Most modern cars use front-wheel drive. Its main advantage lies in the fact that the transmission design is less massive and metal-intensive compared to rear-wheel drive cars, since it does not require a bridge with a gearbox and cardan transmission.
To make cars with leading front wheels allow the constant velocity joints (CV joints), which are used in the design of the drive. A feature of this type of hinge is the possibility of transmitting lossless torque when turning one component of the drive relative to another by an angle of up to 70 degrees.
Front wheel drive shaft
The drive shaft of the car with the front drive axle should perform several functions, and at the same time. It must transmit torque to the wheel hub from the gearbox, provide the ability to move the wheel relative to the body (when moving on bumps), and also allow you to change the angle of the wheel position, that is, make turns (which is accompanied by the need to change the shaft length). And all this is done thanks to the joints of equal angular velocities.
In general, the design of the front-wheel drive car drive shaft consists of three elements:
- shaft (with splines at the ends for connection with hinges),
- internal CV joint (which connects the drive to the gearbox)
- external CV joint (for connecting to the wheel hub).
There are two such drive shafts in a front-wheel drive car, each with its own drive wheel.
Types of CV joints, their design and principle of operation
1. The drive of the right front wheel, 2. The gearbox, 3. The drive of the left front wheel, 4. The outer hinge body, 5. The retaining ring of the hinge sleeve, 6. 18. The hinge sleeve, 7. 19. The hinge separator, 8. 17. Hinge ball, 9. Outer collar of the cover, 10. 15. Protective cover of the hinge, 11. Thrust ring, 12. 14. Shaft of the drive of the left wheel, 13. Inner collar of the cover, 14. Lock of the inner hinge, 15. 20. Circlip of the cage the inner hinge, 16. 21. The buffer of the shaft, 17. 22. The housing of the inner hinge, 18. 23. The retaining ring of the semiaxial gear.
There are several types of CV joints, but on cars only two are widespread:
The ball joint design includes two cages - internal, in the form of a spherical fist (fits on the shaft), and external (made at the same time with the shaft end, which is inserted into the hub or gearbox). Between them, balls are placed in special grooves, which the separator keeps from falling out of the hinge. It is the balls and grooves along which they move that are the main working elements of the constant velocity joint, since they transmit rotation and allow you to change the angle of position of one cage relative to another.
So that the inner cage does not come off the shaft, it is fixed with a snap ring located in a special groove on the shaft. The locking ring is also used neither on the shaft ends of the outer race of the inner joint.
The tripod hinge does not have an inner sleeve; instead, a three-pin fork, mounted on a shaft, is used. On each spike of this fork spherical rollers are mounted on needle bearings. Thanks to these rollers, rotation is transmitted, the shaft with the fork can change the angle relative to the cage, and also move longitudinally relative to the external cage (enter it), which makes it possible to change the length of the drive.
The connection of the plug with the shaft is splined, but at the same time it sits on the shaft quite tightly. Additionally, the fork is prevented from slipping off by a locking ring.
It is noteworthy that tripoidal CV joints are used only from the side of the gearbox, but from the side of the hub it is not used.
Ball joints can be located on both sides. That is, one can meet drive shafts on cars with two spherical, internal tripoidal and external spherical joints, but never with two tripoidal CV joints. This is due to the features of each of these types of hinges.
It is interesting that some cars (for example, Volkswagen Golf 2) use an internal ball joint of an interesting design - the outer cage with the shaft end is not made in one piece, but they are connected to each other by bolts. In the future we will touch them a little.
The main malfunction of the hinge and their symptoms
The comparative simplicity of the design and the small number of components makes this unit reliable enough and able to work out a very long time without any intervention. But this hinge also has a drawback - it is very sensitive to contamination.
The working elements of the assembly - balls, rollers, grooves along which they move, and needle bearings have a high degree of surface treatment. And sand and dust have a fairly strong abrasive effect, so getting inside, they lead to intense wear on the surfaces, which ultimately causes the destruction of the site.
To prevent the penetration of pollution, rubber anthers are used. So they are the “weak point” of the hinge of angular velocities. During the operation of the car, rubber, constantly in contact with the environment, gradually “ages”, and cracks appear in the anther through which sand enters the hinge.
In general, this is the only reason why these nodes can break. And since they cannot be repaired, they are replaced.
The sign of failure of the SHRUS is also one - a distinct crunch when cornering. Moreover, at an early stage, this crunch appears only at a complete eversion of the wheels, but as the knot wears out, it will be audible even at small turns.
