One of the most important elements of the front suspension is the ball joint. True, they used to be used on the rear axle, but these were isolated cases when the rear wheels were able to steer in time with the front ones (nowadays this design is practically not used). The support, as a support bearing itself, allows your wheels to deflect (simply turn), without this design this would not be possible. In this article I will talk about the device, how it works and whether it can be repaired to make it last forever. In general, as usual, there will be a lot of useful information, so continue reading...
Why do you need a ball joint?
A ball joint is, structurally, nothing more than a hinge with which the wheel hub is attached to the suspension arm. Its main task is to give the wheels freedom of movement in the horizontal plane and exclude it in the vertical. In general, ball joints are used not only in hub supports - they can be found in camber arms, in the steering linkage, and even in fastening the hood gas stops.
But until a certain time, instead of movable ball joints on swivel wheels, a kingpin joint was used - heavy, requiring periodic lubrication, and most importantly, providing the wheel with only freedom of rotation along one axis, which negatively affected handling.
The designers understood that the ball joint would take every hit from the road, so the wear and tear would become colossal. There was no point in making a part with particularly durable diamond coating, so it was deliberately turned into almost a consumable. So that if something happens, you can easily unscrew a couple of bolts and a nut and replace it with a new one.
Mounting methods
The main differences between modern spherical joints are not so much in the design as in the methods of fastening. This is due to labor-intensive costs during maintenance and replacement. The most optimal option, acceptable for the car owner, is considered to be fixing the hinge body to the suspension arm using a threaded or rivet connection. The method allows, if necessary, to quickly dismantle a worn-out unit.
Later, manufacturers began to abandon this method in favor of integrating the lever into the suspension. This design had a disadvantage, since it was necessary to change the lever assembly, even if it was not worn out. The advantage was the lightweight design. Although there is an opinion that marketers lobbied for such a system in order to increase profits from the sale of spare parts, because it is necessary to change the lever assembly. Some automakers have compromised and abandoned the rigid fixation to the lever. An alternative was a retaining ring. The support was only pressed into the lever. Examples are the Jeep Patriot or Opel Zafira C. In this case, replacement will require a press or other type of force.
Device
Technical progress has led to changes in the original design of ball joints, although they were not fundamental. The stamped halves of the body, connected by spot welding, were replaced by cast and dismountable supports - with a threaded cover, maintenance-free and serviceable - with grease fittings. These improvements were justified and useful. Today, the most common maintenance-free ball joint design consists of: a body with a spherical recess and a pin with a ball on one end and threads on the other. The boot, placed on the finger, prevents moisture and dirt from entering the housing filled with a special thick lubricant.
The main function of the ball joint is to ensure its fixed position in the horizontal plane during vertical movement of the wheel. The ball pin can rotate in the body, swinging at small angles. That is, in the plane of its attachment, the ball joint provides simultaneous rotational and linear (limited) movements of the finger.
All parts of the ball joint are usually made of steel. To reduce friction of contacting working surfaces, the spherical recess of the housing is covered with plastic or other polymer material. However, there are ball joints that do not include a polymer coating between the body and the pin. This applies, first of all, to outdated domestic cars. These models were equipped with collapsible ball joints, in which backlash was eliminated by tightening the cover.
There are two ways to attach the ball joint. In the first case, it is bolted to the lever. In the second, it is pressed into it. If a bolted ball joint fails, it can be replaced with a separate unit. To do this, you just need to buy and install it by bolting it to the lever. In the second case, you will have to change the suspension arm with a pre-installed, pressed-in ball joint. The cost of such repairs is much higher, since it also includes the cost of the lever.
Press-fitted ball joints are typically installed on Japanese-made vehicles. Asian manufacturers of auto parts offer consumers ball joints for such cars in the form of separate units. This is much cheaper, but you should be aware that their quality is significantly inferior to the original, and the lever will have to be remade in a “makeshift way”, turning it into a part that is not subject to warranty repair
Anther
A mandatory attribute of the main suspension joint is the boot. It is used on both removable and non-removable structures. The part is a replaceable one. Experts recommend monitoring its condition at least every 10-15 thousand km. mileage Timely replacement of a worn boot will help save on repair/replacement of the entire ball joint. Its task is to block the penetration of moisture, dust and dirt to friction surfaces, which contribute to rapid wear of metal parts.
Diagnostics and replacement
If, when directly turning the steering wheel of a vehicle, the motorist needs to make special efforts or a characteristic creaking occurs, then most likely there are problems with the ball joint. In addition, this will also be indicated by the occurrence of a knocking sound when the car is moving at low speeds on uneven surfaces. Another sign of failure of ball bearings is wobbling and instability of the front wheels when moving directly in a straight line. Another sign of this problem is uneven wear on the vehicle's tires.
It is quite clear that a quick and high-quality replacement of the entire ball joint device will be possible only with the help and operation of professionals. However, many car enthusiasts prefer their own labor and work. In the modern world, the question of the production of ball joints finds its answer in the thesis that this is a high-tech process that allows us to achieve a high degree of reliability and durability. However, replacing this device is one of the most common types of car repairs. The situation, of course, can in no way change until the quality of our domestic roads changes.
Useful tips
The service life of a support often depends on a lot of factors and on average ranges from 15 to 120 thousand kilometers. The life of a ball joint can be shortened by even a minimal crack in the boot. Water, sand and dirt can penetrate through it into the hinge. To prevent damage to the ball joint, the condition of the rubber protective boot should be monitored. It is advisable to do this on an overpass or inspection hole.
In order for ball joints to last longer, you need to drive carefully on broken road surfaces and change damaged boots in a timely manner. Do not forget that any vehicle mechanisms and components require regular maintenance and repair. You can learn more about replacing ball joints in this video.
