The appearance of extraneous noise in the car is always a signal that something is wrong with the vehicle. It is especially disturbing when metallicity It occurs when driving, changing depending on the speed or nature of the road. Drivers often describe this noise as ringing, clanging, gnashing or rhythmic tapping that can drive even the calmest person at the wheel crazy.
Such symptoms cannot be ignored, as they may indicate critical wear of parts of the chassis or brake system. If you do not pay attention in time noise-noiseSimple replacement of pads can turn into expensive repair of calipers or even a hub knot. In this article, we will discuss in detail why the wheel can rattle and how to accurately determine the source of the problem.
It is important to understand that auditory analysis is only the primary stage of diagnosis. Noise. It can be tricked into creating the illusion of a problem in one place, where the real fault lies in a completely different node. Therefore, the first step should always be a thorough visual and tactile check of all the elements surrounding the wheel.
Primary Diagnosis and External Factors
Before lifting the car on a jack or driving it to the observation pit, it is necessary to exclude the most banal reasons. Often thumping It is not caused by a breakdown of mechanisms, but by an external object that got into the structure. The most common situation is the sticking of a stone between the disc and the brake shield. The stone can emit a piercing screech when braking or a thud when moving on irregularities.
It is also worth checking the condition of wheel bolts or nuts. Weakened fasteners are not only a source of noise, but also a direct threat to security. If you hear a characteristic clang after visiting a tire fitting or replacing rubber, check the puff immediately. Wheel bolts must be tightened with the force specified by the manufacturer, otherwise the disc will "walk" relative to the hub.
⚠️ Warning: If you feel the steering wheel beating at high speed combined with metal clang, stop immediately. Continuing to drive with a weakened wheel can lead to unscrewing of the nuts and complete loss of the wheel on the go.
Another factor is the state of the disk itself. After being hit in a deep hole die-plate It can be deformed, and its inner shelf can crack. The detached piece of metal will hang inside and make sounds at each turn of the wheel. Cast discs are more resistant to deformation, but with a strong impact can crack, which will also lead to depressurization and the appearance of knocks.
Brake system diagnostics
If no external defects are found, the next suspect is the brake system. This is where most often comes up. metal-snack, which scares drivers. The main reason is the critical wear of brake pads. When the friction layer is completely erased, the metal base of the pad begins to rub against the brake disc, emitting an unpleasant sound.
In addition to wear, noise can cause jamming of the caliper. The guide calipers can rust and stop moving, which is why the pad is constantly pressed against the disc. This leads not only to sound, but also to overheating of the disk, its "blue" and deformation. In this case, the car can lead to the side, and fuel consumption will increase markedly.
To check the state of the brakes, the following algorithm of actions can be used:
- 🔍 Visually inspect the brake disc through the holes in the disc: the surface should be smooth, without deep furrows.
- 🔍 Check the thickness of the friction lining: it should not be less than 2-3 mm.
- 🔍 Pay attention to the color of the disc: the blue tint indicates overheating due to jamming.
- 🔍 Shake the caliper: it should not have backlashes, but guides should move from the effort of the hand (when the pads are removed).
Special attention deserves counter-script. Sometimes it bends or breaks and starts to touch the rotating disk. This causes a sharp, ringing metallic sound that is often confused with the stone in the brakes. Repair in this case is simple - to straighten or replace the plate, but requires disassembly of the node.
☑️ Brake diagnostics
Failures of the hub bearing
One of the most insidious causes of noise is malfunction. hub bearing. In the early stages of a break, it can hum or howl, amplifying the sound with increasing speed. However, with severe wear or destruction of the bearing separator, a distinct metal crunch or roar appears, which is transmitted to the body.
The peculiarity of bearing noise is that it can change the tone when turning the steering wheel. When turning, the load on the bearings is redistributed: on one wheel it increases, on the other - falls. If the sound is amplified when you turn left, then the problem is most likely in the right bearing, and vice versa. This is due to the fact that the destroyed bearing begins to "rattle" under load.
| Symptoms. | Probable cause | Danger. |
|---|---|---|
| Monotonous hum | Initial wear and tear | Low. |
| Crunch when turning | Destruction of the separator | Medium |
| Rumbling and vibration | Complete bearing destruction | Critical |
| Hub heating | Lack of lubrication/jamming | Tall. |
The critical point is the appearance of backlash in the wheel. If you feel a beating when rocking the wheel with your hands (when the car is raised), it is strictly forbidden to operate the car. The failure of the bearing can lead to the wheel jamming at speed or the separation of the hub along with the wheel from the car.
How to check the bearing without a lift?
