Domestic roads often can not boast of a smooth and even surface. In order to smooth out the movement of the car on a rough road with pits and potholes, suspensions were invented, which are now used everywhere in cars. Suspension elements are closely connected with the body, a pair of front and rear wheels and are able to reduce the level of vibration when driving on uneven road surfaces.
Regardless of the type of suspension, it always performs the same function. However, there are several types of suspensions and it is necessary to understand the features of each type of suspension. Many experts are convinced that sports cars one type of suspension should be used, and on compact cars another type of suspension should be used.
Rear suspension elements
Each suspension element has its own design features, if you disassemble the suspension into its component parts, then each suspension has:
- extinguishing device;
- stabilizer;
- various fasteners;
- support and guide element;
- elastic element.
Each listed element can perform several functions at once. So, the spring is considered both a shock absorber and an elastic element. Modern cars come with complex suspension systems, where each element performs a separate function and, in combination, reduces the level of vibration when driving on uneven road surfaces.
Elastic elements are closely related to the car body, this includes springs and springs. These elements in most cases have the same diameter. And springs with different diameters play the role of elastic elements variable hardness. In the center of each spring there is a bump stop, when the spring is fully compressed, this element allows you to smooth out the effect strong vibration. Each suspension has several springs, which are springs various lengths. There are several types of springs - leaf springs, spring and torsion bars.
Torsion springs are made in the form of tubes, inside each tube there are rods. They are in a dense ring of shock absorbers. Hydropneumatic and pneumatic elements can also be attributed to torsion springs. The hydropneumatic element is a gas cylinder that rises or falls during the movement of the car.
The distribution elements of the suspension are designed to evenly distribute the wheels relative to the body, they fix the suspension. The distributing elements are made in the form of levers. The shock absorber is made in the form of a metal tube, it allows you to dampen vibrations when they occur when the car is moving on a rough road. Shock absorbers can be made in the form of a single or double tube. The shock absorber actuation system may be different.
Rear suspension types
The rear suspension elements are fastened by rubber-metal bushings and ball bearings. On the sides, the load on the turns is evenly distributed due to the bar. It fixes the levers of the wheels and is presented in the form of a stabilizing element. roll stability. Suspensions in cars are found dependent and independent.
In a dependent suspension, there is a rigid beam that tightly aligns opposite wheels. When one wheel changes its position, the position of the second wheel also changes. The dependent type of suspension has long been used in the automotive industry. Initially, in this type of suspension, instead of elastic elements, springs were used, now they are more often replaced by levers. The dependent type of suspension has several important advantages.
Firstly, this type of suspension is lightweight, with this type of suspension it is convenient to move on the road with ruts. Secondly, the dependent type of suspension has a high transverse center. This type of suspension is characterized by the fact that it allows you to move comfortably on any type of road. However, skidding is difficult to avoid in dependent-suspension corners.
If, when driving a car with dependent suspension, an obstacle appears in front of only one wheel, then traction with the roadway drops. dependent suspension in the back of the car can be most often found on SUVs and trucks. And for independent suspension characterized by a more complex structure. There is no relationship between the wheelbase and the body with independent suspension. In such a suspension there are trailing arms.
The rear wheel of the car is attached to the lever, the levers are attached to the hinges, and they are attached to the car body. while the effect of parallelism of the wheels is achieved due to the strong trailing arm. Bushings in the suspension dampen shocks, and the car leans along with the wheels when cornering.
In this case, the roll center is parallel to the road. When using this type of suspension in a car, you can overcome any obstacles, but it is recommended to slow down before turning.
Torsion-link suspension
IN modern cars quite often there is such a type as torsion-lever. This type of suspension combines the qualities of the two types of suspensions described above. The torsion bar in a torsion-link suspension plays the role of an elastic element. It is attached to the frame from one end, and from the other end is attached to the driving element. The design provides a place for a beam that works under pressure. The torsion bar can be made with a round or square section. This type of suspension is compact and easy to use on small cars.
MacPherson is another type of common suspension, such car rear suspension widely used in automotive industry. Such a suspension can be created for the front and rear wheels. There is a large distance between the support nodes in such a suspension, which is significant advantage. This suspension design is more suitable for smooth roads. On bumps with MacPherson suspension, shocks are strongly felt. Also, all types of suspensions are divided into single-lever and multi-link.
The car is equipped with a suspension in order to soften the blows at various jolts when driving. Rear suspension performs the function of damping vibrations that are transmitted to the rear wheels when driving. Since most cars today are front-wheel drive, the rear suspension is less complex than the front. After all rear wheels do not turn while the car is moving, therefore, no complex components and systems are required that provide stabilization when the wheels turn. However, the car also has its own characteristics, which are worth reading when operating the car.
