CLUB OF CAR FANS
FROM THE PRACTICE OF “KOSTOPRAVA”
The car body in case of accidents suffers first.
What should be borne in mind when deciding on a repair?
The body, as you know, the most time-consuming to manufacture and expensive part of the car. It is he who primarily suffers from car accidents, even, at first glance, minor, forcing the owner to spend large sums on its restoration. Note: even masterfully mastering driving techniques, none of us is safe from these troubles. Therefore, it is useful for everyone to know what happens to the body as a result of an accident, what should be paid special attention to, etc. This will help to get out of a difficult life situation with minimal losses.
The supporting (most often, all-metal) body combines both the power functions of the frame and the protective ones of the body itself. Its main material is a steel sheet 0.6–2 mm thick. Bearing elements - racks, spars, crossbars, sills and others - are box-shaped. Together with the outer and inner panels, they provide the necessary rigidity.
For all the variety of car brands, there is much in common in the structure of their bodies: various wings, spars, struts, mud flaps, etc. are quite traditional, as well as their purpose. In fig. Figure 1 shows a schematic diagram of the location of power elements, and the table shows the most important control parameters of VAZ body parts.
The body is deformed not only in an accident. Energetic driving on rough roads, for which the car, strictly speaking, is not intended, as well as overloading the car, corrosion, fatigue of the material of power parts and panels, are ruining it.
This is true for foreign cars, not to mention ours. And here in the "foremost" products from AZLK, although other plants should be given credit! How "rot" VAZ cars, especially VAZ 2101 … 2107, has long been known. But the appearance of the “forty-first” at one time deprived them of the dubious palm. According to my tinsmith, observations, the body of this machine combines low strength and rigidity with poor coloring, useless anti-corrosion treatment and anti-gravel protection of the underbody and wheel arches. Machines with the same defects constantly come to us for repair. These are fatigue cracks in the area of the front suspension and the collapse of the thrust cups of the front struts inward.
The bodywork of the front-wheel drive VAZs (it is too early to talk about the "tenth" series) has its own characteristics. The front end of them - it is well known to car owners who were in accidents - is durable and tough. But … the interior is weak! Even the two-door "eight" is no exception. That is why exceeding the passport carrying capacity of these machines - 425 kg - is very dangerous.
… So - the accident. We, repairmen, divide them into three categories: only one part is bent; several details are deformed, but there is no significant skew of the body; the whole body is very skewed.
The deformations themselves depend on many factors: the speed and direction of movement of each of the participants in the accident, the model of the car, its load, condition, etc. Entrust its inspection to a specialist. But be on the lookout: an unscrupulous master can intentionally overestimate the complexity of the work. It happens, so much so that his provocative offer to buy a car for a song you will perceive as salvation! It is useful to show the car to several tinsmiths and compare their conclusions.
What parts of the car in an accident get the most, according to Fig. 2. Everything is logical: most often they beat the front and the stern. Less often - the left side: the driver takes care of himself, and the feeling of size is better here (rollover and some other consequences of accidents are not considered here).
To assess the degree of damage to the body, tinsmiths use simple but reliable techniques, which are also useful for motorists to know about.
First of all, a thorough, thoughtful inspection. By the size and uniformity of the gaps between the parts, it is possible to draw preliminary conclusions about what the body survived. Say, a change in the clearances of the front wing of the Zhiguli suggests its displacement and possible deformation. But the wing is connected with other details - the front panel with the hood, the spar splash guard, the front door pillar, which could also bend when hit. In addition, the metal, even warped, is still resilient, as a result of which the details are “taut”. (If during the repair cut the connection between them, then the details will shift relative to each other.)
When hitting the front or rear of the car, as a rule, door openings warp, or even a crease on the roof appears - near the middle pillar: the "excess" metal needs to be removed somewhere. In such cases, it is best to repair the car on a special stand for dressing bodies.
If the gaps between the parts of the plumage that have not undergone a direct impact have changed, then the internal power elements to which these parts are attached are bent or shifted. It will require accurate measurements of the geometry of the body.
As a rule, a strong blow is accompanied by local folds, swelling, “creases” of the strength elements, delamination of the welds. Even without knowing the existence of such a science as “sopromat”, an experienced master tinsmith will accurately indicate where to look for the greatest deformation - in the places of bending of the side member. Of course, the flat parts welded with it in these places will also bend.
