Audi A4, S4

since 2000 of release

Repair and car operation

Technology of service, tool and workplace equipment

Technology of service

There are some techniques of performance of procedures of maintenance and car repairs on which the reader will find references in the text of the real Management. Following to offered instructions will make work of the amateur mechanic of more effective, will allow to organize in the best way and qualitatively to execute various technical procedures and is pledge of half-number performance of all necessary works.

Fixture — the general information

Nuts, bolts, hairpins and the screws serving for connection among themselves of two or more details are called as fixture. At work with elements of fixture it is necessary to remember some things constantly. Practically in any carving fixture this or that type of kontryashchy and stopping adaptations is applied. It can be lock washers, lock-nuts, lock tags or special fixing hermetic for carving connections. All used fixture should be absolutely pure and direct, with an undisturbed carving and not rounded corners of six-sided turnkey heads. It is necessary to take for a rule without fail to make replacement of the damaged elements of fixture. Special самоконтрящиеся nuts with nylon or fiber inserts are not subject to a reuse, as at an otdavaniye lose the kontryashchy properties and at assembly always should be replaced.

The "become attached" fixture for the purpose of simplification of unscrewing and in order to avoid damages before an otdavaniye should be processed by special getting structure. Many mechanics prefer to use for this purpose turpentine which it is convenient to put from the special small canister with a long nouse. After fixture wetting by getting structure, it is necessary to give to means within several minutes properly to impregnate the oxidized contact layer. Strongly rusted fixture can be cut down by a chisel, is cut by a hacksaw or removed by means of special гайколома.

When cutting a head of a bolt or a hairpin oblamyvaniya on assembly the rest of a carving part can be drilled or taken by means of a special ex-tractor. The majority of repair trucks can undertake performance of this, no less than others (for example, restoration of the broken carving in carving openings), repair procedures.

Flat and lock washers at assembly should be established always into place in the original provisions. The damaged washers are subject to replacement without fail. Between a lock washer and a soft metal surface (for example, aluminum), thin sheet metal or plastic of a fixed detail always it is necessary to establish flat washers.

Sizes and classes of durability of fixture

For many reasons manufacturers of cars all wider and more widely apply metric fixture. However, it is important to know a difference between this (more universal) fixture and fixture of the SAE standard used sometimes (or American). Despite external similarity, elements of these two types of fixture are not interchangeable.

All bolts as the SAE standard, and metric, are classified on diameter, a step of a carving and length. For example, the bolt  of the SAE 1/2-13 x 1 standard has an inch half in diameter, 13 rounds of a carving on one inch and length of 1 inch.

Sizes/marking of a class of durability standard (SAE and USS) bolts

Metric bolt М12 — 1.75 x 25 has diameter of 12 mm, a carving step (distance between the next rounds) 1.75 mm and length of 25 mm.

Sizes/marking of a class of durability of metric bolts

Both bolts are outwardly almost identical, however are not interchangeable.

In addition to the listed signs, both metric bolts, and bolts of the SAE standard can be identified visually by a way of survey of a head. For a start, the distance between лысками шлицов heads of a metric bolt is measured in millimeters, whereas at American - in inches (the same is fair and for nuts). As a result, the wrench of the SAE standard is not necessary for use with metric fixture, and on the contrary. Besides, on heads of the most part of bolts of the SAE standard usually there are the radial notches defining the maximum admissible effort of a tightening (durability degree) bolt. The more the quantity of notches, the is higher admissible effort (on cars bolts of a class of durability from 0 to 5 are usually applied). The class of durability of metric bolts is defined by a digital code. Figures of a code are usually cast also on a bolt head (on cars bolts of classes of durability 8.8, 9.8, and 10.9 are usually applied).

Marking of a class of durability of bolts

Also, on labels of a class of durability, it is possible to distinguish class SAE nuts from the metric. Dot labels are applied to identification of a class of durability of standard nuts, proshtampovyvayemy on one of face surfaces while marking of metric nuts is made by means of, besides, digital code. The more the quantity points/value of a digital code, the is higher admissible effort of a tightening of a nut.

Marking of a class of durability of standard six-sided nuts

Marking of a class of durability of metric six-sided nuts

End faces of metric hairpins also are marked according to a class of their durability. The digital code whereas on smaller have marking in the form of geometrical figures is put on large hairpins.

Marking of a class of durability of metric hairpins

It is necessary to notice that the considerable part of fixture, in particular a durability class from 0 to 2, is not marked at all. In this case the only way of difference of the American fixture from metric is measurement of a step of a carving, or a sravnivaniye of rounds with rounds of unequivocally identified element.

It is necessary to remember that under classification of SAE only small fixture gets. Larger elements with not metric carving is fixture of the American standard (USS).

As the fixture of the same geometrical size (both standard, and metric) can have various classes of durability, at replacement of bolts, nuts and hairpins it is necessary to give particular attention to compliance of a class of durability established new elements removed on a durability class.

