When the car “takes” to the side while driving, this is not only unpleasant, but also dangerous. Less than this malfunction can threaten is uneven and accelerated tire wear. But in practice, there are many cases when everything ends in a serious accident with losses. Therefore, it is strongly not recommended to operate a car that pulls left or right. The cause must be identified and eliminated as soon as possible. In this article on the site Auto without a service station, 15 possible reasons why the car “floats” on the road are considered. For each of them, typical symptoms, methods of diagnosis and repair are described.
How does the car drive straight?
At first glance, this question may seem naive and unimportant. However, this is where any repair should begin. To fix something, you must first understand how it works in good condition. So, let's take a look at how the car drives.
Acceleration is in this case the most difficult mode of operation. If the car pulls to the side when accelerating, it is most difficult to look for the cause. The fact is that during acceleration, the most different forces act on the wheels. The balance of these forces determines the direction of movement of the machine.
When a car accelerates, the straightness of its movement depends on the following four factors:
- Torque - if one wheel is "pushing" harder than the other, then it will tend to "run" forward.
- Traction - if one wheel constantly slips, and the second one clings normally, then the slippery “lags behind”.
- Rolling resistance - one of the main tasks of the engine is to overcome this resistance. It depends on the area of contact patch of tires with the road and the direction of the wheels.
- The diameter of the driving wheels - the circumference depends on this, and in the case of the wheels, the path that each of them travels in one revolution.
The same factors are important in the other regimes considered. But only selectively.
This is the mode when the car accelerates and travels at the same speed. In this case, grip and rolling resistance are just as important factors as they are during acceleration. But the torque effect is not so significant. Wheel size is also important.
When coasting, torque is not transmitted to the drive wheels, so this factor is not taken into account here. Coated adhesion can also be neglected, since in this mode, other things being equal, it is the same on all wheels. Straightness is affected only by rolling resistance and wheel diameter.
This is a mode when an accelerated car slows down due to the resistance of the engine, which is not currently generating torque (torque is transmitted from the drive wheels to the crankshaft). Only two of the four factors discussed above affect straightness in this case - rolling resistance and wheel diameter.
Braking is normal
In this mode, straightness is affected by two factors - grip and rolling resistance. Or friction, if the braking is emergency. The torque and diameter of the wheels (if they are locked) do not affect the straightness in any way.
Understanding the physics and knowing the conditions for the rectilinear movement of a car (albeit in a rather simplified form) will make it easier to identify the reason why it is pulled to the side. Simplicity comes at the expense of eliminating causes or malfunctions that are obviously impossible for a particular mode. Of course, there are problems due to which the car can pull to the side at once in all or only in several modes. This will be discussed separately in the analysis of each of the 15 reasons discussed below.
Different tire pressure
Tire pressure affects two important parameters that affect the straightness of the car. These are rolling resistance and wheel diameter. A tire in which the pressure is less than that of the "partner on the axle" has a larger contact patch with the road, and more resistance to rolling. Its diameter is also smaller. This causes a less inflated wheel to “slow down” and travel less distance per revolution than a more inflated one. Plus, it clings to the road better.
Symptoms. Since lowered tires affect three factors at once, the car pulls to the side in all driving modes. Pulls it in the direction where the less inflated wheel is located. The greater the difference in pressure between tires on the same axle, the more noticeable it leads away.
Search for a reason. Despite the fact that it is impossible to exclude this cause by primary signs, it is the easiest to diagnose. A strong spread in pressure can be seen visually. However, it should be understood that even a difference invisible to the eye is also quite suitable for causing the car to deviate from the course. In this case, you can calculate it using a manometer. A difference of 0.2 atmospheres is already enough to create discomfort when driving on a straight, flat road.
Repair. Inflate tires to the same pressure. If the car has stood for some time under the scorching sun, one side to it, then the temperature of the air inside the tire will also affect the pressure. Accordingly, you can pump everything the same way, and the problem on the road will soon appear again.
Different tires on the same axle
Different tire models can have both a different diameter and a contact area with the road. Accordingly, the effect will be almost the same as in the case of pressure spread.
Symptoms. It manifests itself in all modes on a level with a spread in tire pressure. Sometimes the pull is more noticeable during intensive acceleration.
Search for a reason. If the car is not new, and it was not you who installed the tires, pay attention to this.
Repair. Install identical tires on the axle. They should not only be of the same dimension, but also with the same tread pattern. This also significantly affects the grip and stability of the car.
Uneven tire wear
Here, almost everything is the same, but on the condition that wear is a tread that has worn off. The result is different wheel diameters and contact patches. The situation is slightly different when one of the tires has physical damage. The cord burst or exfoliated, there is a “hernia”, the tire “led” and so on.
Symptoms. Appears in all driving modes. Plus, if the tire has serious damage, in addition to pulling the car to the side, vibration or beating on the steering wheel can be observed.