Note that the appearance of a crunch indicates that the hinge has already received damage that cannot be repaired. You can take some action early on. First of all, flush the hinge, put in new grease and replace the boot. Then you can swap the sides of the installation (that is, for example, swap the left inner hinge with the right one). Another option is to add small soft plastic chips to the grease.
But since the components have already been damaged, all these measures only slightly extend the resource and ultimately it will be necessary to change the node, and it is better to do this before it completely collapses, which usually happens on the way.
From the foregoing, it can be understood that the only way to maintain the hinge is to periodically check the condition of the boot and if any slightest damage is found, immediately replace it. After all, a rubber element will cost much cheaper than a constant velocity joint.
Replacing the CV joint - the operation is relatively simple to perform, but there are a number of nuances when conducting an operation with an external and internal node. Also, the features of the work depend on the design of the hinge.
Next, we will examine how the replacement of external and internal CV joints is performed using several cars as an example, which use drive shafts of various types.
Replacing an external CV joint
Since on all cars the external CV joint is ball, the further sequence of work is almost the same for any model, with the exception of some minor nuances. We will consider the dismantling of the unit and its replacement on the VAZ-2110 model.
It is noteworthy that the CV joints are one of the few nodes in the design of a car that does not require a pair replacement. That is, if any one hinge begins to crackle, then we just replace it, we don’t need to touch the rest.
Of the tools for the work required:
- a set of keys and a set of heads with a handle and rods (a head for 30 is required),
- mallet or ordinary hammer with a wooden extension,
- steering tip puller.
Of the parts and supplies you will need:
- new hinge
- a new nut of fastening of trailer of a shaft,
- clamps (it is better to purchase not tape, but with a screw tightening),
- SHRUS-4 grease or its analogue (intended for use in constant velocity joints),
Next, we consider the sequence of disassembly, as well as indicate some tricks that will help more quickly carry out the work. So:
- The car is installed on a viewing hole, immobilized.
- So far, all the wheels are in place, we take the head by 30, we tear it off and loosen the shaft mounting nut on the hub. This nut is screwed, so it will not be easy to unscrew it, since considerable effort will be required, for which you can build up the key with a pipe segment. On a jacked-up car with the wheel removed, loosening the nut will be very difficult.
- After loosening the nut, jack the necessary wheel and remove it.
- To pull the hub off the shaft end, you need to provide the rack with free movement. To do this, unscrew the mounting of the ball joint of the suspension arm to the hub.
- Using a puller, disconnect the steering tip from the rack.
- We unscrew the nut completely.
- We take up the brake disc and pull the hub towards ourselves to pull it off the shaft end.
- After the shaft comes out, we take it aside,
- When replacing an external CV joint, it is not necessary to completely remove the drive shaft, that is, it is not necessary to pull out the inner joint.
- Next, we dismantle the external assembly itself from the shaft. To do this, weaken or cut (bite) the clamps, and then pull the boot from the SHRUS (you can just cut it, because it is no longer needed).
- We climb under the car and with the help of a hammer with a tip knock the hinge off the shaft. The strikes must be of small force, the main thing here is to knock the knot off the retaining ring, and it will come off the shaft splines themselves from the effort of the hand.
After that, the assembly is performed. First, a new boot is put on the shaft, and then a new hinge is mounted on its splines. It remains only to put it so that the circlip is in the groove made in the inner clip. To do this, we again use a hammer with a tip and light blows, we put the hinge in place.
We put in the grease (we do not regret it), pull the boot on the edge of the outer race, after which the rubber element needs to be squeezed a little by hand to remove air. It remains to fix the boot on the cage and shaft using clamps.
We assemble the assembled shaft with a new joint in the hub, bait and tighten the nut until it stops. Next, we collect everything back - install the steering tip, suspension ball joint, wheel.
After removing the car from the jack, tighten the fastening nut with a key with an extended shoulder. It remains only to tilt it to prevent spontaneous unscrewing.
Replacing inner joint
Next, we will consider how to change the internal CV joint (ball) on the same VAZ-2110. In this case, an additional mount is required from the tool.
Some of the works do not differ from those described above, therefore they will be indicated briefly. Replacement is done like this:
- We put the car, jacking, remove the wheel (you do not need to loosen the nut).
- Disconnect the ball joint and steering tip.