The most common type of car suspension is the torsion bar suspension system. Devices for directing the suspension axle to the body are two longitudinal arms. They are interconnected by a special elastic connector.
What is the rear suspension made of?
These trailing arms are made of metal pipes. This allows you to achieve the desired structural strength. They are welded to the connector, and together they form a beam, which is hinged on brackets to the car body. In each lever on the front part is equipped with a bushing. A rubber-metal hinge (silent block) is pressed into it. Through this hinge, fastening to the beam is carried out using a bolt and a lock nut. Behind these levers there are lugs for attaching shock absorbers.
Springs are also installed in it. They are made of durable round steel. The lower end of this spring rests against a special cup on the shock absorber, and the upper end against the ledge on the body. Between the spring and the upper stop, a special gasket is installed for rubber insulation.
In addition, a protective cover is put on top of the shock absorber, which prevents dirt and dust from getting on the shock absorber and stem. This casing has a corrugated shape, which allows you to change the length during the course of the car. The axle of the rear wheels is attached to the flange of the suspension arm. For this, four bolts are used. At the same time, these bolts are attached brake mechanism. The rear suspension mainly uses a telescopic hydraulic shock absorber, which is a double-acting type. This allows you to achieve the smoothest possible movement of the car in cases where the rear wheels hit bumps or obstacles.
There is a damping of the movement, thereby the comfort when driving increases. In addition, it must be taken into account that in the event of extraneous noise or knocks in the rear suspension, it is necessary to carry out diagnostic measures. If a defect is not detected in time, this will not only cause a deterioration in the smoothness of the car body while driving, but over time it can damage some of its elements. Therefore, you need to pay attention to the appearance of the first signs. unstable work rear suspension mechanisms.
Multi-link, independent. It is a rather vulnerable element in Focuses, as it contains 8 levers and 14 silent blocks.
If over time your suspension starts to rumble, a slight wobbling of the stern appears when driving, then this article is for you.
Figure: Screenshot from the program for the selection of spare parts, suspension Ford Focus 1 and 2. it shows all the main rear suspension arms. The diagram shows:
5A638 - trailing arm silent block, 5500A bone lever, 5500b - sickle lever, 5K652 - large transverse lever, HB1 - mounting bolts (8 pcs in total), HB3 - silent block bolt (4 pcs.)
5500b is a sickle-shaped lever, on a sedan and station wagon they differ in shape (in this diagram, a lever for a station wagon is drawn).
The arrows indicate the camber bolt, nut and washer, which must be changed each time the lever is removed (if this is not done, then it will not be possible to set the desired rear wheel alignment angles in the camber stand).
5A638 - silent block of the rear trailing arm, as a rule, requires replacement along with the levers. It is fastened with HB3 bolts, which are supplied only in the original (with variable thread).
5500A is a small wishbone, the so-called "bone". These levers are perceived heavy load, I recommend installing the original, Febi, Lemforder or Meyle.
Figure - sickle rear suspension Ford Focus 1, 2 (sedan and hatchback)
Sickles on the station wagon
On cars in the station wagon, sickle-shaped levers of a different shape were installed from the factory, this is done due to the fact that in the station wagon there is more load on the trunk, and when maximum load trunk on large pits could be blows of a standard sickle-shaped lever on the body. The wagon's sickle-shaped levers are shaped like a banana. When buying station wagon levers, you can buy standard levers from the sedan and hatchback, because the "banana" levers are more expensive and less choice, these are either Chinese levers or expensive original ones. Standard "sickle" levers are cheaper good analogues. As practice shows, messages from forums and so on, standard "sickles" from a sedan are easily installed on a station wagon, and this does not lead to any shock or wear.
Figure - Sickle-shaped lever station wagon "banana"
On Ford Focus 2 cars, two rear suspension options are installed.
First suspension option(straight arms) is the same as the Ford Focus 1 suspension, has straight spring arms. Straight levers are original and non-original.
Drawing - Straight arms (Original Ford number: 1357317)
Drawing Direct levers on a car Focus 2
On the "straight" levers, the stabilizer bar "hairpin" (1719542) is installed.
The second version of the suspension is distinguished by spring-loaded levers - they are "bent" there. According to statistics, such levers occur in 1 out of 10 cars. The levers are only original. You can put levers from Mazda 3, they are exactly the same, they even have a FoMOCo stamp on them.
Also, the suspension with "bent arms" has a different type of stabilizer strut. In order to determine what type of suspension is installed on your car, it may not be enough to look at the VIN number in the catalog - in most cases it is not visible what kind of rear suspension arms you have.