This is interesting: How to change a Duster low beam bulb
How does it work?
As you understand, a closed “ball” can rotate in any direction, even spin. A fixed mount is attached to the cylindrical body, which is installed in the necessary suspension elements - this part is not movable. But the upper threaded pin is attached to the moving parts, thanks to which they can turn or even rotate.
In old rear-wheel drive cars, for example our VAZs, there were about 3 ball joints. Two were located in the burdocks and allowed the caliper to rotate along with the wheel. One was located in the steering rod and pushed the wheels.
The MacPherson suspension has greatly simplified the design. Here, as we know, there is a support bearing and it allows the strut and caliper to rotate, but the ball joint remains at the bottom. There are also steering links that push the calipers, causing the wheels to turn. There are only two ball joints here.
It is also worth mentioning that there are options with four supports, but they are quite rare and should not be considered.
Now there may be objections - that the ball joint and the steering tip are not the same thing. Guys, the only differences are in the mounting of the case, the essence of the work is the same.
If we summarize the work, the following comes out: you turn the steering wheel, the force passes through the steering rack to the caliper, and in order for it to turn, hinge joints are needed, this is exactly the work that the supports, steering tips and, of course, the support bearing do.
An important component of a car suspension
The ball joint performs functions that are important for its comfort and safety in every car. It is a suspension element equipped with an iron rod with a ball-shaped tip on one side and a thread on the other end.
The configuration of this part requires the presence of a special casing into which polymer filler can be poured. The casing must have a hemispherical receiving part for attaching the ball part of the pin.
Causes and consequences of ball joint failure
As mentioned above, the support was invented as a replacement for the pivot, but getting rid of it did not get rid of the forces acting on the hinge. If you ask an almost philosophical question: “So why do ball joints wear out?”, then the answer will consist of three main points (there is also a fourth - time - but it is not interesting, since it is understandable).
First: increased shock loads on the suspension when driving, for example, along tram tracks at indecent speeds or normal vehicle operation in unusual road conditions, which will not surprise us. Second: lack of lubricant where it should be (remember the grease fittings?). And finally, third: destruction of the support boot.
As for the design features of suspensions and the effect of this on wear, we can say the following: any ball joint, no matter how it is installed - on the lever or on the steering knuckle - will wear out due to shock and friction. And if you want to save money and nerves, then you need to look behind the wheel more often, and also not shout “Banzai” to yourself when you see approaching misunderstandings in the form of potholes.
Checking the condition of the hinge
For diagnostics, it is best to use a lift or inspection hole. The wheels are hung out, the surrounding area is illuminated with a good light source. To increase the applied force, use a pry bar inserted between the steering knuckle and the lever. The presence of even a slight play indicates a defect in the sealing liner and an increase in the gap.
How to check a ball joint using this method - in the video:
A less common way is to measure the distance between the base and the finger . This is possible if the shell has a hole for an oiler. The car is driven onto a flat area above the inspection hole, and the plug (oil nipple) is unscrewed. Determine the distance from the rod to the lower plane of the body. In the new spare part it is 11.8 mm. For measurements, use a caliper or a bore gauge. This method is suitable for serviceable hinges where there is a service hole for an oil nipple.
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Ball joint repair
There are several repair methods. Often, the ball joint is replaced with a new one. Replacing a support along with a lever on most foreign cars is a very expensive pleasure, since the price of one lever is not a small amount, and there are also cars that have complex multi-link suspensions (up to 5 on one side only). The cost of the work performed will also be quite high for the lower lever, and twice as much for the upper one. Therefore, the services of restorers who repair even those supports that are replaced in the assembly with a lever are in great demand.
Restoration is much cheaper than purchasing a new part. This is especially noticeable for supports that come complete with arms. Various technologies can be used to restore them.
- The easiest one is to convert the ball joint into a collapsible one, change the plastic inserts and polish the pin.
- A somewhat labor-intensive technology - the housing is filled with liquid polymer under pressure. Next, this polymer hardens in the gaps. The pressed supports into the levers are first removed and then replaced with non-original supports.
Remember that such savings may cause troubles on the road; to avoid this, it is recommended to use new components.
Fixation on the steering knuckle
If the support is located on the lever, then it can be attached to the steering knuckle. Such features are typical for a ball-on-lever. The design can have three options:
- the threaded pin is connected and secured with a nut, which must be cottered;
- for fastening, a self-locking nut is used, which has an internal locking ring;
- a pinch bolt is installed, which is rare, for example, on the Hyundai Santa Fe since 2006.
The last point is less acceptable, since if it breaks and needs to be replaced, it may turn out that the threads have soured. A negative factor is the need for a special wedge used to release the ends of the knuckle bracket where the ball pin is fixed. Sometimes even in the wonderful suspension designs of German cars, stuck bolts create many difficulties during disassembly. The situation cannot be saved by heating the fist or freezing the bolt. Even a ten-ton force from a hydraulic press does not allow the bolt to be pressed out. Owners of an Audi A6, for example, have to part with amounts equivalent to $400-500. In some cases, engineers move the hinge to the steering knuckle from the lever. Although such a solution does not add maintainability. Then there are several ways to fix it:
- bolting;
- pressing;
- in the knuckle bracket the use of a coupling bolt.
In each case there are both advantages and disadvantages.
What causes system failure
As a rule, system replacement is required in the following cases:
- boot rupture;
- driving on poor road surfaces;
- lack of the required amount of high-quality lubricant;
- grinding of the finger, which occurs along with an increase in the gap and loosening of the element.
On average, the service life of a support reaches 30-100 thousand km, so it is difficult to call the element durable.
