carry out repairs as soon as possible.
Ball bearings
Broken ball joints quite often are the reason that there is a knock in the suspension when driving on bumps on the VAZ-2114. Such cars are often found with this problem, since in domestic classic cars such a malfunction appears especially often.
Checking the ball joint is quite simple:
- First, the car rises with a jack, after which the wheel is hung from the right side.
- Now, when the wheel is in a free state, you need to pull it several times in the transverse direction, while simultaneously observing how the ball joint behaves.
- To exclude any problems in the hub bearing, it is best to have an assistant with you who will apply the brake and block the possibility of wheel rotation.
- If in the process of checking the ball bearing starts to make some extraneous sounds or there appears a “backlash”, this will indicate the need for urgent repair or replacement.
Among other things, again, look at the boot of the support, as it must also be free from any smudges or mechanical damage.
Wheel bearings
After a full check of the ball is carried out, also engage in a complete diagnosis of the hub bearings in the front wheels. To do this, you first need to raise the car with a jack, after which the corresponding wheel is shaken down and up. If the actual cause of knocking is bearing wear, you can immediately feel it.