Ways to balance a driveshaft professionally and with your own hands

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Balancing the driveshaft can be done either with your own hands or at a service station. In the first case, this requires the use of special tools and materials - weights and clamps. However, it is better to entrust the balancing of the “cardan” to the service station employees, since it is impossible to manually accurately calculate the weight of the balancer and its installation location. There are several “popular” balancing methods, which we will discuss below.

Signs and causes of imbalance

The main sign of an imbalance in the driveshaft of a car is the appearance of vibrations throughout the car body. Moreover, it increases with increasing speed and, depending on the degree of imbalance, can manifest itself both at a speed of 60-70 km/h and at a speed of more than 100 kilometers per hour. This is due to the fact that when the shaft rotates, its center of gravity shifts and the resulting centrifugal force “throws” the car onto the road. An additional sign, in addition to vibration, is the appearance of a characteristic hum emanating from under the bottom of the car.

Neglecting a breakup can lead to such consequences

There are several reasons for this gap. Between them:

• natural wear of the part during long-term use;
• mechanical deformations as a result of impacts or excessive loads;
• manufacturing defects;
• large gaps between individual elements of the tree (if it is not solid).

Regardless of the reasons, if the symptoms described above appear, an imbalance check should be carried out. Repairs can also be carried out in your own garage.

Results

It is quite possible to balance the cardan yourself at home. However, it is necessary to understand that it is impossible to independently select the ideal mass of the counterweight and its installation location. Therefore, self-repair is possible only in case of minor vibrations or as a temporary method of getting rid of them. Ideally, you need to go to a service station, where you will have the cardan balanced on a special machine.

The most unpleasant thing in technology is parasitic vibration. Vibration is not only unpleasant in itself, but can also destroy the most durable and complex assembly completely unnoticed. It’s not for nothing that so much attention is paid to balancing crankshafts, wheels, flywheels and clutch assemblies.

Vibration consumes a lot of useful energy. In this regard, the driveshaft is no exception.

How to balance a cardan at home

We will describe the process of balancing the driveshaft with your own hands using the well-known “old” method. It's not difficult, but it can take a long time. You will definitely need an inspection hole into which you first need to drive the car. You will also need several weights of different weights to balance the wheels. As an option, chopped welding electrodes can be used instead of weights.

A primitive weight for balancing a cardan at home

The work algorithm will be as follows:

1. The length of the driveshaft is conventionally divided into 4 equal parts in the transverse plane (there may be several parts, it all depends on the amplitude of vibrations and the desire of the car owner to spend a lot of time and effort on it).
2. The above-mentioned weight is rigidly fixed to the surface of the first part of the propeller shaft, but with the possibility of further disassembly. To do this, you can use a metal clamp, plastic tie, tape or other similar device. Instead of weights, you can use electrodes, several of which can be placed under a clamp at once. As the mass decreases, their number decreases (or vice versa, as they increase, they add up).
3. Further tests are being carried out. To do this, they drive the car on a flat road and analyze whether the vibration has decreased.
4. If nothing has changed, you need to return to the garage and overcome the load on the next piece of the driveshaft. Then repeat the test.

Installing a weight on the cardan

Steps 2, 3 and 4 from the list above should be continued until you find an area on the driveshaft where the weight reduces vibration. Next, in the same way, it is necessary to experimentally determine the mass of the weight. Ideally, with the right choice, vibration should completely disappear.

The final balancing of the “cardan” with your own hands consists in rigidly fixing the selected weight. For this it is advisable to use electric welding. If you don't have one, as a last resort you can use a popular tool called a cold welder or tighten it tightly with a metal clamp (such as a plumber's clamp).

Balancing the driveshaft at home

There is another, albeit less effective, diagnostic method. In accordance with it, it is necessary to remove the driveshaft from the car. After this, you need to find or assemble a flat surface (preferably perfectly horizontal). Two steel angles or channels (their size is not important) are placed on it at a distance slightly less than the length of the driveshaft.

After this, the cardan itself is placed on them. If it is bent or deformed, its center of gravity shifts. As a result, in this case it will flow and become such that its heaviest part is at the bottom. This will be a clear indication to the car owner in which aircraft to look for imbalance. Further actions are similar to the previous method. That is, weights are attached to the cardan shaft, and their attachment points and mass are calculated experimentally. Naturally, the loads are fixed on the side opposite to the one on which the center of gravity of the shaft is shifted.

