Knocking in the front suspension on small bumps: causes and possible breakdowns. Car repair

Car enthusiasts, and especially beginners, are afraid of any extraneous sounds when working or driving a car. Often when moving, an incomprehensible knocking of the front suspension can occur on small bumps at different speeds. Inexperienced motorists immediately go to SRT to solve problems, but experts in most cases after carrying out diagnostics of the running gear find nothing. But the knock remains, and with this it is necessary to do something. Do not rush to buy new parts for the chassis. It may well be that the reason for this knock is a trifle, a trifle. Let's try to understand this issue, because the price of the front suspension is quite serious (repair costs in the amount of up to 500-1000 dollars), so it is so important to find the cause yourself.

Common causes

Sounds may appear due to a defect in the levers of the suspension system. Often the culprits are the silentblocks. As a result, the car is poorly controlled. It can also knock because of the loss of elasticity of the spring, which works in the front suspension.

How to check silent blocks?

For the diagnosis, flat mounting is required. It will determine how badly these parts are worn. With the help of the mounting lever will move in the longitudinal and transverse direction. If there is backlash or damage, then the knocking of the front suspension blocks is to blame.

Sometimes the levers can be collapsible. Then you can replace the silentblock. To do this, the lever is dismantled and then the part is pressed outwards with a special mandrel. It is advisable to lubricate the new silicone block before installation. The planting surface must also be cleaned. After installation, the knocks should stop.

Steering

Even for the experienced service engineers of numerous car-care centers to find the cause of extraneous knocking is a serious problem. Many immediately recommend to replace the shock absorber rack. Here it is, a new one, standing by the car, and an incomprehensible knocking in the front suspension on small bumps has not gone anywhere. The car owner goes to another service, but there he is offered to replace the bearing, but after that the knock does not disappear.

When carrying out the diagnosis of the front suspension, experienced car owners begin to check precisely with the steering system. Often, the steering rack can knock, and the sound is easily confused with the way the shock absorber strikes. If it is heard on a small gravel road, then this is clearly a malfunction of the steering rack. In this case, the sounds will be heard only on one side. In addition to knocking, you can feel the vibration on the steering wheel.

The main causes of vibration in the steering

Among the popular reasons that cause a small knock in the front suspension on small bumps, there is a large gap between the steering rack and gear. This is the result of wear and tear. To make an accurate diagnosis, it is recommended to pull the steering rods up and down. In this case, carefully monitor the movement of the thrust. If she does not move, then everything is fine with her. If the traction will hang, then, most likely, there is wear of the bushes.

If the rack is turning, then the exact diagnosis is a large gap in the gearing. But this problem can easily be eliminated with the help of a brace of this very rod. Also, pulling the steering rod, you can see the broken or too worn out bushings of the steering rod attachment to the steering rack.

Another possible reason for the knock is the steering hinge. To test this hypothesis with two hands it will be difficult to cope. It will take a friend's help. The assistant should rotate the steering wheel very quickly and sharply, and the car owner - to take the hinge in such a way as to keep the hinge, body and finger. If there is wear and tear, you can feel the backlash. Then repair of the suspension in the near future will not be needed, and buy and replace will have only a hinge sleeve.

Upper support pillar

This can also cause a knock in the front suspension on small bumps. At automobile forums the theme devoted to this knock is very popular. The reasons for all are different. In the course of attempts to combat this annoying sound, car owners sort out the entire suspension, but often the knock remains.

One of the possible reasons is the upper pillar support. It consists of a rubber component as a damper and a bearing. If this rubber element has lost its elasticity, then this is the reason for this foreign knocking, which all drivers are struggling with. In order to know exactly whether this is so, measure the gap between the limiter and the support. In most cars, this is easy, but in some models this node can be closed. If the measurements show that the gap is more than 10 mm, then the support must be urgently replaced. However, this gap is not always uniform. Orient in the measurement is recommended for the average figure. It is worthwhile to carefully check this support: on many cars this sound is manifested only on one side.

Reason for knocking

Why knock? Here, at first glance, metal parts can not collide. However, the hydraulic system of the shock absorbers badly extinguishes the sharp but short movements of the rod. This function is performed by rubber supports, which must have the necessary level of elasticity. If the supports are too stretched, then they inevitably lost their energy intensity. They handle the blows worse and give them to the car body with an indignant thud.

