Technique for screw connections, bolts, nuts

In respect of new vehicles or engines virtually no problems with loosening the bolts, nuts, pins, etc. If the car has been in operation, it may be problems with the dismantling of threaded connections, especially those threaded connections that have long been subjected to aggressive environmental influences. The following guidelines can help you successfully overcome the difficulties.

When loosening the nuts from the studs, you must first clear the protruding above the nut of the screw stud with a wire brush in order to remove dirt and possible rust. This will eliminate the run of contaminated nuts thread. Before loosening the nuts to be treated purified plot thread rust. There are many similar solvents, so always follow the instructions in the attached instructions for use.

In the case of loosening bolts nuts welded body and it is desirable to treat these fittings rust on the inside of the body. The heads of these bolts and nuts welded themselves often come off.

Screw cap screws under ordinary or cruciform screwdriver can also otkruchivatsya difficult. Cruciform screwdriver often jump out of the slot, thus damaging it. In order to eliminate these phenomena, you can use the screwdriver under normal or cross-shaped with a through slot, communicating through the screwdriver handle, a metal rod, setting the slot of the screw head and tapped with a hammer on a screwdriver handle protrudes above its metal rod. In most cases, this method helps to loosen the threaded connection and the screws can be easily loosened.

In today's automotive industry are increasingly used threaded fasteners with special heads that somewhat resemble the shape cruciform slotted head, but nevertheless different from those. They are called Torx-head (see. Fig. 4). Tightening and dismantling of such fasteners is made by means of special nozzles, which can be purchased in the tool kit. With these nozzles can also be used to tap wrenches "rattles", extenders and other devices.

Bolts with head type hexagon or internal polyhedron can also bring difficulties in the process of loosening. As a first and necessary measures should be well clear Allen / polyhedron bolt head from dust and dirt (for example, using a small screwdriver) to insert a multi-faceted hexagonal key free access to the entire depth of the bolt head. If possible, use short inserts, which could knock a hammer to overcome the inertial resistance of the thread before unscrewing. In some cases, however, requires a special allen key. Sometimes, because of the short length of the key handle having difficulty loosening the bolts. We offer the following solution of such difficult situations, insert the key into the bolt head and put on his arm extender, for example any suitable socket wrench. Holding the key is fully seated in the bolt head, start to turn it over the inserted strip. This prevents rotation of the plug in the hex head bolts firmly seated due to slipping.

Small and well-head bolts available under hex plug can be unscrewed using a pipe wrench, one version of which is shown in Fig. 11, in those cases when the edges of the insert hex key tray. Follow precautions when working tong not to pinch your fingers.

Complications can also arise when loosening nuts and bolts with rounded edges due to the use of inappropriate size wrenches. Most often, such a situation occurs at the used cars. These nuts and bolts, you can try to turn away by a pipe (gas) key. Depending on the available space like nuts can be folded hack saw or chisel hacksaw, leaf blowing along the thread. In this regard, we recommend to use if space permits, a special device gaykoraskalyvayuschee (gaykoraskalyvatel). Its principle of operation is shown in Fig. 12: the rotation of the nut is clamped to the bolt until bursts, then it is removed in two halves. The advantage of this device lies in the fact that it does not damage the thread of the bolt.

The manual often mentioned self-locking nuts. From the very title of the nuts should be, that there is a device that makes it difficult for spontaneous unscrewing the nuts and is often destroyed by dismantling the connection. Therefore, all self-locking nuts should not be reused.

Sometimes it happens that the bolt head is cut off. To remove the remaining screw threaded portion of the threaded hole to drill a hole in the center of the remainder of the bolt, in which twists special screw extractor with left-hand thread. Levorezbovye screw extractors (fig. 13), which, like screws screwed into a prepared hole, sold in specialized stores car accessories. The tightening of the screw thread it begins to cut into the body fragment screws and drags him along, twisting of the threaded hole. Another possibility of extracting a fragment of the bolt - drill holes with a diameter close to the diameter of the threaded hole, which was tattered fragment of a bolt, and then tightening the threading tap in reamed body fragments.

Studs be turned out and twisted with two nuts zakontrennyh one another on the threaded portion.

Developed thread on aluminum parts often breaks down when tightening the bolts. In such cases, you should use special thread inserts. These inserts are twisted in the damaged threaded holes according to the installation instructions contained on their packaging, or damaged item with a threaded hole is delivered to the service station for cutting the new thread.

Fastener Tightening

On the threaded fasteners of all responsible units and components specified tightening torque. To ensure the specified tightening torques must use a torque wrench with interchangeable heads / nozzles, and sometimes with an extension cord. In many cases, it is impossible to get close to a particular bolt / nut to use a torque wrench or torque is so small that it can not be read off the torque wrench. In such cases the calculated torque when tightening (by a large experience) or controlled "by feel" the resistance of the thread. This applies primarily to the diameter of threaded connections 6 and 7 mm.