Another effective method is to use a frequency analyzer. You can do it yourself. However, we need a program that simulates an electronic oscilloscope on a PC, which shows the level of vibration frequency that occurs when the cardan rotates. You can find this out on the Internet in the public domain.

Therefore, to measure sound vibrations, a sensitive microphone in mechanical protection (foam rubber) is required. If it is not there, you can make a device from a medium-diameter speaker and a metal rod that will transmit sound vibrations (waves) to it. To do this, a nut is welded into the center of the speaker, into which a metal rod is inserted. A wire with a plug is soldered to the speaker outputs, which is connected to the microphone input on the PC.

In addition, the measurement procedure follows the following algorithm:

1. The vehicle's drive axle is suspended, allowing the wheels to rotate freely.
2. The driver of the car "accelerates" to the speed at which vibration usually occurs (usually 60, 80 km/h), and gives a signal to the person making the measurements.
3. If you are using a sensitive microphone, bring it close enough to the marking point. If you have a speaker with a metal probe, you must first secure it in place as close to the applied marks as possible. The result is recorded.
4. The drive shaft is marked with four symbolic marks around the circumference, every 90 degrees, and numbered.
5. The control weight (weighing 10.30 grams) is attached to one of the marks using tape or a clamp. You can also use the clamp bolt directly as a weight.
6. Measurements are then made with weights at each of the four points in a numbered sequence. That is, four dimensions when the load moves. The vibration amplitude results are recorded on paper or a computer.

Unbalance position

The result of the experiments will be numerical voltage values ​​on the oscilloscope, which differ from each other in magnitude. Next, you need to build a diagram on a conventional scale corresponding to the numerical values. A circle is drawn with four directions corresponding to the position of the load. From the center along these axes, segments are plotted on a regular scale based on the data obtained. Then you should graphically divide segments 1–3 and 2–4 in half into segments perpendicular to them. The radius is drawn from the center of the circle through the intersection point of the last segments to the intersection with the circle. This will be the point of imbalance that needs to be compensated (see picture).

The required point for the position of the compensation weight will be at the diametrically opposite end. As for the weight of the weight, it is calculated by the formula:

• imbalance mass - the desired value of the imbalance mass that needs to be set;
• vibration level without a control weight - the voltage value on an oscilloscope, measured before installing the control weight on the suspension;
• the average vibration level is the arithmetic average of four voltage measurements on the oscilloscope when the test weight is installed at the four points indicated on the suspension;
• test load mass value - the mass value of the installed experimental load in grams;
• 1.1 is the correction factor.

The usually set imbalance weight is 10.30 grams. If for some reason it was not possible to accurately calculate the mass of the imbalance, it can be determined experimentally. The main thing is to know the installation location and adjust the weight value while moving.

However, as practice shows, self-balancing the cardan shaft in the manner described above only partially eliminates the problem. You can still drive the car for a long time without significant vibrations. But it will not be possible to completely eliminate it. Therefore, other parts of the drivetrain and frame will work with it. And this negatively affects their productivity and resources. Therefore, even after self-balancing, you must contact the gas station with this problem.

If you have not yet managed to disassemble the cardan

Kardan Val Service North LLC Article

Assembling a driveshaft is an operation that requires a responsible approach.

If you are just planning to disassemble the driveshaft, be sure to mark all components using a marker or core. If you are going to change the crosspiece, you need to mark how the flange is positioned relative to the welded fork in the pipe. When replacing the bearing, place marks on the kit under the support. The same applies to other nodes!

Preliminary marking is the basis in any business. This simple operation will save you from subsequent problems with reassembly.

There are cases when the driveshaft inadvertently splits in the splines during dismantling. Or, due to inexperience, the car enthusiast did not put marks in advance when replacing the crosspiece or outboard bearing.

Take a close look; on some European-made driveshafts, marks are placed at the factory in the form of convex triangles, arrows and dots; sometimes curved balancing plates and even grease nipples act as marks.

Note: there are marks on all cardan shafts with offset crosspieces relative to each other.

If you do not find marks, you have two options - contact a specialist to balance the driveshaft or try to find the correct position yourself.