- We climb under the car. We take the mount and drive it between the inner joint and gearbox. Using it as a lever, push the trailer out of the box, while asking the assistant to pull the hub onto himself.
After the trailer ends out of the gearbox, we replace identically to the one described above - cut the boot, knock down the hinge. Then we put a new boot on the shaft, put a new SHRUS with a hammer and a tip, put grease in, put on the boot and fix it with clamps. Next, install the shaft end in the gearbox and push the hub into the box until it stops (you cannot put it with the hammer blows on the hinge so as not to damage the new boot).
Now a few words about replacing the internal CV joint with a Volkswagen Golf 2, in which the hinge to the limit switch is bolted. This design provides even easier disassembly, since it does not require disconnecting the suspension arms from the hub.
To remove the hinge, you just need to unscrew the 6 bolts, after which the shaft together with the hinge can be lowered down to remove (knock down) the CV joint, but you do not need to remove the trailer at all. And then we install a new boot, set the knot on the shaft, lubricate and fix the clamps. We replace the shaft with the new hinge to the limit switch and connect them with bolts.
Features of replacing a tripoid SHRUS
Finally, we will consider how the internal tripod hinge of angular velocities changes using the example of the Ford Focus 2. The tools will require the same as above, as well as the universal three-armed puller and tongs for removing the snap rings.
The complexity of the replacement is that you have to completely remove the drive shaft. Everything is done like this:
- We take out the external hinge from the hub (identical to VAZ-2110).
- We climb under the car, cut off a large clamp on the inner CV joint, and pull off the boot.
- We remove the shaft (it remains on the external hinge in assembled form on the one hand and a three-axle fork - on the other, the external cage remains in the gearbox).
- We remove the external clip (we push out the trailer with the help of a mount driven between the clip and the gearbox),
- Remove the snap ring holding the fork with forceps.
- We pull the plug from the shaft with a puller.
- We put the boot and the new element on the shaft and install the snap ring back.
- We put in place the outer clip (you can carefully hammer with a hammer with a tip).
- Install the drive shaft.
- We put grease, pull the boot on the outer cage and fix it with clamps.
- We collect everything shot in reverse order.
These instructions are suitable for almost any car, but it is necessary to take into account the design features and this applies primarily to disconnecting the lower levers from the hub.
As you can see, there is no particular difficulty in replacing CV joints, and all work can be done independently in garage conditions.
When to change the constant velocity joint
There may be several symptoms of malfunctioning of such devices. Usually, drivers by the sounds from the car's suspension determine that a constant velocity joint replacement is needed. This is evidenced by a crack in a sharp turn of the machine. To make sure that the SHRUS replacement is urgently needed, you should stop and turn the wheels to the extreme position. A crunch that appears after starting up means that it is necessary to replace a damaged front CV joint.
The appearance of the same sounds when turning the wheels in the opposite direction means that the mechanism is coming to an end on the other side of the wheel. In such a situation, the condition of the protective covers should be assessed. It is better to put the car on a lift and carefully inspect them. If fresh grease is visible near them, replace the corrugated cover. If its gap is clearly visible, and there is no lubrication, you will need to immediately replace the CV joint.
What you need to install a new SHRUS
With a lack of locksmithing skills from the car owner, it is better to immediately go to a decent car service. It at an affordable price will replace the mechanism. Experienced car mechanics do this job quickly. If you want to do it yourself, you need to prepare:
- a set of ring keys,
- a metal pipe as a lever,
- bench vise.
You will need a new CV joint with a protective cover in the kit, fixing clamps and grease. To make it easier to change the constant velocity joint, part of the gear oil is drained from the gearbox. To dismantle the drive, the front wheel is removed from its side. Then, the hub nut is unscrewed with effort, the brake disc with caliper, ball bearing and steering tip are dismantled.
To provide more torque when loosening and screwing the hub nut, it is better to stock up on the pipe that is worn on the key. The splined drive shaft of the device from the gearbox is removed using a mount, which is used as a lever. Then, the outer joint is knocked out gently with a hammer and a wooden block from the wheel hub.
Replacing the outer CV joint
- We tear off the mounting bolts from the wheel and the wheel nut, set the wheel chocks under the rear wheels. (To make it easier to break the nuts, it is better to use an extension cord for the winch).
- We jack the car and put it on the stop (in no case do not work on the jack) and hang out the wheel.
- Remove the wheel.
- Unscrew the 2 bolts that secure the ball to the knuckle.
