Do-it-yourself wheel alignment: 2 wheel geometry adjustment units

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Author Sergey Kovalev Reading time 7 min. Views 225 Published 06/27/2017

Any service station (STO) offers to perform wheel alignment adjustments for a “modest” fee, but there is no guarantee that modern and high-tech equipment will be used to perform this work. To avoid unnecessary costs for the services of craftsmen, you can carry out this procedure yourself - fortunately, the necessary tools are easy to find.

• 2 How often should you adjust
• 3 Signs that adjustment is needed
• 4 Is adjustment necessary after replacing chassis parts?
• 5 What should be the wheel alignment angles?
• 6 We adjust the wheel alignment ourselves

  6.1 Wheel camber: checking and adjustment

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• 6.2 Wheel alignment: checking and adjustment

Advantages of the method

The technology discussed below is widely used by both beginners and experienced motorists. Among its main advantages it is worth highlighting the following:

• High accuracy. According to this criterion, this method is not inferior to the computer method. The technology makes it possible to measure almost all angular and linear indicators, which are determined using electronic equipment. Even the slope of the site on which the machine is located can be taken into account when measuring wheel alignment and camber.
• Body parameters are taken into account. With computer diagnostics, these characteristics are not determined by the equipment; at best, computer stands can calculate the clearance value. The method discussed in the article allows you to see the natural axis of symmetry of the body and determine the location of the chassis relative to it. This will help you understand why, after wheel alignment and camber adjustments, some wheels protrude from the arches more than others.
• Disc failure does not affect the results. The parameters of the wheel rims can be important when adjusting the angles on a computer. Therefore, some craftsmen working in specialized services refuse to carry out work if the car has wheels with different offsets on the front and rear axles. The method under consideration, in turn, makes it possible to measure alignment and camber, even if different disks are on the same axis.

How to measure and adjust camber angles with your own hands: video

A high-quality wheel alignment adjustment has a positive effect on the stability of the car; it no longer skids to the sides. In addition, after adjustment, fuel consumption is reduced and tire service life is increased. Any motorist can change the wheel alignment angles with his own hands - this work does not require expensive tools or special skills.

• Author: Sergey Kovalev
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Important clarifications on the procedure for measuring wheel alignment angles

The proposed method only makes it possible to determine wheel alignment angles (AWA) in order to get an idea of ​​the current wheel alignment and camber parameters. Further work on their adjustment can be carried out either with your own hands (if you have the appropriate experience and knowledge) or in a car repair shop.

It is assumed that the measurements are carried out with a working suspension and normal tire pressure. Therefore, the corresponding work related to the diagnosis and repair of the chassis is not considered.

It is also necessary to take into account that this article does not discuss what the toe-off and camber angles should be. We will only talk about the process of their measurements. The results obtained must then be compared with the factory values, which may differ for cars of different brands and models.

Before measuring the toe-in and camber angles, it is necessary to place the car on a flat, hard surface - for example, on the concrete floor of a garage. When driving onto a work site, keep the steering wheel in the zero position. In this case, the wheels will be as close as possible to the position in which they are when the car is moving on a straight road.

If the car is raised on a jack or lift after stopping, this will lead to unloading of the suspension, then the wheels will not be level enough on the floor. To eliminate such errors, you will need turntables or sliding platforms, which most car owners do not have. Therefore, it is strongly not recommended to lift the body before taking measurements. The car's suspension should be under the usual load.

Measurements should begin by determining the vanishing angles, since these are the parameters that are adjusted on most car models. This characteristic is determined for each of the four wheels, so it is sometimes called “semi-toe.” Individual toe-off is measured relative to the longitudinal axis of the vehicle. It can be built in several ways, let's look at it in more detail.

What is wheel alignment

To increase vehicle stability when driving, ease of control and reduce tire wear, the installation angles of the front steered wheels are used. These angles include: toe and camber, longitudinal and transverse inclination of the geometric axis of rotation (caster, or, outdated, castor) of the steered wheel.

To put it briefly and concisely, wheel alignment is the installation of the front wheels at a certain angle relative to the elements of the body and suspension of the car, this is done for optimal stability of the car on the road and for the most convenient and easy control of the vehicle.

Three options for constructing the longitudinal axis of a car

There are three different methods to choose from that can be used to create a “baseline” line when calculating individual wheel alignment angles:

1. The longitudinal axis can be taken as a horizontal line that passes through the axis of symmetry of the body. It can be easily constructed by marking their midpoints on the front and rear bumpers.
2. The second option is the longitudinal axis of the chassis. This line is lined up along points that are located at the centers of the distances between the wheel hubs.
3. Quite often, the trust line is used as the longitudinal axis. It is laid strictly in the direction of movement of the rear axle of the car. This vector does not always coincide with the longitudinal lines built along the body or chassis, as in previous versions. A similar phenomenon is typical for cars in which the rear axle is turned slightly to the side. At the same time, the car drives sideways, which is often observed on old Zhiguli, Gazelles, etc.