Technological repair method

Cardan balancer

But if for such a case 5 thousand rubles is not a pity, this is exactly the price of balancing a tree in a workshop, then we recommend turning to specialists. Carrying out diagnostics in repair shops involves using a special stand for dynamic balancing. To do this, the driveshaft is removed from the car and installed on it. The device includes several sensors and so-called control surfaces. If the shaft is unbalanced, during rotation it will touch the mentioned elements with its surface. This is how geometry and its curvature are analyzed. All information is displayed on the monitor.

Repair work can be carried out using different methods:

• Installing balance plates directly onto the driveshaft surface. In addition, their weight and installation location are accurately calculated by a computer program. And they are attached with factory solder.
• Balancing the drive shaft on a lathe. This method is used in case of significant damage to the geometry of the element. Indeed, in this case it is often necessary to remove a certain layer of metal, which inevitably leads to a decrease in the resistance of the shaft and an increase in the load on it in normal operating conditions.

It will not be possible to make such a machine for balancing cardan shafts with your own hands, since it is very complex. However, without its use, reliable and high-quality balancing is impossible.

Results

Balancing the gimbal at home is quite possible. However, you need to understand that it is impossible to independently select the ideal counterweight mass and its installation location. Therefore, self-repair is possible only for minor vibrations or as a temporary method of eliminating them. Ideally, you need to go to a gas station, where you will balance the driveshaft on a special machine.

Regardless of what experienced garage technicians tell you, fully balancing a driveshaft is only possible with the help of special equipment. Correcting imbalances caused by improperly assembled universal joints or faulty crossbars and the elastic joint of the universal joint is another matter. Such repairs can be done with your own hands in an ordinary garage with a panoramic pit or overpass.

Temporary elimination of imbalance

The vibration that arises along the way cannot be ignored, so at the first sign you should go to a stand for balancing driveshafts. Being outside the city, it is not always possible to get to a service station with the necessary equipment. In this case, you should perform balancing yourself. The following sequence should be followed:

1. Place the car on an overpass or over a hole in the garage, as you will need access to the driveshaft.
2. Divide the cardan in half lengthwise.
3. Conditionally divide the cardan crosswise into 4 parts. If the car owner has a lot of time, the cardan can be divided into 8 or even 16 parts.
4. Take a weight with a weight of up to 30 grams. A piece of lead or a wheel balancer is suitable for these purposes.
5. Number the parts of the cardan and attach a weight to the first section.
6. Drive onto a flat section of the road and listen to the vibrations.
7. Consistently test the car, changing the position of the weight. In this case, it is necessary to find a position in which vibration is minimized.
8. By changing the weight of the weight, you need to ensure that there is no vibration in the car interior. At the same time, visual elimination of interior rattling does not mean the complete elimination of parasitic loads on the cardan. At the first opportunity, you need to balance the cardan using special equipment; you need to visit a service station.
9. Secure the weight using welding or glue.

By balancing the shaft, the car owner will protect the car from serious repairs. Traffic safety will also increase, since the vibration transmitted into the cabin significantly distracts and irritates the driver.

Terminology

• Imbalance is a mismatch between the axis of rotation of a body and its main axis of inertia. This imbalance of the rotating elements of propeller shafts or other rotors causes vibration. The latter will cause fatigue cracks in the cardan support, which will quickly develop into breakdowns. Threaded connections subject to vibration gradually become loose and untwisted. This can lead to an emergency situation due to the gimbal falling while the vehicle is moving. In addition, vibrations have a negative impact on the driver: they contribute to rapid fatigue and distract him from assessing the road situation, and also increase the risk of an accident.
• The main axis of inertia of a tree is the axis of symmetry passing through its center of mass.
• Balancing transmission shafts is the process of eliminating their imbalance, which consists of moving the main axis of inertia until it is aligned with the axis of rotation.

Types of balancing

1. Static. It is used to detect and eliminate rotor imbalance without taking into account the forces generated during rotation. To statically balance the rotor, it is necessary to shift its center of gravity so that the axis of rotation passes through it. Used for disc rotors with a length to diameter ratio of no more than 1/4. This balancing is performed on the correction plane and is not suitable for a cardan drive.
2. Instant. To perform this balancing, the unbalanced torque of the main shaft, which is an indicator of the torque imbalance of that rotor, is determined and reduced. This is done in at least two correction planes.
3. Dynamic. Includes static and instantaneous. Used for long rotors. Ideal for balancing drive shafts. Therefore, cardan balancing is performed on equipment that uses this method.