- If not, use an extension cord for the winch and WD-40.
- We turn the steering wheel to the side and slightly pull the steering knuckle with the strut and remove the outer part of the hub along with the constant velocity joint (for convenience, you can make a few not strong blows with a hammer).
The installed hinge together with the outer boot of the constant velocity joint is fixed in the hub. It remains to add the oil drained before dismantling into the gearbox. Such a replacement of the outer CV joint is not very difficult, and can be done independently. A partially disassembled front suspension is restored after installing a new outer joint.
Replacing the internal CV joint
Replacing the internal CV joint transmitting torque to the shaft from the gearbox is easier than the outside. To decide how to remove the CV joint connected to the gearbox, just consider it on the lift from below. It can be fixed on the box in various ways. После его освобождения от креплений достаточно повернуть колеса до упора, чтобы внутренний ШРУС был снят как не удерживаемый ничем. До того, как снять внутренний ШРУС, снимается пыльник, корпус, три ролика и стопорное кольцо, закрепляющее на валу трехлучевую вилку.She is also filming.
The internal CV joint can be removed both separately and on the drive together with the external one. Using this method, it is not too difficult to replace the internal CV joint. If you have a tripoidal CV joint, then when installing it on the back, minor difficulties are possible. The three-beam fork may not be in place. The rollers located on it may not fall into their guide grooves inside the housing. It is enough to turn the drive shaft a couple of times, and they will be there where necessary.
Keep in mind the plastic plug removed from the damaged product. It is mounted on a new grease-filled inner joint. If necessary, renew the boot of the inner CV joint. It is more convenient to do this from the shaft end closest to the transmission. First of all, the inner boot of the SHRUS is removed, the locking ring, after that the device itself. Replacing the boot of the inner CV joint does not require excessive effort and does not take much time.
When to replace
The following reasons may indicate the need to replace a constant velocity joint:
- the appearance of cracks in the protective case,
- knocks during a turn,
- peculiar crackling sounds when moving,
- breakthrough of antisplash covers.
To check the technical condition of the anthers, you need to turn the steering wheel all the way and climb under the bottom. Looking below, you will see anthers. Small cracks and the lubricating fluid flowing through them will be cause for concern. After finding such a "surprise", replace the anthers. Do not put it off until tomorrow, because tomorrow SHRUS will soon wear out under the influence of falling sand and water.
Is it possible to do without replacement
It is known that CV joints usually last a long time. However, pollution can quickly disable them. Therefore, sometimes there are discussions about the feasibility of their restoration. You do not need to do this. For the machine to work reliably, a broken CV joint must be replaced with a new one. Those who know the device of the car and have the necessary locksmithing skills, people do this kind of work on their own.
It is most wise to regularly inspect the closing covers. There may be tears, cracks and other damage. Using this method, defects can be detected in a timely manner and anthers can be quickly replaced on the internal and external constant velocity joints. It also makes sense to install screw clamps when replacing the hinge and cover. They more reliably isolate from hit of dust and dirt.
There are recommendations to replace CV joints as soon as their damage is detected. It is better not to wait until the next case becomes unusable. Ideally, with a complete removal of the drive, it is advisable to simultaneously install a new cover. In order for the CV joint to be replaced with it, a large investment of time and money is not required.
In preparation for the workflow, you will need to assemble some tools. So, you can not do without:
- a hammer
- key set
- small mount
- new SHRUS.
Having prepared everything you need, you can begin to replace.
The procedure for replacing the internal CV joint
For a quality replacement, you will have to prepare a set of tools. Not without compliance with the recommendations. After all, the lack of experience can play a cruel joke with you. This is not only about wasted time, but also about damaged parts, which nowadays cost a lot. Therefore, if in doubt, consult a specialist. Otherwise, go ahead!
- Remove the wheel
- Now you need to unscrew the hub nut and the bolt securing the CV joint,
- Remove the axle shaft,
- Remove the snap ring. The good old chisel will help you cope with this,
- Remove the CV joint. To do this, use a vise. Just be sure to put a wooden block between the lips of a vice. Otherwise, you may damage the parts,
- Replace anther. This is a must. Otherwise, what's the use of the new SHRUS, if the old anthers will still let the dirt through,
- Install the CV joint purchased in advance,
- Reassemble. Be attentive to details, do not miss any of them.
If you did everything right, then the work took you no more than 40 minutes. Of course, certain difficulties are possible that beginners sometimes encounter. But all this is solvable.