Longitudinal axis and trust line on a car.
The angle between the “trast line” and the central longitudinal axis of the machine should ideally tend to zero. But in some cases, rear suspension defects cannot always be eliminated. Therefore, when diagnosing alignment and camber, measurements are taken based specifically on the “trast line”.

Measuring individual wheel alignment

To measure the toe-in of each wheel, it is necessary to create a corridor consisting of two parallel lines. To create them, you can use strong threads, fishing elastic bands, and laser beams. The lines must run strictly horizontally; they must be aligned to the height of the wheel centers. A basic corridor can be created in three ways:

• The first is to attach the threads directly to the wheels. This is the simplest, but least accurate method. The wheels may have different offsets relative to the arches, which disrupts the parallelism of the lines.
• The second is fixing the threads on stationary supporting structures. The method is more accurate in comparison with the previous one, but it is inconvenient because during the process of adjustments and rolling the car, the chassis may shift relative to the constructed lines.
• The third is to create a corridor around the car body using rack and pinion fastenings. The slats are fixed in the front and rear of the car, strictly in the centers of the wheels.

There are many examples of such constructions on the English-language Internet. For example, type “BG rasing string lines kit” in the search.

The corridor around the car body is made of river fasteners.

In garage conditions, it is appropriate to use the most budget-friendly and simplest method. To measure alignment and camber, you will need two aluminum slats, which can be purchased at any hardware store. One of them needs to be placed on the floor near the rear or front axle of the car. Next, you need to make marks on the rack at a short distance from the wheels - about 5 cm. Then the distance between the marks is determined, the resulting value will be the width of the measuring corridor. By dividing this parameter in half, you can calculate the location of the midline. Next, you need to attach a second strip to the marked tube and transfer the resulting marks to it.

Setting marks on aluminum tubes.

Two additional marks are applied to the car’s bumper exactly in the center. They are set using a tape measure and marked with a piece of electrical tape or masking tape.

Installing a tag on a car bumper.

Aluminum tubes are fixed using ordinary office clothespins. They are attached to bumpers, mudguards or other body elements, depending on the design features of the car.

Fixing aluminum tubes on a car bumper.

Fixing aluminum tubes on a car bumper.

Next, you need to tighten rubber cords on the slats in the previously marked places, which can be purchased at any fishing store. Instead, you can use non-elastic threads, which can be secured to the tubes with rubber bands for money. This will avoid breaking the threads, ensure the necessary tension and minimize the error in determining the wheel toe angles.

Fastening rubber cords to aluminum tubes.

At the next stage, the measuring corridor is centered along the marks that were previously marked on the bumpers. Next, you need to set the steering wheel to the zero position; for greater accuracy, you can use a building level.

Setting the steering wheel to the zero position.

After the above steps, you can already detect the lateral displacement of the wheels. To do this, measure the distances from the centers of the hubs to the threads of the base corridor and determine the difference between them. This is relevant for drivers in whose cars the wheels extend out of the arches at different distances.

Measuring the distance from the centers of the hubs to the threads of the base corridor.

Now you can start measuring the individual alignment of each wheel. Measurements are carried out by determining the distances from the lines of the base corridor to the symmetrical points of the rim of the discs in front and behind the center of the wheel. The results obtained must be recorded in a notebook or, in the absence of one, written down with chalk on the asphalt in the garage.

Determination of distances from the lines of the base corridor to the symmetrical points of the rim of the disks.

Then you need to roll the car forward or backward half a revolution of the wheel without changing the position of the lines of the measuring corridor. It is important that the steering wheel remains in the same position. Next, you need to take repeated measurements of the individual wheel alignment several times. If there are no significant differences between two measurements, they can be accepted as true. If the difference is significant, you should roll the car a few tens of centimeters more and find “crooked” wheels. This way we calculate the wheel curves. To compensate for wheel runout during calculations, we find the most frequently repeated values ​​of individual toe-in alignments.

To convert millimeters to degrees and minutes, we use the table below.

Table for converting millimeters of individual wheel toe into degrees and minutes.

When all half-toe angles have been determined with sufficient accuracy, the steering angle of the rear axle can be calculated. The presence of such an angle may be indicated by differences in the parameters of the semi-convergence of the rear wheels relative to the center line.

If adjustment of the rear wheels is not planned, you can reorient the base corridor along the trust line laid through the rear axle. To do this, you need to move the fixed slats so that the semi-convergence of the rear wheels is aligned with the new position of the corridor. Then you will need to adjust the position of the front wheels according to it, fixing the car’s steering wheel strictly in the center. Thus, the car will drive slightly sideways, but the driver will not notice it.