Looking at the process of balancing a bench, it is impossible to understand what method is being used. The operation of all supports looks the same - the shaft rotates, and the display shows the position and magnitude of the imbalance.

Disassembly and assembly of the cardan

In order to avoid the need to balance the driveshaft after fixing it with your own hands, it is necessary to note the position of the shafts from which it is made relative to each other. And when you lift the driveshaft, be sure to line up the marked marks. You can see how to do this in the video. If you forgot to mark the location of the driveshaft components before disassembling, another video will help eliminate the resulting vibration.

When is cardan balancing necessary?

1. When replacing the driveshaft (shortening, lengthening, etc.).
2. After elimination, significant deformation of the cardan, which is a consequence, for example, of a strong impact.

Causes of driveline vibration

• The clearance in the bearings of the cross members is greater than the permissible values. This malfunction, like the next one on the list, can be eliminated by replacing the worn cross member.
• Loss of mobility of roller bearings of cross members due to corrosion. You can detect this defect with your own hands if, before repairing, you disconnect the fastening of at least one end of the transmission from the transmission flanges and try to move the free end to the side.
• Deep cracks in the elastic joint. Repair consists of replacing this part.
• Misalignment of the crosspieces due to alteration of the transmission shaft or due to improper assembly of the group with two crosspieces at the edges and the groove connection between them. For repair: restore the alignment of the hinges.

• Loosening of the cardan flanges and gearbox shaft.
• Unscrew the nut securing the flange to the gearbox rod.
• Defective outer bearing.
• Excessive spline play.
• Deformation of the transmission tube.

Vibrations from any vehicle component easily spread throughout the body, so it is very difficult to correctly determine their source. Therefore, if you find rumbling and shaking of the floor in the cabin while driving, do not rush to blame the cardan drive, but start repairs by inspecting the engine mounts, gearbox and their fastenings.

Precise balancing of the driveshaft

How accurately is balancing of the driveshaft carried out and how is this process generally carried out? Let's figure it out.

Let's start with the fact that the speed of rotation of the drive shaft, when measured in revolutions per minute, is equal to the speed of rotation of the wheels. But, taking into account the difference in the diameters of these elements, we can say that the imbalance of the cardan is not so noticeable, and therefore does not require such high balancing accuracy. However, any, even the smallest imbalance leads to the appearance of vibrations, which, although not noticeable by the driver, gradually destroy not only this part itself, but also the entire transmission of the car.

The secret to proper assembly

Professionals know that there are only two positions in which a driveshaft can be assembled, and here's why:

• The universal joints must operate in the same symmetry to ensure equal angular velocity;
• According to the standards of manufacturers, the flange-forks must be in the same plane, this equally applies to welded forks into the pipe.

Now it’s easy to guess that compliance with these conditions is possible only in two positions. Assemble the driveshaft, observing these conditions - if the vibration does not disappear, turn the driveshaft in the splines 180 degrees.

Regarding the installation of a driveshaft on a car. The location of the receiving flanges on the bridge, box or transfer case does not matter. The main thing is a good fit of the propeller shaft flange to the receiving flanges on the car.

This process can take a lot of time and effort. To avoid this, you can contact KardanValService-Sever and have the driveshaft balanced.

When is cardan balancing carried out?

This element is balanced in the following cases:

• identification of manufacturing defects of this part during the operation of the vehicle. This happens infrequently, but no manufacturer is immune from even a small number of defects. So, for example, the BMW company has a share of officially recorded defects of 0.5%, while VAZ has this figure twice as high;
• when replacing the driveshaft due to its breakdown;
• violation of the technological gaps between the parts of the cardan during its assembly and installation on the car (first, balancing is carried out on a stand, after which the element is disassembled and balancing is carried out on the car);
• If the driveshaft is not installed according to technological requirements, its alignment may be disrupted. In this case, the cardan is removed and sent back to the balancing stand, after which it is reinstalled on the machine;
• The most common reason that the stabilizer begins to touch is mechanical damage on the road. Being under the bottom of the car, a stone can easily get into the cardan and fly away from under the wheel, as a result of which its alignment is disrupted;
• theoretically, an imbalance of this part could be the result of corrosion that has changed the geometry of any component of the cardan, or even simple contamination. However, in this case, the imbalance will not be so large as to significantly affect the quality of this mechanism.

