When the time comes for a planned replacement of the cardan crosspiece or (more likely) vibration, beating, noise and crackling begin in the area of the cardan, car owners are prepared to pay a significant amount for repairing the cardan. Most often the cardan crosspiece requires replacement. This part cannot be restored, it can only be replaced. It is not expensive, but replacement work will require removing the cardan, so be prepared to spend a whole day at the service station. If you are not afraid of difficulties, then you can change the cardan cross with your own hands.
The cardan serves to connect the gearbox and the rear (in a rear-wheel drive car) or front (in all-wheel drive) axle. Its task is to transmit rotation from the engine to the bridge or bridges. The connection point for these elements is the hinge, the main part of which is the cross. It has the shape of a cross, at the ends of which there are cups with needle bearings. The bearing is separated from the housing by a sealing ring made of rubber or plastic. For each car model, the dimensions of the crosspieces differ from each other.
Possible crosspiece malfunctions:
- Cross play
- Needle bearing wear
- Wear of the cross itself
- Leakage and lack of lubrication
- O-ring failure
- Metallic ringing when moving
- Noise and crackling in the cardan area
Theoretically, the crosspiece is a very reliable part, the service life of which should be about 500,000 kilometers. But in practice, replacing the universal joint cross occurs after a mileage of 50-100 thousand kilometers. This is influenced by factors such as operating conditions, the manufacturer of the part, and the quality of the materials used in the manufacture of the part. If your car is often used in rural areas, then dirt and various bumps will shorten the life of your cross by several times. A common reason for crosspiece failure is simple inattention during routine maintenance. Often, no attention is paid to the lack of lubrication until the crosspiece makes itself known by vibration, noise or ringing.
What is a universal joint?
The crosspiece is made in the form of a hinge that transmits torque in a constantly changing position while the machine is moving. In addition to its main purpose - transmitting rotation to shafts that operate at angles to each other, it helps dampen dynamic vibrations. The device consists of:
- the cross itself;
- o-ring;
- oil seal;
- needle bearing;
- bearing caps;
- retaining ring.
Important! If it is serviceable, it has a housing through which the needle bearings are lubricated. Fixation is carried out using punching; the connection is considered non-separable and can be disassembled with difficulty or with locking rings.
Troubleshooting
Before carrying out repairs, you need to find the cause of the problem. To do this, you will need to drive the car onto a pit or a lift. We put the transmission in neutral and climb under the car. We inspect the cardan, special attention should be paid to the condition of the crosspiece seals. Next, holding the crosspiece, we rotate the cardan itself. If the crosspiece requires replacement, the play can be noticed immediately. If there is no play, but various noises and squeaks are heard during rotation, then the crosspiece may not need to be changed. You just need to replace the lubricant. There are two crosspieces in the cardan and both need to be diagnosed. The rear universal joint crosspiece fails most quickly, since it bears heavy loads. When moving, dirt and moisture also fall more onto the rear crosspiece.
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Other types of movable joints and their combinations
One of the alternative types of movable connection for transmitting torque is the angular velocity joint, or CV joint. This connection helps to avoid uneven rotation of the connected shafts when the angle between the mating parts is more than 20 degrees - from 30 to 70.
The transmission of torque in situations of large misalignment is carried out by the intermediate shaft. It consists of an elastic coupling, a flange and a constant velocity joint. The mobility of the connection of misaligned elements in this design is ensured by an elastic coupling. It is a structure of steel liners and rubber bridges connected together. Jerks of the car transmission are damped due to the elasticity of the coupling. Cardan joints are also used in the shaft design, since there is a large misalignment between the shafts that are connected by the shaft.
The intermediate shaft is used, for example, in the design of the transmission of all-wheel drive VAZ vehicles (21213, 21214, 2131) of the Niva - Lada 4x4 families. At the same time, in cars of the current VAZ 21214 model, the universal joints of the industrial shaft are replaced with CV joints - less noisy and do not require alignment adjustment.
How to change the crosspiece on the cardan
To repair the crosspiece, it is necessary to remove the cardan. Before you disassemble, you need to know some nuances:
- Fill the nuts with waterproofing agent to make the fasteners easier to unscrew.
- Use a chisel to mark the cardan flanges and rear axle flanges. If this is not done, vibration may occur on the cardan.
- To avoid damaging the threads of the nuts, it is advisable to use a curved spanner.
- If the cardan bolts rotate, you need to fix them with a screwdriver.
First, unscrew the four bolts on the propeller shaft, then remove the suspension bearing mount. After these procedures, we remove the cardan; it needs to be removed from the gearbox splined connection. Before removing the crosspiece, it is advisable to wrap the spline part with material to prevent sand from getting in there. Before removing the crosspiece, you need to prepare a tool: a hammer, pliers, a thick screwdriver and a round tube of suitable diameter. Clamping the shaft in a vice will make your work much easier. There are special pullers for removing crosspieces, but they are often not used even at service stations. However, many garage craftsmen are able to make such a device for themselves in 10-15 minutes. Next we get the retaining rings. Often, to remove them, you need to tap them with a hammer using a spacer. After this operation, the stoppers can be easily removed with pliers. Next, the cups are knocked out of the eyes. This is done with a hammer and the same spacer that was used when removing the retaining rings. Sometimes the cups fall out on their own; most often you will have to remove them with improvised objects.
How does the driveshaft cross work?
The main purpose of the crosspiece is to transmit rotation; it mates the rotating shafts at an angle to each other. Effective work is carried out at angles from 0 to 200; at larger angles it is subject to greater overloads.
An imbalance appears, resulting in strong vibration of the car.