To determine which levers (the first or second option) are on your car, you need to approach the car from the side exhaust pipe, look under the bumper and look at the spring arm on which the spring is installed. If it is straight, then you have the appropriate suspension and stabilizer bar - a hairpin. If the lever is "curved", then the stabilizer bar is g-shaped.
Figure - Rear transverse "bent" arm ( original number Ford: 1548460)
Features of replacing rear suspension arms.
In total, the Ford rear suspension has 6 levers replaced during repair - 2 "bones" 2 "Sickle" and 2 "under the spring". Most often they wear out at the same time, backlashes appear in each of them. Then they are changed all together, but there are exceptions, you can change "bones" or "sickles" separately, for example.
Signs of a malfunctioning Ford Focus rear suspension.
Symptoms indicating a malfunction of the rear suspension - firstly, this extraneous sounds, secondly, this is the yaw of the rear of the car while driving, and of course, when viewed at the service station, you can see the state of the silent blocks and the suspension as a whole.
Non-original details.
If you find out what you have, then you can purchase a Focus rear suspension kit for reasonable price. If the lever is "bent", then you can only purchase such a lever original (Bone and sickles can be bought while not original).
A complete set of Ford Focus rear suspension is produced by several companies. Mapco, Meyle, Ruville, Teknorot and others rarely found in St. Petersburg suppliers.
Mapco (Chinese Germany, a budget option, there are two versions - with a set of bolts, part number 53612/1 and without a set of bolts 53612).
Drawing - set of levers for Ford Focus, Mapco 53612/1
Drawing - .
The second company is Meyle, made in Germany, the quality is good.
There is a Ruville kit (935259S). It is more expensive, but in addition to levers and bolts, it also includes two additional fist silent blocks ("butterflies"), which also always change.
Drawing - rear suspension kit Ford Ruville 935259S
(Please note that the kit includes "butterflies" silent blocks and shock absorber bumpers)
REAR SUSPENSIONDEVICE FEATURES
The rear suspension of the car is dependent, includes a guide device, elastic elements and devices that dampen body vibrations.
Rice. 4-30. Rear suspension: 1 - spacer; 2 - rubber bushing; 3 - lower longitudinal rod; 4 - lower insulating gasket of the spring; 5 - lower support cup of the spring; 6 - compression stroke buffer; 7 - bolt for fastening the upper longitudinal rod; 8 - bracket for fastening the upper longitudinal rod; 9 - suspension spring; 10 - upper spring cup; 11 - the upper insulating gasket of the spring; 12 - spring support cup; 13 - thrust lever drive rear brake pressure regulator; 14 - rubber bushing of the shock absorber eye; 15 - shock absorber mounting bracket; 16 - additional compression stroke buffer; 17 - upper longitudinal rod; 18 - bracket for fastening the lower longitudinal rod; 19 - mounting bracket transverse bar to the body; 20 - rear brake pressure regulator; 21 - shock absorber; 22 - transverse rod; 23 - pressure regulator drive lever; 24 - holder of the support bushing of the lever; 25 - lever bushing; 26 - washer; 27 - remote bushing
Guiding device. Beam rear axle it is hinged to the body with the help of torque rods: two lower 3 (Fig. 4-30) and two upper 17 longitudinal and one transverse rod 22. The longitudinal rods transmit pushing and braking forces from the drive wheels through the rear axle beam to the body. the transverse bar keeps the body from lateral displacements. The reaction rods are attached to the body brackets and the rear axle beam through rubber-metal hinges, which are structurally the same and differ only in size. The hinge consists of a rubber bushing 2 installed in the eye of the rod, a spacer sleeve 1 that passes through the hole of the rubber bushing, a thrust washer and a rod fastening bolt.
The elastic elements of the suspension consist of coiled coil springs 9, two main buffers 6 of the compression stroke and an additional compression buffer 16. Springs under a static load of 295 kgf are sorted into two groups A and B. The groups are marked similarly to the front suspension spring groups, i.e. group A - yellow stripe, group B - green. The spring mounted on the suspension rests with its upper end on the support cup 10 through the rubber insulating gasket 11, which is placed in the stamped steel cup 12 of the body. The lower end of the spring rests in the cup 5 of the rear axle beam through an insulating plastic gasket 4. The main buffers 6 are installed inside the springs and secured with a mushroom nipple in the holes upper supports 10. Additional buffer 16 is mounted on a bracket bolted to the bottom of the body.
The extinguishing device consists of two hydraulic shock absorbers, the device of which is described below.
REMOVING AND INSTALLING THE SUSPENSION
Withdrawal. Raise back vehicle and place on stands. Remove rear wheels.
Disconnect cardan shaft from the flange of the final drive gear.
Disconnect the hydraulic brake hose from steel tube installed on the axle, and take measures to prevent leakage of fluid from the brake system.