Technique and order of a tightening of carving connections

The tightening of the most part of carving connections should be made with the efforts defined by requirements of Specifications, given in the beginning of each Chapter of the real Management (it is necessary to understand a torque enclosed to it as effort of a tightening of fixture). The tightening with excessive effort can lead to violation of integrity of fixture whereas the nedotyagivaniye conducts it to unreliability of a joint of interfaced components. Bolts, screws and hairpins, depending on a material of which they are made, and diameter of a carving part, usually have strictly certain admissible efforts of a tightening, many of which as it was already mentioned above, are provided in Specifications at the beginning of each Chapter. Strictly adhere to the provided recommendations about efforts of a tightening of fixture applied on the car. For a tightening of the fixture which has not been mentioned in Specifications, it is necessary to use the card of admissible torques given below. The values given in the table are focused on fixture of classes of durability 2 and 3 (more high-class fixture allows a tightening with big effort), besides, it is meant that the tightening dry (with an ungreased carving) the fixture screwed in steel or cast (not aluminum) a detail is made.

Metric carvings

Trumpet carvings

Carvings of American
standard

Located on perimeter of any component the fixture (such as bolts of a head of cylinders, the pallet of a case and various covers) in order to avoid deformation of a detail should be given and be tightened in strictly certain order. The order of a tightening and an otdavaniye of such fixture is given in the text of the corresponding Heads of the Management, and also on сопр. illustrations. If the special order is not stipulated, in order to avoid component deformation, it is necessary to adhere given below instructions.

At the first stage all bolts/nuts should be tightened by hand. Further, each of fixture elements in turn reaches on one complete revolution, and transition from one bolt/nut to another should be carried out in a diagonal order (cross-wise). Further, having returned to the first element, it is necessary to repeat procedure in the same order, tightening fixture for a half of turn. Continue procedure performance, holding out each element already on a turn quarter for one approach until all of them will not appear tightened with demanded effort. At an otdavaniye of fixture it is necessary to operate in a similar manner, but upside-down.

Dismantling of components

Dismantling of all components should be carried out in such manner that at installation each detail could be established on the former place and the correct image. Try to remember characteristic external features of knot assembled, in case of need, make landing marking of the details which installation can be into place executed ambiguously (for example, the persistent washer equipped with a flute on a shaft, etc.). Placement of the removed details on a pure working surface in that order in what their removal was made will be good idea. Useful there will be also a drawing up of the elementary schematic sketches or step-by-step photography of an assorted component.

At an otdavaniye of fixture try to make marking of its initial situation on assembly. Often, installation of fixture and washers on a former place right after removal of the corresponding detail allows to avoid confusion at assembly. In the absence of such possibility, all fixture should be put in specially prepared for this purpose broken into sections and as appropriate marked box, or it is simple on the separate marked boxes. Such approach appears especially useful at work with the components consisting of a set of fine details, such as the carburetor, the generator, the klapanny mechanism, the dashboard or elements of a decorative upholstery of salon.

At a detachment of electric contacts and sockets it is necessary to pay attention to marking of wires or plaits by means of an adhesive tape with the put on it digital or alphabetic code.

Prokladochnye of a surface

On all cars sealing laying is applied to sealing of a place of a joint of interfaced surfaces of two or more details and serves for prevention of leakages of oils and other working liquids and maintenance in assembly of the increased pressure/depression.

Often such laying before installation becomes covered by a liquid or pastelike sealing compound (hermetic). Sometimes, eventually, or under the influence of the increased temperatures or pressure there is so strong "prikipaniye" of interfaced surfaces to each other that the partition of details becomes an exigeant task. With many cases successful separation of the "become attached" components is helped by an obstukivaniye them outside on joint perimeter a hammer with soft the brisk. It is possible to use for this purpose as well a usual hammer, striking blows through a wooden or plastic pro-rate. It is not necessary to make an obstukivaniye of cast cases and components sensitive to concussion. At emergence of such difficulties always first of all check, whether all fixture is removed.

Avoid a podrychazhivaniye of details by means of a screw-driver or the mount, entered into joint area as thus interfaced surfaces can be easily damaged that further will lead to development of leaks. If to avoid a podrychazhivaniye of the "become attached" elements of assembly it is not possible, use for this purpose the handle from an old smetka, but remember that all formed chips should be carefully removed both from interfaced surfaces, and from internal cavities of components of the dismembered knot.

After division of details their interfaced surfaces should be smoothed carefully out with scraper application for removal of traces of a material of old laying. The hardened fragments can be softened previously by means of the converter of a rust or a special chemical composition. As a scraper the piece of a copper tube with the flattened-out and pointed end in this case can be used. The remains of some laying easily can be removed by means of a copper brush, however, regardless of the applied method, interfaced surfaces as a result of processing should become absolutely pure and dry. If for any reason the interfaced surface appeared is damaged, before assembly of knot fill defects with prokladochny hermetic. In most cases it is necessary to use not stiffening (or not up to the end stiffening) hermetic.

Councils on removal of hoses

Measures of precautions which should be observed at removal of hoses, are very close to the measures shown at dismantle of laying. Avoid damage of surfaces of unions and branch pipes on which the ends of hoses as it can be at the bottom of development of leak