In the production of the device, high-alloy steel is used, which is processed and hardened in a special way. Structurally, it is made in the form of a cross, at the ends of which there are four needle bearings. The use of special materials allows it to work for a long time. The resource is about one hundred thousand kilometers. If a car enthusiast drives carefully, the service life can be extended to two hundred thousand or more.
Preparing the lugs and forks and installing a new spider
The repair will be carried out poorly if the eyes and fork are not cleaned of dirt and rust. This is done with a metal brush or sandpaper. All internal surfaces also need to be cleaned and lubricated before installing a new cross. Do not forget about the grooves of the retaining rings; they need to be cleaned with an awl or a thin screwdriver. Next, the cups are removed from the new cross, and the cross itself is inserted between the eyes. When removing the cups, you need to make sure that the bearing needles do not fall apart. If there is no lubricant under the new cups, the part should be changed, or lubricated yourself. The cups are placed on the crosspiece, then they need to be pressed in with a hammer until the locking grooves open. The repair of the cross is completed by replacing the retaining rings.
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The design and principle of operation of the cardan cross
The driveshaft cross is, as the name implies, a cross-shaped joint that ensures the alignment of all rotating elements. It connects the two yokes that make up the universal joint. The ends of the forks are attached to the four ends, or tenons, of the cross. The propeller shaft pipe and one fork are rigidly attached to each other.
Cardan shaft.
The movement of the hinge is carried out using needle bearings mounted on the spikes of the cross. These bearings are installed in holes located on the forks and are secured with retaining rings to prevent them from moving. The thickness of the retaining rings depends on the size of the permissible axial clearance.
Thus, the cardan shaft crosspiece is a flexible connection between the car engine and the drive axle. Structurally, it consists of mutually perpendicular axes that rest on needle bearings installed in the driveshaft forks.
The functional purpose of the crosspiece is to provide a movable connection, dampen the dynamic deformation of the universal joint and transmit torque to the wheels.
The body of the cross is made of alloy steel and undergoes heat treatment, which ensures high surface hardness of the studs
Crosses vary in size. The size may depend on various factors: the make of the car, its dimensions, engine power and, as a consequence, the amount of torque.
The body of this important part is made of alloy steel and undergoes heat treatment, which ensures high surface hardness of the studs. To produce the outer races of bearings and the needles themselves, special bearing steel and appropriate heat treatment are used.
High transmission efficiency and durability of the hinges are ensured by the use of sealed needle bearings on the housing studs. To ensure the reliability of such sealing of the cardan cross joints, gasoline and oil-resistant rubber is used in the manufacture of bearing seals.
Installing a cardan on a car
When installing the cardan, you need to follow several rules:
- All connections must be thoroughly lubricated
- Avoid getting sand and dirt on moving joints
- Check the condition of the crosspiece seals. If they are worn out, replace them
- Achieve a complete match of the marks made when removing the marks. If they do not match, there is a high probability of vibration of the cardan and you will have to do balancing
First we insert the splined part, then tighten the four bolts on the cardan. Don't forget about attaching the outboard bearing. All bolts must be tightened well, and then checked again. If the driveshaft comes loose while driving, the car may be thrown off the road.
Sometimes repairs may not be necessary, you just need to inject. If you don’t know how to syringe the crosspiece, then you will need a large syringe and special lubricant. If you can't find lubricant, use lithol. The rear crosspiece especially needs to be sprayed, since the bulk of the dirt gets there. Many crosses have a special hole for injection. They must be thoroughly cleaned of dirt before the process. You need to syringe until the lubricant begins to pour out. Be prepared that most of the grease will be on the ground. It is better to collect a new portion of lubricant, but do not collect it from the ground.
How to check your work
You can check your work immediately after replacing the crosspiece and installing the cardan on the car. The verification process includes the same manipulations as when searching for cross play. The cardan should also be inspected for oil or grease leaks. Pay special attention to the seals. The second stage of testing is testing in motion. During a test drive, you can immediately hear vibration, noise or beating of the cardan.
The job of replacing the universal joint is complete, and you did it yourself, spending money only on spare parts. In addition, you have completely removed and installed the cardan, now if any unit of the cardan fails, it will not be difficult for you to replace it.
How to know when it’s time to change the crosspiece and where to buy it
Before answering this question, I would like to remind you that following the rules for servicing components and operating a vehicle is the main way to avoid breakdowns. At the very least, this way you can significantly extend the time between repairs and reduce costs.
The first sign of wear on the universal joint or its bearings is vibration. Moreover, most often it starts only in a specific speed range, for example, up to 70 km/h everything is fine, from 70 to 75-80 a vibration effect appears, and then disappears again. It often happens that the driver, due to the nature of his work or the way he drives, never enters the “red zone”, and the primary signs pass by his attention.
This is not a reason to drive your car to the maximum, but only a reason to pay more attention to other manifestations!
They usually become extraneous sounds - knocking, creaking, grinding of varying intensity and frequency. Of course, you can’t always hear them while driving, especially on a bad road or during rush hour, so we advise you to periodically hang up the drive axle and let the transmission work without extraneous sounds and (or) leaving a friend outside to drive past him at different speeds so that he can listen to the sounds from outside the car.
It is necessary to clarify that the listed symptoms may be evidence of problems in other nodes and connections, therefore, to make sure that the problem is in the crosspiece, you can carry out a basic check. Get close to the universal joint so that it is convenient for you to reach it with your hands. Grab the forks and try to turn them in different directions - excessive play indicates wear on the hinge. You can make it more specific by turning only the crosspiece and one of the forks, but this is even unnecessary, because you cannot change the two trunnions separately; the replacement is carried out as an assembly.