Disconnect the rear cable bracket from the body parking brake, remove the front cable return spring and, by unscrewing the locknut and adjusting nut, release the rear cable branch. Disconnect the rear brake pressure regulator drive link from the bracket on the axle beam. Disconnect upper ends shock absorbers.
Place a hydraulic jack under the rear axle beam. Disconnect the longitudinal and transverse rods from the brackets on the body, lower the jack and remove the bridge.
Proceed to disassembly of the suspension:
Remove the shock absorbers from the brackets on the axle beam;
Disconnect the longitudinal and transverse rods from the brackets on the bridge beam.
Details of a back suspension bracket are shown on fig. 4-31.
Installing the rear suspension is carried out in the reverse order of removal.
At the same time, install class A springs on the suspension (with yellow marking), in exceptional cases, when there are no springs of this class, it is allowed to install class B springs (with green marking).
To prevent damage and over-tightening of the elastic bushings of the hinges of the rods and shock absorbers:
Load the rear of the vehicle so that the distance from the axle beam to the body side member, measured at 100 mm from the cross bar bracket (Fig. 4-32), is 125 mm;
Tighten torque wrench nuts on the bolts for attaching the longitudinal and transverse rods, as well as on the pins for attaching the shock absorbers to the axle beam and to the body.
CONDITION CHECK
Wash all parts thoroughly before checking.
Rubber parts, bushings and protective coatings protect from solvents when washing.
Springs. Check the elastic characteristic of the springs at the control points (Fig. 4-33), having previously compressed them three times until the coils touch.
Note. According to the length under load of 2950 N (305 kgf), the springs are divided into two classes. Class A - length more than 273 mm and class B - length less than 273 mm. Class A springs are marked with yellow paint on the outside of the coils, and class B with green paint.
Rice. 4-31. Details of the rear suspension: 1 - lower longitudinal rod; 2 - rubber bushing; 3 - bracket for attaching the lower longitudinal rod to the body; 4 - spacer sleeve; 5 - upper longitudinal rod; 6 - additional compression stroke buffer; 7 - spring; 8 - upper spring cup; 9 - compression stroke buffer; 10 - upper isolating spring gasket; 11 - shock absorber; 12 - lower insulating gasket of the spring; 13 - cross bar
Rice. 4-32. Rear suspension installation diagram: 1 - body spar; 2 - cross bar bracket; 3 - rear axle beam; X=125 mm
Rice. 4-33. Basic data for checking the rear suspension spring
Check for spring deformation. If the spring elasticity does not match the data (Fig. 4-33) or deformations can cause the spring to malfunction, replace it.
Check up a condition of rubber basic linings of springs; if necessary, replace them with new ones.
Rods. Check:
Are the rods deformed; if possible, straighten them;
Are there any cracks on the brackets of the rear axle beam and body; if cracks are found, repair the brackets;
The condition of the elastic bushings of the rod hinges; if necessary, replace them with new ones using tool kit 67.7820.9517.
The suspension of vehicles with front-wheel drive is mainly semi-independent on the rear wheels on an elastic "P" - shaped beam.
The rear device is shown in the figure.
Simplicity of design;
High rigidity in the transverse direction;
Small weight;
Possibility to change the characteristics by changing the geometry of the cross section of the beam.
This system also has disadvantages:
Suboptimal change in camber;
Special requirements for the geometry of the bottom of the car at the attachment point.
rear beam
Independent rear suspension device
To improve the handling of cars and increase comfort, an independent rear rack is often used on racks with longitudinal and wishbones. Its device is shown in the figure.
Independent suspension
This design has the following advantages:
Relative simplicity of design;
Small weight and cost;
Improved camber and toe-in characteristics during operation.
Along with the advantages, this scheme has disadvantages:
Limited limits for initial camber setting;
Increased processing noise road bumps due to the location of the pillar supports directly in the body.
Multi-link rear suspension
On cars of medium and higher classes, which involve high level driving comfort and improved handling use a multi-link rear. One such design is shown in the figure.
Multi-link suspension
It has the following advantages:
Possibility of ensuring optimal wheel alignment angles during operation;
The possibility of improving the comfort of movement;
Reduced noise and vibration transmitted to the body.
The disadvantages include:
High manufacturing cost;
High labor intensity of maintenance and repair.
By using an independent multi-link rear suspension, designers can ensure that both camber and toe-in are optimally adjusted when cornering.
A properly selected combination of rigidity of the rubber elements can provide the effect of the so-called "steering". This term refers to the individual change in the convergence of the rear wheels under the action of centrifugal force which compensates for side slip of the wheel.
Unfortunately, the development of such a design requires a large amount of experimental design work and, accordingly, significant costs. That is why multi-link suspensions not widely used on small and medium-sized cars.
