The appearance of extraneous sounds in the chassis of the car is always an alarm signal, ignoring which can lead to serious financial losses or even an emergency situation on the road. When you hear it. left-wheelThis indicates a specific area of fault localization, which greatly simplifies the initial diagnosis, but requires a careful approach to identifying the source of vibration. The nature of the sound, its frequency and dependence on the speed or quality of the road surface allow an experienced mechanic or attentive driver to determine with high accuracy which node requires intervention.
The left side of the car is often subjected to increased loads due to the peculiarities of the organization of traffic, such as left turns at intersections without traffic lights or parking at the curb. In this article, we will discuss the main reasons why it occurs. metallic or a thump, and we will help you understand whether to go to the service on your own or need to call a tow truck. A sharp increase in knocking during braking in combination with the car moving to the side is a critical sign of malfunction of the brake caliper, requiring immediate stop.
Diagnostics of a hub bearing as a source of noise
The most common cause of a monotonous hum, turning into a knock, is failure. hub-bearing. This element provides free rotation of the wheel around its axis, and when it is destroyed, a characteristic backlash appears. In the initial stages, the malfunction manifests itself as a low-frequency hum, intensifying with a set of speed, but with significant wear of the separator and bearing balls, a distinct knock appears that can be transmitted to the body.
For self-checking, it is necessary to raise the car on the jack, providing reliable fixation. Take your hands on the top and bottom of the wheel and try to shake it away from yourself and towards yourself. The presence of a tangible backlash or a characteristic click during the swing indicates the need for urgent replacement of the part. Operation of a vehicle with a destroyed bearing strictly forbiddenThe wheel can jam or come off at any time.
- 🔊 The appearance of a continuous howl, changing the tone depending on the speed of movement.
- 🛑 Heating the wheel hub after the trip (you can check with your hand, using caution).
- 🔄 The appearance of vibration on the steering wheel when driving at high speeds.
It is important to consider that when replacing a bearing, it is often necessary to replace the entire hub assembly, especially on modern cars where these units are not repairable. Use of original parts or quality analogues from proven brands, such as: SKF or FAGIt guarantees a long-term resource of the site. A substandard part can fail after several thousand kilometers, creating a repeated problem.
Problems with joints of equal angular speeds (SRUS)
If the knock in the left wheel has a pronounced metallic character and manifests itself mainly during turns, then with a high degree of probability the culprit is the culprit. slug-out drive. This assembly transfers torque from the gearbox to the wheels, allowing them to turn at any angle. The destruction of the hinge begins with the entry of dirt inside through the torn anther, which leads to the washing out of the lubricant and accelerated wear of rubbing surfaces.
Diagnosis of the external hinge is quite simple: turn the steering wheel to the stop in one of the sides and try to move from the spot. If the wheels are turned to the left, a ringing crackle or clicks are heard, the left external SRUS requires replacement. The inner hinge located closer to the gearbox usually knocks when accelerating under load or when moving in a straight line at high speeds, giving vibration to the body.
Why does it crunch when you turn?
When moving in a straight line, the hinges of the SRUS work in a gentle mode. When turning the wheel, the angle of the hinge increases, and the worn elements begin to slip and hit the walls of the body, emitting a characteristic crack. If you don’t replace the part, it may just fall apart on the move.
Ignoring the crunch of the SRUS leads to the fact that the hinge can jam, which on a front-wheel drive car is equivalent to blocking the driving wheel at speed. This is fraught with loss of control and serious accident. The cost of replacing a grenade is much lower than repairing a gearbox or recovering from an accident, so you should not delay a visit to the service.
Failure of suspension and steering components
The chassis of the car consists of many levers, tractions and bushings, wear of which is inevitable during operation. Silentblocks levers, ball supports and steering tips are consumables that are the first to take on the impacts from roughness of the road. When they are destroyed, free passage appears in the compounds, which gives rise to a deaf, but rhythmic knock, especially noticeable when passing pits or “lying policemen”.
Particular attention should be paid stabilizer. These small parts often become a source of ringing knocking, which drivers mistakenly mistake for a problem in bearings or shock absorbers. You can check them by simply shaking the hand stand: if you feel backlash in the hinge joints, the part must be replaced. Also, the source of sound can be worn sleeves of the stabilizer, which begin to creak or call.
☑️ Symptoms of suspension wear
Steering can also be a source of the problem. Worn-out steering-tips or thrust creates a gap that manifests as a knock transmitted to the steering wheel. This not only reduces comfort, but also impairs handling, making the car less responsive to the driver's commands. In some cases, it may be necessary to replace the entire steering rack if its internal bushings or gears are worn.
Brake system: hidden safety threats
The brake mechanism is a system on which your life depends, and any extraneous sounds in this area require immediate attention. Knocking in the area of the left wheel can occur due to weakening of the mounting brake caliper Or wear of the guides. If the caliper has a backlash, it will beat against the disc at each push on the pedal or when passing irregularities, emitting a characteristic metal clang.