Measuring camber angles

To determine these parameters, the base corridor is not needed; it can be removed. Camber angles can be determined in several ways: using a plumb line, bubble level, digital inclinometer or other inclinometer.

Before you start measuring camber angles, you need to make sure that the car is standing on a level surface. If the camber is measured using a digital inclinometer, then it is enough to calibrate the device by the slope of the surface on which the car is located. To do this, apply a square to the surface and check the position of the protractor with the position of its vertical edge.

Place two vertical marks on the wheel rim with a marker or chalk. We apply the cord with a plumb line to the wing, and along the marks with a ruler or caliper we measure the distance from the rim to the cord at the top mark, and then at the bottom. The difference should be within +-2mm. We roll the car a quarter turn of the wheel (90 degrees) and make two more vertical marks. Again we measure the distance from the plumb line to the wheel rim, thereby leveling out the measurement error associated with the runout of the wheel disk.

Determination of the camber angle.

For front-wheel drive vehicles, the average values ​​of camber angles are considered to be 0 ± 1 mm; for rear-wheel drive vehicles, the normal range is +1 ± 3 mm. For wheels of sizes 13 and 14 inches, 1 millimeter of camber is equal to approximately 10 minutes of arc. It is best to find out the exact wheel camber tolerance for a specific car from the recommendations of the car manufacturer.

Measuring the camber angle using a bubble level.

The camber angle can also be measured using a bubble level or a phone with an angle measuring program installed.

Measuring the longitudinal and transverse angle of inclination of the axis of rotation

Of greatest interest is the measurement of the tilt parameters of the rotary axes. Their position is determined by two key characteristics: lateral inclination and longitudinal (caster).

A short video (2 min) about what a caster is

If the wheels of a car could turn 90 degrees and stand across the body, these parameters could be easily calculated using an inclinometer. But in real conditions this is impossible to do, so you need to limit yourself to a rotation of 20 degrees in both directions relative to the zero position. The difference in the obtained angles must be multiplied by an additional factor of 1.5 - this is necessary to compensate for errors that are allowed during the measurement process.

To measure caster, the bubble level bulb must be mounted perpendicular to the plane of the wheel.

To determine caster, you first need to turn each wheel 20 degrees in front of the steering axis: right to left, and left to right. In this case, you need to set the inclinometer to zero or write down the results. Next, the wheels are turned behind the turning axis: right to the right, left to the left. If the angle measured behind the steering axis is greater than the angle measured in front of the steering axis, then the caster is positive. If it's the other way around, then the caster is negative. The protractor should show a slight difference of a few degrees. This difference should be multiplied by the same factor of 1.5. For example, if the protractor showed a value of +2 degrees, then the caster value should be taken as +3 degrees.

The transverse inclination is calculated in a similar way, but the protractor is installed in a slightly different position. For additional convenience, you can use a smartphone, on which you should install in advance an application that simulates two mutually perpendicular bubble levels. An ordinary building level, preferably with a rotating bubble, will also work for these purposes.

To measure the lateral inclination of the steering axis, the bubble level flask must be fixed parallel to the plane of the wheel.

Measuring the level of lateral inclination of the axis of rotation.

If the task is not to measure specific numerical values ​​of slopes, but only to compare them (they are not adjustable on most cars anyway), then the results do not need to be multiplied by a correction factor of 1.5. The main thing is to make sure that the angles are equal on both axes (right and left).

In the process of self-measurements, it is not necessary to strictly observe the rotation of the wheels exactly 20 degrees, especially when there are no appropriate tools to determine these angles (for example, graduated turntables). You can turn the steering wheel about 3/4 of a turn. It is necessary to ensure that when turning left and right, the steering wheel is locked in symmetrical positions. To do this, you can put some marks on the bottom of the steering wheel. When the steering wheel is in zero position, the line connecting the marks must run strictly horizontally.

Another way to get accurate results is to draw corners on the asphalt near the wheels using a protractor. If you don't have this tool, you can use a square sheet of paper with equal sides. Folding it diagonally, we get an angle of 45 degrees. Then one corner is folded in half again, resulting in an angle of about 22.5 degrees, which is close to the standard 20. Next, you need to attach the sheet to the wheel and outline its edge with chalk, thereby creating the necessary marks on the asphalt.

Marking the corners for turning the wheel

When is it necessary to do a wheel alignment?

The installation angles may be violated, for example, when the ramp hits a curb stone during parking or when driving at high speed onto any defective section of the roadway - a pothole, hole, etc. It is imperative to align the wheel alignment angles even if uneven wear is detected. tires

1. The car noticeably “pulls” to the right or left
2. The car moves straight only when the steering wheel is turned slightly
3. After making a turn, the steering wheel does not return to neutral on its own