Car operating rules

In order for the driveshaft to last longer, you must follow some rules that will help the part be subjected to less stress during operation:

1. Try to limit driving on uneven roads, as constant shaking will negatively affect the geometry of the driveshaft.
2. Drive away smoothly, avoiding unnecessary slipping and sudden starts, which significantly increase the load on the vehicle's chassis.
3. Once you get into a hole, try to get out of it smoothly, without rocking the car. Carry special mats with you to place under the wheels to minimize the risk of breaking the chassis or driveshaft.
4. Do not shift gears abruptly to reduce the load on the special elastic coupling.
5. Contact a car service in a timely manner for a complete diagnosis of the vehicle, as well as for advice on car repair and maintenance.

How to balance a cardan on a car

In parallel with balancing the cardan, the master visually inspects all its components to determine the degree of wear of each part and the possibility of their further use. The most common fault that can be detected in this case is wear (thinning) of the grooves. Continued use of such parts is fraught with very serious damage, so it is better to replace them to avoid big problems.

Numerous videos on balancing driveshafts show that during this operation, more parts are “hung” onto the driveshaft mounted on a holder. These are the so-called balancing plates, with the help of which pressure is applied to the driveshaft, simulating the operating conditions of the unit. The stand itself is in many ways reminiscent of a lathe: in the process of unwinding a part fixed on it, its imbalance (if any) is revealed, so the master needs to get rid of it by grinding off a thin layer of metal from the surface of the machine shaft with a special cutter.

Do not forget that an insufficiently aligned driveshaft will not only cause vibrations in the vehicle frame when it moves, but will also lead to accelerated wear of the entire transmission.

Advantages and disadvantages

Cardan shaft crosspiece
Despite the objective need to use a cardan transmission in a car, this mechanism has strengths and weaknesses.

Let's start with the positive qualities. Their list is quite extensive, so it’s worth focusing on the most basic ones.

• reliability and durability. In many ways, these qualities were acquired due to the ability of the cardan to withstand heavy loads. This advantage is especially important for heavy vehicles, as well as vehicles that are often forced to drive on uneven roads and rough terrain;
• maintainability. An important advantage of the HF is the fact that individual components can be changed during the repair process. There is no need to replace the entire unit, which significantly reduces the cost of vehicle repairs;
• better steering sensitivity. It is actively manifested on rear-wheel drive cars that use a driveshaft. The drive is practically independent of the cardan, and therefore the front axle is focused on steering, and the rear axle on pushing the car;
• good acceleration. The unit allows you to load the rear wheels, but at the same time unload the front ones. This helps reduce the likelihood of such a phenomenon as slipping on the car;
• rear axle skid control. If the rear axle skids, it can be dealt with much easier by using a cardan drive;
• long service life. The element is truly reliable, and its design ensures long-term operation;
• possibility of recovery. Even when the HF is severely worn out or encounters serious breakdowns, it is possible to restore it. Although in certain cases this requires special equipment.

But there are also shortcomings in cardan shafts

And sometimes it’s worth paying attention to them

If we talk about the weaknesses of HF, then it is worth highlighting the following points:

1. The main disadvantage is the fact that the shafts do not rotate synchronously as the angle between them increases. But in reality, such a minus is not particularly relevant for cars with rear-wheel drive and all-wheel drive. The disadvantage manifests itself mainly in relation to front-wheel drive vehicles. In this regard, the cardan is usually replaced with a more complex device with a similar purpose. We are talking about a structure called a CV joint or constant velocity joint.
2. Another disadvantage is the impressive weight of the structure. Large mass negatively affects the dynamics of the vehicle and increases fuel consumption.
3. To install a cardan shaft in a car, you need to provide a special tunnel. This negatively affects the comfort in the vehicle interior, since there is sometimes a rather impressive bump running down the middle of the car.
4. Driveshafts can create additional noise and vibration.

Despite the existing shortcomings, some of them are quite conditional and cannot be considered full-fledged disadvantages of the driveshaft. Plus, manufacturers are actively working to improve the design, which allows them to get rid of some shortcomings, as well as correct errors in previous versions of cardan drives.