Search for a reason. Look closely at the tires. Very often, in order to detect damage or uneven wear, the wheels must be removed from the machine and inspected in detail with the trained eye of a specialist.
Repair. Replace a pair of tires on the same axle, whether one is worn/damaged or both. In a car, in general, everything that has a pair must be changed in pairs - shock absorbers, wheel bearings, brake pads.
When a car has a curved rim, rolling resistance increases. Also, traction with the road surface may deteriorate, especially if it is slippery. A crooked wheel is no longer a round wheel. This means that it rolls worse (“jumps”), and can manifest itself in the form of a car pulling to the side in absolutely all modes, except for emergency braking.
Symptoms. In addition to the fact that the car pulls to the side in all modes (except emergency braking), vibration of the steering wheel is added. Even on curved wheels, the car can “float” at a certain speed.
Search for a reason. Unfortunately, in this case, without a specialist and professional equipment, it is difficult to identify a malfunction. Serious deformations can be seen with your own eyes. But often the problem is so miserable that the average person simply does not notice it.
Repair. Roll the curved discs on a special machine, or replace them with new ones.
A fairly common reason, since the roads are not ideal everywhere. The car pulls to the side because the wheels fall into the rut, and there is the effect of a train on rails.
Symptoms. The car pulls to the side only periodically and on a certain section of the road.
Search for a reason. If the track is deep, then it can be seen from the driver's seat, and you can almost always skip it past the wheels. However, there are some that are not visible.
Repair. It lies on the shoulders of the corresponding state structure.
Uneven grip of wheels with road surface
This is not a malfunction of the vehicle and applies when driving on a road with snow, ice or puddles. If one of the axle wheels gets slippery (or the effect of aquaplaning appears), the conditions for rectilinear movement of the machine are violated, and it is seriously pulled to the side.
Symptoms. If the road is slippery or wet, then it is not surprising that the car pulls to the side.
Search for a reason. Look at the road, not your phone.
Repair. Slow down to a safe speed as soon as possible.
Car wheel alignment should be adjusted at least twice a year. Also, this procedure is required after any repair of the chassis and steering parts - replacement of rubber, discs, bearings, levers, ball joints, tips, rods. If the wheel alignment is incorrect, there is a misalignment of the rolling resistance of the wheels on one axle. Roughly speaking, one of the wheels rolls where you want, and the second - where it wants.
Symptoms. Systematically the car pulls only in one direction. More pronounced at medium and high speeds. Not felt only when braking with wheel lock. It may also not occur on slippery roads, as the rolling resistance force is reduced by sliding on ice or snow.
Search for a reason. A strong toe spread is visible to the naked eye if you move a few meters away from the car and look at the wheels from the front or rear. However, in order for the car to pull to the side, a deviation of a few arc minutes is sufficient. Usually, if you regularly do wheel alignment, and nothing happened to the car after the last procedure (there was no repair and you didn’t fly into a good hole), then this reason can be discarded.
Repair. Visit the service station and adjust the wheel alignment. Please note that when the steering and chassis parts are worn, as described below, it is almost useless to adjust the alignment.
Wear of steering tips
Loose steering tips lead to the fact that the wheels of one axle cannot physically roll in the same direction. If one of them is subjected to more rolling resistance or friction, it will literally turn sideways. As a result, the car pulls.
Symptoms. In addition to the fact that the car pulls to the side in all modes except emergency braking, vibration or wobble in the steering wheel can be felt due to broken tips. In winter, when the roads are slippery, the problem disappears.
Search for a reason. You can quickly check the steering tips yourself. To do this, you need to hang each of the front wheels on a jack, and shake them in the directions in which they turn when the steering wheel is turned. If there is a noticeable backlash, you can additionally see it on the tips themselves, looking under the car.
Repair. This disease is treated only by replacing the steering tips. Unfortunately, due to the condition of the roads in many places, it is almost as consumable as gasoline. After replacing parts, do not forget to adjust the alignment.
Deformation of the steering rack or rod
When these parts of the steering mechanism are deformed, the alignment of the front wheels of the car is disturbed. As a result, exactly the same thing happens as in the case of an unadjusted wheel alignment. One of the wheels experiences more resistance than the other, and the car constantly pulls to the side.
Symptoms. In some cases, strong deformations of the steering rack or rods are noticeably felt when driving at medium and high speeds. As with toe-in, the problem may disappear or lessen on slippery road surfaces.
Search for a reason. It is determined by a visual inspection of a specialist at the service station. Serious deformations can also be seen in your garage if there is an inspection hole and the opportunity to look under the car. Problems of this kind do not appear on their own. Usually, they are preceded by a collision with a deep hole or an accident (even a small one at first glance).
Repair. It comes down to the complete replacement of deformed parts with new ones. After the restoration of the steering, the alignment of the wheels must be adjusted.
