When it comes to the ball pin, it means the ball joint of the suspension of the car. However, this is not the only place where such a technical solution is used. Similar devices can be found in the steering, in the guides of the hoods of cars. They all work on the same principle, so the diagnostic and repair methods are the same.
Where are ball joints used?
The main place of application of ball pins is the connection of the steering knuckle with the suspension arms of the car. This solution allows the steering wheel hubs to change their position in the horizontal plane, while remaining stationary in the vertical.
Earlier, when cars used mainly dependent suspension, the role of pivot joints was given to pivots. They were massive and required constant maintenance: cleaning, lubrication. Then the pivots migrated to cars with independent suspension. Having a large resource, these nodes could serve the entire period of operation.cars. In this regard, the question arises: "What was the need to replace the pivots with ball bearings?"
The reason was that in addition to the fact that the ball pins improved the controllability of the machine, they did not require maintenance, unlike the pivots. But the cost of convenience was the frequent replacement of these elements. In fact, they have become consumables.
In addition, there are ball bearings in the rear suspension. They are used on vehicles with independent linkage suspension. This design allows you to change the position of one wheel on a rough road without changing the position of the other. Due to this, the machine remains more stable when driving.
In addition to the suspension, these nodes are present in the design of the steering trapezoid. There they play the role of movable tie rod joints. It is they who transmit the force from the steering mechanism, changing the angle of the steering knuckle.
At the dawn of its appearance, the ball joint was collapsible and was a hinge placed in a steel box. The diameter of the ball pin ranged from 7 to 25 mm. From below, the hinge was pressed by springs, and the body had the ability to change the lubricant during maintenance. With the introduction of polymers in the automotive industry, internal springs were replaced by elastic nylon inserts, inside which the hinge rotated. To make the support maintenance-free, its body was made non-separable, and the lubricant began to fill when installed under the rubber boot.
To date, almost all ball joints on passenger carsvehicles have become unattended. That is, they do not need to be lubricated during their lifetime.
Ball joint in car suspension
The ball joint pin is rigidly fixed to the suspension arm. There are several types of fasteners:
- Support screwed with three bolts or rivets. This variety is loyal to motorists. It can be easily replaced without resorting to the pressing method.
- Support integrated into the arm. This option requires either replacing the arm assembly or replacing the bearing and pressing.
There is also a kind of fastening of the support in the lever with the help of a retaining ring. This option is a compromise between the first two.
It is believed that the all-in-one option is a marketing move by car companies. Since the ball pin is a consumable item, changing it, you have to change the suspension arm, and at the same time the silent blocks.
Often craftsmen, in order to save money, changing the pin in a non-separable connection, weld the body of the ball joint to the suspension arm for rigidity. This should never be done for two reasons. Firstly, welding does not withstand the dynamic loads that occur when moving over irregularities, and secondly, when welding parts, a huge temperature arises that melts the plastic inside the part, and also changes the properties of the lubricant. The part after such fixation does not work for a long timewill.
The number of ball joints in the suspension depends on its design. The most common MacPherson strut suspension has one support on the side of each wheel. Whereas the double wishbone suspension includes upper and lower ball pins. This is due to the fact that in the MacPherson strut suspension, the strut support bearing takes over the function of the upper ball bearing.
The support is attached to the steering knuckle using a nut with plastic inserts that prevent loosening, or a nut with a cotter pin. There is a rarer mounting option, which is used mainly on business class cars, for example, the Audi A6. Here the support is fastened with clamping bolts. This fastening provides a more reliable connection, but at the same time creates problems during dismantling. This bolt often sours so much that it is not possible to remove it. Even with pressing. Therefore, in addition to the support, you have to change the steering knuckle.
Steering to the ball pin makes different demands than the suspension. If in the latter this element serves as a support and bears the weight of the car, then in the steering trapezoid it simply transmits the force that changes the angle of the steering wheels. Therefore, it is made in smaller sizes and has a different design.