After the accident, the position of the windshield and rear windows in the openings indicates the geometry of the body. If there are cracks between the gum and the body, and even more so, the glass with one edge jumped out of the seat, the skew is obvious.
Signs of deformation are found not only near the place of impact. Unlike many foreign cars, where, for the sake of passive safety, shock absorption zones are provided that protect the interior, the spars of our cars easily bend the engine shield, the front of the floor, distort the front door rack and roof, ultimately the whole body. Upon impact, the front spar usually rises, thereby causing a longitudinal twist of the body. Therefore, when inspecting a beaten car, the condition of the corners distant from the place of impact is examined in depth, and even with the slightest doubt, they even dismantle the trim in the area of possible deformations.
Otherwise, the consequences of a side impact. Side zones of the body are very malleable and the consequences of such accidents are extremely dangerous. The power circuit here is similar to an inverted “T” (see Fig. 1) - the longitudinal floor spar (threshold) is connected to the central roof pillar. The impact of the bumper of another car in this zone falls above the threshold, which is why the rack bends and moves inside the body. Its upper point drops - and since the stiffness of the roof sheet is small, the pillar connected with the threshold pulls the roof down - a characteristic failure appears in the middle part.
Such a blow is possible when the threshold bends inward, collecting the floor in folds. The front and back of the car are pulled towards each other, and the beaten side is shorter than unbroken. Finally, the impact can be so strong that the deformation of the floor and roof reaches the opposite side, causing the external pillar to bulge out. Restoring such a body is the most difficult and costly job.
A separate conversation about the hitch! They say that it protects the back from a blow from behind. Alas, everything is much more complicated. In many cases, when it was possible to get by with "little blood", replacing only the rear panel, the coupling devices played a cruel joke with the owners, passing the blow right into the zone of the rear axle tunnel! The cost of body repair then rises sharply. In my practice, there was a case when the “nine” with a towbar was hit from behind by another of the same, but without a towbar, and that one got from the hitting Volga. The first one suffered the most - thanks to the coupling device!
ROULETTE CHECKING EYES
When studying body deformation, it is important to carefully measure the openings. By the way, ordinary roulette gives acceptable accuracy. We measure the engine compartment and trunk - at the level of the hood and trunk lid, as shown in Fig. 3, and doorways - according to Fig. 4. If there is a fifth door, we control its opening in four directions (Fig. 5). The required dimensions and tolerances are given in the table. By the way, if it was not possible to find such data for your car, do not worry: the dimensions can be taken from another one, preferably new and not in an accident.
No less important is the control of the base points of the body - by the distances between the wheels. To eliminate errors, you should be aware of the possible deformation of the rims or suspension arms. At the same time, one should not forget another thing: if there are not enough regular adjustment methods for the correct installation of the front wheels, this can be a sign of serious distortions.
Now something about the repair itself. Suppose there is no point in restoring the body - and you decide to buy a new one. Keep in mind: sometimes artifacts made from repair parts get into stores. Issue their welding points. A characteristic trace of factory resistance welding is a round, well-known dent. A semi-automatic artisan in the place of welding leaves a bump. "Homemade" body in all respects worse than the factory.
If the direction of deformation at the moment of impact is precisely defined, then often the shape of the part can be restored by pulling it in the direction opposite to the impact. However, an acceptable stiffness of the part can be achieved only by completely removing the folds. It is not easy to achieve this in box designs, and a decent master will not heat the power part to a plastic state, so as not to weaken it, and therefore will replace it with a new one. Bypasses in the form of various linings, inserts, etc., although they provide rigidity, but make the machine heavier, and to maintain corrosion resistance are not always acceptable.
Regardless of the method of repair, the tinsmith must return the body to its original geometry, at the same time unloading those power elements that absorbed the impact energy, and restoring the bearing capacity of the body. Unfortunately, the quality of stamping parts that fall into stores is often such that the "golden" master tinsmith cannot afford to eliminate some defects.
In conclusion, a few words about the roof. They say that during its deformation, the body is not suitable for restoration. This is not true. The roof is just a detail. No one throws the body out because of a deformed threshold or spar. They are changing. Meanwhile, an error in the installation of the spar affects the stability and controllability of the machine, and a roof that is not very carefully repaired most often does not affect anything other than the appearance (less often, the door's tightness, etc.).