Worn bearing bearing

These sounds are manifested in the same way as with an inelastic damper, but they are sharper and much more sonorous. In order to make an accurate diagnosis in this case, you need to remove the rack. In this case, it is recommended to take into account one rather interesting feature, which is inherent in such breakages: bearing wear is always uneven. So, the maximum wear - where it is constantly located, when the car goes straight. If after a turn of a rudder the knock for a while vanishes, then it is precisely the basic bearing.

There is also another way to diagnose. It's old enough, but effective. Again you need an assistant. The second person should swing the car up and down. The driver must at this time feel for the rod of the shock absorber rod. A knock will be transmitted to this rod. If you compare these knocking in the front suspension when you turn the wheels at different angles, then you can draw some conclusions about the state of the bearing bearing.

Another possible reason - a weak tightening of the nut on the upper support, sometimes it happens.

Spherical bearing

At automobile forums, in the themes devoted to this knock, the most various reasons of a knock in a forward suspension bracket are discussed. Ball bearings are one of the popular reasons. You can say even more - this is a classic among all possible sources of extraneous knocking.

But here there is one feature. On front-wheel drive cars knocking from ball bearings - this is a big rarity. It is more typical for classic VAZ models.

So, the worn out hinge can cause sharp beats at crossing of small roughnesses of road. Diagnose this fault easily enough - pull the front wheel in a direction across. Naturally, for this purpose it is desirable to raise the machine. Beginners can confuse the play in the ball bearing with the movements of the bearing of the hub. In this case, the assistant must press the brake before pulling the wheel, this will eliminate the hub play.

Sometimes a foreign knock can be caused by a real trifle - check rubber anthers. Hinges can not live long if the protective cover is torn.

Rack

Very often a knock in the front suspension on small hummocks is attributed to this node. In reality, the source of knocking stance happens in very, very rare cases. But it's worth checking, it's a very important site.

Strongly worn, very weak stance, let it still not flow, can cause strikes. When the car moves, and the wheels get into the pit at the same time, there is not enough effort to stop this rack, and it is not able to prevent the spring from straightening. The rack shoots the wheel down. When the wheel either touches the pit or hangs in the air, it stretches to the maximum. The impact will be in the first and second cases.

Methods of rack diagnostics

There are a lot of methods. Classic - to swing the body down, and he must smoothly rise to the normal position and stop. If so, the rack is OK.

It happens, albeit seldom enough, that the stall produces extraneous sounds due to its internal problems, for example, the nut that holds the piston is unscrewed. However, there are no knocking. The car swings when it moves, and the handling drops. In this case, the rack is replaced and the suspension is repaired.

Various damages of the shock absorber are consequences of illiterate use. The oil in these systems must have a specific specific viscosity, which also depends on the air temperature. Having warmed up the engine, the driver at once breaks from a place, and in fact oil in a rack did not get warm. If the outside is cold, then the viscosity in the rack is too high. In this case, thin and very fragile parts fail.

Dense oil may also not be associated with the weather. Sometimes excessively thick liquid is poured into the shock absorbers. Do this to increase the resistance and so that the oil does not "run away." But as a result, stability and manageability deteriorate, because tough - it does not mean good.

Unpopular causes of knocking

It is absolutely superfluous to check the stabilizer bar bracket . This part consists of metal and rubber sleeves, which are deployed in different directions and connected by a thin isthmus. Most often it is he who breaks down. On uneven roads on small hummocks and bends, you can hear a knock.

For a correct diagnosis, one arm should be pulled at the end of the stabilizer. This is better if the wheels are turned to the right side.

It happens that the engine supports wear out. The engine is actively moving at an increase in speed, on unevennesses. At certain moments, he takes out to the body a generator and a crankcase. The result is a knock. This source of knocking guesses infrequently. Many change the suspension, but replacing the front suspension does not give anything in this case.

In cars can knock anything. For example, the barrels of the washer. If it is badly fixed in its place, then the rut will knock. There are still many mysterious culprits of such sounds.

Brakes as a source of knocking

Sometimes the sounds coming from the suspension, in fact, come from the brakes. It happens that the car enthusiast checked everything, replaced everything that can be replaced. The scheme of the front suspension has already been learned by heart, but the knock as it was, and remained.

To make a diagnosis, you need to move. If the knock during braking is gone, and when the pedal is released, again resumed, then the fault is the brake pads. The same problems can arise after the installation of new shoes.

If the machine knocks, do not rush to repair the running gear. Perhaps the extraneous sound is caused by a completely different reason. In this case, only complete diagnostics can help. Maybe it's enough to replace the silent blocks of the front suspension, and the sound will disappear forever.