From the side of the finger, this part is mounted in the bipod of the steering knuckle or in the bipod of the wheel struts (in the case of the MacPherson suspension), and the body is fixed to the steering rod with a threaded connection. The body itself has an elongatedshape with a long threaded part. This thread serves not only for fixing, but also for adjusting the toe of the steered wheels. Therefore, after replacing the ball pins of the steering rods, it is necessary to do the wheel alignment.
By type of construction, steering tips may vary. The tie rod ball pin itself is located inside either a one-piece plastic liner or inside a split metal one. Inside the tip, between the liner and the body, there is a steel spring that ensures that the liner fits snugly against the finger as it wears.
During operation, the ball studs are constantly exposed to the environment. To protect the part from dirt and dust, as well as to keep grease on the surface of the hinge, the ball joint is closed with a rubber boot, which is fixed with steel rings.
During operation, anthers may be damaged. This will lead to the inevitable failure of parts. Therefore, during each maintenance, it is necessary to inspect the rubber boots. Cracking is also unacceptable.
Causes of failure
There are several reasons why ball joints fail:
- Shock loads due to road roughness.
- Unnoticed in time torn boot. As a result, dirt, which is an abrasive, gets on the rubbing surfaces.
- Poor quality parts. The use of low-quality analogues leads to a quick failure of not only ball bearings, but also the suspension as a whole.
You can find out that it's time to change the ball joints or steering tips by the beating of the wheels. When driving through such an obstacle as tram tracks, you can hear the characteristic knocks emitted by ball joints, steering tips and silent blocks of suspension arms. To clarify what exactly is causing the knock, you need to hang out the steered wheels and shake them from side to side. If play appears when rocking in a vertical plane, then the ball bearings are worn out, if play appears in a horizontal plane, it means wear in the steering tips. Unfortunately, this backlash can only be eliminated by replacing parts.
Dismantling the support in the suspension
Depending on the design features of the car, the dismantling of the ball joint pin occurs in a different sequence. However, the principle is the same.
Let's consider the replacement of this part on the example of a car with MacPherson suspension. The replacement here is simpler than on a double wishbone suspension, because there is only one support per wheel. Sequence of actions:
- Hang the car on a lift. If it is not there, then jack up the car on one side, and then hang it on the goats, having previously installed wheel chocks and a parking brake.
- Unscrew the nut that fixes the support in the lever. If instead of a nut the ball joint is fixed with a clamping bolt, then unscrew it. Clamp bolts often stick, so before removing it, it must be treated with a penetrating lubricant. It happens that thisthe method also does not help, then it remains to heat the bolt with a gas burner.
- Disconnect the lower control arm from the subframe. This step is performed if the ball joint comes as a single unit with the lever.
In the case of fixing the support with a clamping bolt, the seat of the pin is unclenched with a wedge. If a suitable wedge is not available, it can be replaced with a bench chisel.
When the pin is tightened with a nut, the ball joint is removed with a puller.
It is installed on one side between the anther and the hole into which the ball pin enters, and the other side rests against the pin itself. Then, when the puller bolt is tightened, a force is created that pushes the pin out of the knuckle mounting hole.
What to do if a breakdown occurs on the road?
There are times when the ball pin needs to be changed on the road, but there is no puller. How to be in this case? Instead of a puller, you need to use a pry bar and a heavy hammer. After unscrewing the locking nut, insert a pry bar between the steering knuckle and the lower arm. The force must be applied in the direction of pushing the ball joint. At the same time, you need to tap with a hammer on that part of the steering knuckle in which the ball joint is fixed.
This method was often used when replacing ball pins VAZ-2101 - VAZ-2107, which often broke down on the road.
If the replacement of the ball pin occurs with the help of three bolts, with which it is fixed in the lever, then reassembly is not difficult. All the same steps are performed, only in reverse order. Also, the part is easy to change if it is fixed with a retaining ring. In this case, the spring ring is released, the old part is removed and the new one is installed.
If the ball joint is pressed into the seat, it is better to replace the entire lever. The reason is as follows. Even if it is possible to press a new bearing into the arm, the mounting hole will be larger than when it was originally installed. Therefore, the reliability of fixation will be less. How weaker the fixation will be, no one knows. Therefore, it is better not to risk it and install a new lever with support assembly.