Ball joint wear
Broken ball joints lead to a violation of the correct position of the front wheels of the car. Including, their alignment may be violated, due to which the car will be pulled to the side.
Symptoms. Broken ball joints manifest themselves not only by the fact that the car is moving away from the course. They are usually also heard on a bad bumpy road. Also, their wear is felt tactilely on the steering wheel in the form of bumps when hitting bumps or pits.
Search for a reason. Checking the degree of wear of the ball bearings of the car can also be performed in a garage. To do this, you need to hang the control wheels (you can take turns) on the jack, and use a long lever to raise the ball. This manipulation allows you to see the backlash, which should not be in a working node.
Repair. The problem is fixed by replacing the ball joints. Also, today there are workshops that are engaged in the restoration of worn ball joints. They do not last very long after that, but in some cases, they last longer than low-quality new parts.
Wheel bearing wear
The wheels of the car rotate on wheel bearings. When they wear out (loose), the wheels begin to wag or look in different directions. The same thing happens as in the previous cases. The car pulls to the side in all modes, except for emergency braking.
Symptoms. Worn wheel bearings can be heard and felt while riding. They can creak, squeak, make a rattle. Also, on heavily worn bearings, the car can wag when cornering.
Search for a reason. To identify tired wheel bearings, you need to hang out all the wheels one by one on a jack, and shake them back and forth, holding the upper and lower parts of the wheel with your hands. If there is play, then the bearings are loose.
Repair. It's just a replacement for new parts. Despite the fact that the replacement of wheel bearings in theory cannot affect the position of the alignment, after this procedure, this adjustment must also be performed.
Incorrect operation of the brake system
In a car with a fully functional brake system, when you press the pedal, the same braking force is created on all four wheels. In simple terms, all wheels "stick" to the pads equally strongly. And also, when the car is without ABS, and we perform emergency braking, all four wheels are blocked at the same time. If either side brakes worse, the car pulls sharply to the side and even spins with a complete loss of control.
Symptoms. The problem manifests itself with any braking from medium to high speed. Often, an accident ends, which, with a working brake system, could easily have been avoided. The problem may disappear when braking on slippery roads, since in these conditions the system needs less effort to block all the wheels.
Search for a reason. At the first sign, you should contact a specialist. It is possible to independently identify problems with the brake system, but it is quite difficult. The simplest and most accessible is to determine the presence of air in the system by a failing or wadded brake pedal, or to examine worn or destroyed brake pads.
Repair. Depending on the nature of the malfunction: bleed the brake system; clean the working brake cylinders; eliminate system depressurization; replace the brake pads; grind or replace the brake discs.
Incorrect body geometry
If the original body geometry is violated, along with other problems, the car may begin to pull to the side. At the same time, it is not necessary that there should be an accident the day before. Metal can lead both after moving through a speed bump, and after a good hole.
Symptoms. In addition to the fact that the car drives to the side in all modes, except for braking, deformations can be seen by increased or uneven gaps between body parts.
Search for a reason. Pay special attention to those places of the body where the wheels are. According to the uneven or increased gaps between the hood cover and the wings, or between the wings and the front doors, you can already safely think in this direction and look for the reason for the car to move to the side in this direction.
Professional body geometry diagnostics is performed on a special stand, where you can see the smallest deviations from the factory dimensions and proportions.
Repair. Wrong bodywork is, of course, unpleasant, but in many cases the problem is easily fixed. Repair is called a hood or straightening.
Uneven transmission of torque to the drive wheels
This problem is present by default on some front wheel drive vehicles. The reason lies in the fact that the drive shafts have different lengths and different crease angles. As a result, the torque is transmitted to the drive wheels with a slight distortion, which is sometimes very clearly felt when accelerating the car.
Symptoms. The more intense the acceleration (but with a normal grip on the road), the more the car pulls to the side. When braking the engine, the problem can also manifest itself. In other modes, the car behaves adequately.
Search for a reason. "By eye" to determine almost impossible. You need to either know about this, or learn from experts.
Repair. If there is no wear on the drives of the car, then nothing can help here. As they say - such a design feature. If the drives are worn out, but their timely replacement will, if not eliminate, then at least reduce the problem.
Uneven vehicle load
The last reason, which few people think about. However, the car's mass balance plays an important role in its steely, straight-line motion. If the car is loaded more on the right or left side (for example, the driver is light in build, and two people who are not light sit on the right front and back), then the rolling resistance and the area of the rubber contact patch with the road change.
Symptoms. It can manifest itself in all modes, including emergency braking (more loaded wheels brake more efficiently).
Search for a reason. Pay attention to how the car is loaded.
Repair. If the problem started after an unsuccessful seating of passengers or cargo, simply transfer/move passengers/cargo.
When the car pulls to the side, it can be extremely dangerous. Immediately after the appearance of the symptoms described in the article, you should find the cause and eliminate it either on your own or with the help of specialists.