Drive the car to a flat platform, put on the transfer and handheld. Swing the wheel with your hands at the top and bottom. If there is a backlash, the bearing needs to be replaced. You can also drive a short distance and touch the center of the disk (caution, it can be hot). If the hub is noticeably hot disc or adjacent wheels - the bearing is defective.
Problems with suspension elements
The chassis of the car consists of many levers, rods and bushings, which are connected by metal fingers and Silentblocks. When the rubber metal hinges wear out, backlash appears in the joints. The metal begins to hit the metal when the irregularities pass, creating a characteristic knock.
Often the source of sound is the stabilizer rack. These are small thrusts that connect the transverse stability stabilizer with levers or shock absorbers. Because of their short length and constant operation in an aggressive environment, they are the first to fail. Knocking sticks It is usually heard on small irregularities (comb) and on turns.
It is also worth paying attention to:
- 🔧 Ball supports: when they wear, a thud appears and a backlash may occur in the wheel.
- 🔧 Steering tips: makes a sound similar to the ball, but manifests itself more strongly when working with the steering wheel.
- 🔧 Silentblocks of leverage: when the rubber is destroyed, the metal sleeve begins to beat against the body or subframe.
Diagnosis of the suspension requires a thorough examination of all connections for backlashes. Use a mounting blade to sway the elements in different planes. If you hear a click or see the parts shifting relative to each other, the node needs to be replaced. Remember that the serviceable suspension works silently.
When replacing the stabilizer racks, always change them with a pair, even if only one knocks. The resources are the same, and the second one will soon start to rattle.
Defects of the wheel and tire
The source of the problem is not always in the deep parts of the car. Sometimes the culprit of the metal sound becomes the wheel itself in the assembly. For example, balancing loads. If they are poorly glued or nailed, they can fall off, dangle inside the disk or, worse, fly off on the go, disrupting the balance.
Another reason is the stratification of the tire cord or the appearance of a "hernia". Although this more often causes a hum, with strong stratification, the metal cord can protrude outward and rub against the suspension details or brake shield, emitting a grin. Visual inspection of the sidewalls and tread is mandatory.
In winter, a frequent cause is the adhesion of snow and ice on the inner side of the disk. The frozen mass can shift to the edge of the disc and, when rotating, touch the brake shield. This causes a sharp, intermittent metal crack that disappears after the ice melts or is knocked down.
⚠️ Warning: Do not try to knock the ice off the inside of the disc with wheel impacts on the go – this can damage brake tubes or ABS sensors. It is better to wait for thawing in a warm garage.
Also check for decorative caps. Cheap plastic caps often crack and pieces of rebar or fastener can hang inside, creating the illusion of a serious breakdown. Remove the caps and make a trial trip - if the sound is gone, the problem is found.
Remediation and prevention
Eliminating metallic sound begins with accurate diagnosis. If you are not sure of your abilities, it is better to contact the service station, where the masters on the lift will quickly identify the source. Self-repair is possible with a garage, jack and a set of tools, but requires caution.
Prevention of such problems includes regular inspection of the chassis. Washing wheel arches and pressure suspension elements helps to wash away dirt and salt, which accelerate corrosion and wear of rubbing vapors. Lubrication of the guide calipers and (regular inspection) tightening of the bolts will prolong the life of the nodes.
The main steps to eliminate:
- Lift the car and remove the wheel.
- Clean the brake mechanism of dust and dirt.
- Check the free flow of all moving parts.
- Replace worn parts (pads, discs, bearings).
- Build the knot using the right puff moments.
Timely replacement of worn pads prevents damage to brake discs, which saves up to 70% of the cost of repairing the brake system.
Remember that metallic This is not just discomfort, but a signal of the destruction of mechanisms. Ignoring the problem leads to a chain reaction: one broken part breaks another. Take care of your car and react to changes in its behavior instantly.
Can metallic sound be linked to the engine?
Yes, sometimes the sound can be transmitted through the body or exhaust system. For example, if the heat shield of the silencer is removed, it may rattle, and it will seem that the sound comes from the wheels. Also, problems with the SRUS (garnet) are often confused with knocking in the suspension.
Is it dangerous to drive if the wheel is rattling a little?
You can only drive to the nearest service and at a minimum speed. If the reason is the bearing or brakes, further operation can lead to jamming of the wheel or brake failure, which is fraught with an accident.
Why does sound only appear in the cold?
On cold gaps in the mechanisms more, and the lubrication thicker. Metal knocking on cold often indicates wear of the piston group of the engine (if the sound is in front) or frozen lubrication in the hub bearings. However, the sound is often based on the load, not the temperature.