What is four-wheel alignment?
Because there is a certain relative position between the four wheels of the vehicle, the steering mechanism (the assembly connected with the steering wheel is a part of the suspension system) and the front and rear axles (the transmission shafts powered by the front and rear wheels are also a part of the suspension system), this position is the standard value set by the manufacturer. Adjusting and restoring the installation in this position is four-wheel alignment.
Why is there a relative installation position:
In order to avoid this problem becoming more and more difficult to understand, I will simply say that the wheels of the car are not installed perpendicular to the ground, and there are "camber" and "toe angle" in the wheels. The next time the car is serviced, it will be hoisted by the bench, and when the wheels are off the ground, you can still see it from the right rear.
A normal car is figure-eight, so what are the functions of camber and toe angle? In a word, it can be summarized as: eliminating the harmful torque when the vehicle is driving and forcing the vehicle to drive in a straight line. This is why there is always a righting moment on the steering wheel when the vehicle is driving, which is the role of camber and toe angle. But is the splayed foot of a car an outer splayed foot or an inner splayed foot? What is the angle? Every car has different parameters. For the service life and safety of the car, these parameters need to be adjusted regularly (that is, four-wheel alignment).
Then the question is coming! When do you need to do four-wheel alignment?
1, the vehicle deviates and cannot keep going straight.
First of all, the most common thing is that when the car is found to deviate from the course, it will turn left or right involuntarily, and it is necessary to constantly adjust the steering wheel to keep the car driving straight. This situation is not only annoying, but also dangerous. If you are not careful, you will run to another lane. However, there is one more thing to say here. Deviation is not necessarily a problem of four-wheel alignment. For example, the inconsistency between the left and right tire pressures will also cause deviation, so it is necessary to analyze the specific problems.
2. The tire has eccentric wear.
We generally recommend driving for 20,000 kilometers or 65,438+0 years to check the tire wear. If there is eccentric wear, commonly known as "gnawing tires", it means that the rear four wheels need to be positioned.
3. Damage to the chassis and suspension caused by the accident.
The damage to the chassis and suspension caused by the accident also requires four-wheel alignment. In addition to these common situations, when the car drifts, the steering is unstable or overweight, and the parts of the suspension system are abnormally worn, it may be a problem of four-wheel alignment.
Steps of four-wheel positioning: pre-positioning detection, data detection and positioning adjustment.
Inspection before positioning: First, the four tires should be the same size; In addition, subtle differences should also be taken into account, such as tire pressure, which should be adjusted according to the standard (the tire pressure standard meets the inside of the fuel tank cover); There are more subtle inspections. The tread depth of the desktop needs to be measured. The maximum deviation of tire tread pattern depth on the same axis should not exceed 2mm. If it does not meet the requirements, the relevant tires should be replaced as appropriate. Then there is the suspension system, which needs to ensure that the chassis is in a healthy state, and finally there is no-load state. This seems to be the most easily overlooked link, and it is the same everywhere. Few people pay attention, but we need to ensure that the vehicle is in an empty state, and the spare tire and vehicle tools should be placed in their respective positions.
Data detection: After the detection, the vehicle can be parked on a professional four-wheel positioning platform. After lifting to a certain height, ensure that the sensor is within the signal irradiation range of the transmitter. At the same time, after stopping the vehicle again, put the gear in neutral position, adjust the steering wheel and wheels to the standard of straight driving, and release the hand brake to move the vehicle at the next adjustment. Then fix the sensor to ensure that the sensor and receiver are unobstructed. Finally, move the vehicle in different directions according to the computer display, and further correct and check whether the suspension connection structure is slack.
Positioning adjustment: according to the data, adjust the four-wheel positioning data of each tire according to the degree of deviation. After debugging, the four-wheel alignment is not over, and the actual road test is needed to verify whether the maintenance is effective.
So the question is coming again? So where is it more cost-effective to do four-wheel positioning? First of all, the most important thing to do four-wheel alignment is that the relevant parameters such as vehicle wheels must be accurate, so when we do four-wheel alignment, we must go to those repair shops with reliable maintenance quality. For example, 4S stores are generally more expensive, and the cost of a four-wheel positioning is around 300 yuan, or even higher. Go to some brand tire service stores and calibrate the four-wheel alignment. The charge is relatively low, the one-time cost is about 100 yuan, and the general maintenance quality is no problem. It should be noted that four-wheel alignment is not unique to repair shops with four-wheel alignment instruments, and the four-wheel alignment parameters of each car are different. If the store has the corresponding parameter values, you can do four-wheel positioning for the car, otherwise it is recommended to go to the 4S shop.