Another cause may be the destruction or critical wear of brake pads. When the friction pad is completely erased, the metal base of the pad begins to rub against the disc, causing not only a terrible grinding, but also a vibration that can be mistaken for a knock. In some cases, a stone may fall between the disc and the protective casing, which will knock loudly when the wheel is rotating.
⚠️ Attention: If the knocking in the left wheel is accompanied by a decrease in braking efficiency or the smell of burning, stop immediately. Operation of a car with a faulty braking system is prohibited.
When replacing brake discs and pads, it is always necessary to defect the remaining elements: check the condition of the caliper anthers, the integrity of the brake hoses and the level of liquid in the tank. The use of poor-quality brake components can lead to their overheating and deformation, which again will cause the appearance of knocking and beating.
Wheel discs and balancing
Sometimes the reason is trivial and lies in the wheels themselves. Wheel drives can get deformation after falling into a deep hole, which will lead to a violation of geometry and the appearance of a beat. This beat is often perceived by the driver as a knock or a strong vibration, especially at certain speeds. Dirt stuck to the inside of the disc can also create imbalances and foreign sounds.
Wheel balancing is a procedure that many people ignore, considering it to be secondary. However, the shift of the wheel's center of gravity leads to an uneven distribution of load on the suspension and bearings, which accelerates their wear. If after the tire fitting there was a knock, perhaps the balancing weight fell off or was installed incorrectly.
| Type of malfunction | Nature of sound | When it comes to | Risk |
|---|---|---|---|
| Stack bearing | A hum turning into a knock | When moving, it increases at speed. | Wheel jamming |
| The Outer SRUSS | Ringing crackle, crunch | Turning and accelerating | Drive rupture |
| Stabilizer rack | Calling, frequent knocking | On the bumps, the cops on the bed. | Loss of resilience |
| Brake caliper | Metal clang | When braking or on the bumps | Brake failure |
After replacing any suspension elements or wheels, be sure to check the descent-shatter on the stand. Even a minimal deviation of the wheel installation angles will lead to rapid wear of rubber and the appearance of new knocks.
Self-diagnosis and prevention methods
Before you go to the service, you can take a number of simple steps to localize the problem. Visual inspection of the left wheel and the under-hood space (if the knocking is forward) often helps to find obvious defects: lubrication leaks from the SRUS, torn anthers, the absence of wheel bolts or visible damage to the discs. Weaving the car behind the arch can also reveal backlashes in the shock absorber or bearing support.
Prevention of knocking is careful driving and regular maintenance. Avoid sharp starts with wheels turned upside down, do not drive into deep pits at high speed and wash the chassis regularly, especially in winter when roads are treated with reagents. Aggressive chemistry destroys the rubber suspension elements, leading to their premature cracking.
Timely replacement of worn parts avoids a chain reaction: one broken part quickly disables neighboring nodes. For example, a broken ball support can lead to the destruction of the lever and damage to the drive. Regular inspection of the chassis on the lift at least once every 10-15 thousand kilometers will allow to identify problems at an early stage.
⚠️ Attention: Do not use WD-40 or other penetrating lubricants to “cure” knocking in rubber sleeves or Silentblocks. This will only temporarily silence the sound, but it will accelerate the destruction of the rubber, and in a couple of days the knock will become even stronger.
Self-diagnosis is useful for the initial understanding of the problem, but an accurate diagnosis and quality repair are possible only in the conditions of a service center with a lift and the necessary tool.
Frequently Asked Questions (FAQ)
Can I drive if the left wheel is knocking?
You can only drive if the knock is caused by minor malfunctions, such as a unscrewed balancing weight or hitting a stone. If the knock is associated with the bearing, the SRUS or brakes, further operation is life-threatening and can lead to expensive repairs. It is better to reach the service at minimum speed or call a tow truck.
Why does the knocking get worse on the cold?
Many lubricants thicken on cold, which can change the nature of the work of rubbing pairs. However, if the knock is clearly heard in the first minutes of movement and then disappears, this may indicate gaps in the suspension elements, which choose the backlash as the metal warms up and expands, or problems with shock absorbers, whose oil also changes viscosity.
How to distinguish the thud of a shruce from the thumping of a bearing?
The SRUS usually knocks or crunches when cornering (especially when accelerating in a turn). The bearing emits a monotonous hum or howl, which depends on the speed of movement and can change the tone during the adjustment (due to a change in the load on the axle), but does not depend on the position of the steering wheel.
Do you need to change both SRUSs if only one knocks?
No, you just need to change the faulty part. However, if the mileage of the car is large and one SRUS has already failed, the second is likely also close to wear. It is recommended to diagnose the second drive, but replacing "just in case" a serviceable part is not necessary.