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What, how and why

AUTUMN FATIGUE

In the next 10 years, the Lada is unlikely to disappear from our roads. And with them, and typical damage.

Victor SLESAREV

Whoever has not seen such a picture is standing, with a frowning glance, a “Zhiguli” with a “broken” wheel. And if there were no serious consequences for the crew or others, it can be considered lucky.

Usually they say - "the support is over." They mean the lower ball - one of the notorious weaknesses of the front suspension. The design is such that when you hit a wheel from below (say, in a road pothole), the support pin tends to push the edges of the hole in the body and break out. This is especially familiar to motorists driving on bad roads.

The material, experts say, gets tired, cracks develop in it. First imperceptible, later clearly visible. True, provided that the owner wants to see them: this is a troublesome business! The ball joint is hidden by a rubber cover, which without removing the bolts can not be removed. Nobody will do this for nothing. And the dirt does not add enthusiasm, as well as the fact that it is difficult to inspect the support without removing the wheels.

In other words, a rare car enthusiast will explore the pillar before it collapses. But in vain! If the support was considered “new” five years ago, then it is worth at least checking its wear, as shown in Fig. 1. Unscrew the screw plug from below - and measure the distance S with a depth gauge. If it reaches 11.8 mm, it is time to throw out the support - it is in a pre-emergency state. When hit, the upper hinge body can “open” along the cracks like a flower - and the ball will fly out!

The result is in fig. 2. The wheel, together with the steering knuckle, “folds” like the chassis of an airliner and goes deep into the front wing. Pray that this does not happen at a speed of 100 km / h!

The danger prompted the creation of reinforced supports, which are many on the market today. Some are better, others worse - this is an independent topic, which is sometimes discussed in the magazine. But - let's say! - the most luxurious ball bearings were presented to the battered "Zhigulenka". Solved the problem of suspension strength?

Not at all! Other elements may fail. After all, the suspension of FIAT-124, the “progenitor” of the Lada, was clearly designed for much simpler operating conditions, besides, Italians would never have thought of operating a cheap car for 20-30 years. The ball bearing on the lower arm is only one of the weak links of a rather long chain.

On a photo 1 and 2 - the lower lever of a forward suspension bracket. The locations of possible cracks are shown. The most “famous” - both in the number of cases and the possible consequences - is the rather “flimsy” end of the lever, to which the ball bearing is attached with three bolts. Fatigue cracks are common here. It would seem that prevents the owner of the car from watching this place? However, again you have to lift the car with a jack, remove the wheel, thoroughly clean the lever around the support from dirt and lose a lot of time on this, get dirty … But cracks, maybe not! I tried in vain! After such a “failure”, the touchy car owner forgets about leverage for a long time. Sometimes - before the accident.

Fatigue cracks can appear both near the eyes for silent blocks, and in the middle part: although the lever is different in different areas, it is heavily loaded! To see these cracks in time is the same as canceling an “order” for an accident. An experienced "Zhigulist", drove into the overpass or pit, regardless of purpose, be sure to inspect the suspension details. Sometimes a characteristic strip of rust impregnates a crack, impregnating a thin layer of dried mud. You can also try this technique: pouring the lever over with diesel fuel, wipe it dry and, having applied a layer of liquid clay, inspect the dried one after a few days. Diesel fuel, penetrated earlier into the cracks, "appears".

As you can see, the main thing in this business is meticulousness! And what threatens the breakdown of the lever? If this is a classic separation of its end with a support, then the result is the same as when a ball was pulled out of a support: “cleaning the chassis”!

If the lever breaks near the silent block, for example in front, the result is different. Now the wheel is badly “heading”, deviating to the side at the first push from the road bump or during braking. Good, in general, is also not enough. At high speed, you can suddenly find yourself in the oncoming lane, in a deep ditch, in an embrace with a pillar …

But do the upper arms break from fatigue? Unfortunately, yes - despite the simpler working conditions. After a thorough experience, cracks can be found on them, both in the main “body” and in the amplifier shelf, abutting against the suspension buffer.

We started the conversation with the most famous breakdowns. But this is not the end of the matter. Quite often, the Lada collapses the basis of the front suspension - the transverse beam ("cross member"), on which, resting on the elastic supports, the engine stands proudly. The beam connects the left and right side members with the mudguards. In a word - an important detail working in conditions of complex variable loads.

The ends of the transverse beam are connected to the side members (Fig. 3) through bolts: three on each side. Two short, vertical ones are wrapped in nuts on the lower shelf of the side member, and a long, horizontal one, presses the “cross” ear to the side wall of the side member (photo 3). Here we also show a possible crack. On older machines, she often cuts the “ear” - and the beam hangs only on two vertical bolts.

Sometimes the car enthusiast sees that the crack has already spread 1–2 mm, but continues to drive, although the car must be repaired immediately. If the beam is sagging, then not today or tomorrow, bolts with nuts will burst from the dilapidated lower shelf of the spar. The engine will tilt, the lower lever axis will drop, the wheel will get a negative camber and … come!

Repairing such a machine is not an easy task. Usually in this case the car is very worn out, the body is corroded by corrosion. You ask the master to replace the mudguards with the side members, and he asks in response to what kind of hardware you intend to weld them to. Around - one rust.

In some cases, the crossbeam breaks in the middle, at the “waist”. After that, its halves, loaded with an engine and lower levers, begin to live their own lives - swing, deform spars, break them. And, ultimately, destroy other body parts in the engine area.

However, on the go, at high speed, another failure of the beam is more dangerous - near the bolts of the axis of the lower arm (photo 4). Fatigue does its dirty work: invisible to the car owner, cracks grow in the “box” pulled together by bolts, more often ahead. The bolt remains in place until the fatal shock in the pothole. Sometimes it’s enough to brake so that the lower lever easily rips the bolt out of the “rotten” cross-beam, deviating to the side with the wheel (see Fig. 4). Here try to keep the car on the set course … Did you succeed? You were lucky.

In general, the crossbeam can be repaired quite well by welding - in the era of scarcity, they did so. But the welder must be sensible in order to return the beam not only strength, but also the drawing dimensions. Otherwise, after repair there may be problems with the geometry of the front suspension.

Of course, other details also break down: springs, anti-roll bar, etc. A “cramped” spring gives itself out as a “drawdown” of the machine, and a collapsed stabilizer - by large rolls on bends, often by an unambiguous rattle. Of course, shock absorbers are far from eternal. If someone entertains you with tales about their impeccable condition after a 100, 000 run, do not react. The shock absorber, having “built up” on bad roads, even to 15–20 thousand km rarely preserves even half of its former characteristics. Here is the time to recall that eternal machines do not exist.

Fig. 1. Check the degree of wear of the ball joint. Control size: S = 11.8 mm.

Fig. 2. So (schematically) the wheel “folds” when the ball joint or the place of its installation on the lower arm is destroyed.

1. The lower lever of a forward suspension bracket. The places of possible cracks near the eye are indicated by arrows.

2. A crack is also possible in the area of ​​attachment of the lower ball joint.

Fig. 3. Scheme of fastening the transverse suspension beam to the spar.

3. The “ear” of the crossbeam often cracks in the location shown.