Or when dismantling the gearbox, many drivers have to unscrew and tighten hub nut wheels. But this is not as simple as it seems from the outside, and the nut must be tightened to a certain torque, otherwise there is a risk of the bearing turning on the hub and subsequent . In addition, most of the keys sold in stores are not designed for the high tightening torque that the hub nut requires. In this short article we will look at the importance of this seemingly simple operation, and how to do without torque wrench.

In the 80s of the last century, they finally abandoned conical roller bearings, and even on our domestic cars(front-wheel drive) began to install ball (or roller) double-row bearings (or single-row with a thrust shoulder). And finally, there is no need for precise adjustment of tapered bearings, in which for many, adjusting the required clearance was not an easy task.

Indeed, in modern non-tapered bearings, the axial clearance is set by the bearing manufacturer (read about bearings and their markings) and no adjustments are required when assembling the unit. But here's the importance correct tightening Many people do not attach such bearings, or rather hub nuts, but in vain.

1 - halves of the inner race of the bearing, 2 - outer race of the bearing, 3 - balls, 4 - bearing cage, 5 - CV joint tip (trunnion), 6 - washer, 7 - nut.

For example, let’s take the common one in our front wheel drive cars(VAZ 2108) hub unit, with double row ball bearing(its marking is 6-256907E2S17), shown in the figure on the left. If you tighten the hub nut 7 on the thread of the end of the CV joint, then the halves of the inner race of the bearing will close completely and further convergence of the ball raceways will no longer be possible. And in this clamped state, the axial clearance in the bearing will be approximately 0.06 - 0.08 mm.

This means that hub nut 7 must hold the halves of the inner race of the bearing long enough (and provide the required clearance of 0.06 - 0.08 mm), that is, throughout the entire service life of the bearing. This means that the nut should not allow the distance between the halves of the cage to increase and the required clearance to be violated. And what better moment tightening this nut as prescribed by the factory, the longer the required clearance in the bearing will be ensured.

Hub nut - required tightening torques .

The required tightening torque for the hub nut is prescribed not by the bearing manufacturer, but by the vehicle manufacturer, and this torque is different cars is slightly different (for example, in the VAZ 2108 the torque is 225.6 - 247 N m, that is, 23 - 25 kgf m). Therefore, it is advisable to clarify it in the factory recommendation of your car.

It is interesting that recommendations for the tightening torque of the same bearing may differ slightly from different car factories. This most likely depends on the different strength of the metal of the hubs, axles, nuts or threads on the shank of the CV joint. And only the manufacturer of the machine knows this strength of the metal from which everything is made.

For example, as I already said, the tightening torque of the wheel bearing on a VAZ2108 car, its factory recommends 23 - 25 kgf m, and for the same bearing the AZLK plant (for Moskvich) prescribes only 14 - 16 kgf m, and the Moskvich plant does not allow in any way case exceed this value.

And such a bearing can be tightened even stronger, because this is what they do on VAZs, and even the smaller bearing for the Oka car (marking 6-256706У1С17) is even tightened stronger, with a torque of 19 - 23 kgf m. Most likely, the material of the Moskvich hub , or the threads of the CV joint shank on Moskvich are weaker than on VAZ cars. Although the same M20x1.5 thread is cut into wheel studs and the nuts of a ZIL truck, and they are tightened to a torque of as much as 60 kgf m, and nothing.

Well, for “Tavria” (1102), its plant chose the “middle” and the tightening torque of the same bearing (as on the eight and forty-first Moskvich) is 15 - 20 kgf m.

One more thing to consider important point: when operating a car, the torque of the nut tightened at the factory can gradually loosen, and when the bearing life still allows you to drive and drive. The tightening torque gradually weakens due to changes in the structure of the metal, and if the tightening weakens, then the clearance in the bearing becomes larger. And even a slight increase in this gap of 0.06 - 0.08 mm (between the balls and their tracks) quite significantly reduces the bearing life, especially when traveling on our bad roads.

This means that it is useful to tighten the hub nuts after about 20,000 km (or check their tightness), just as they tighten the bolts after a certain mileage. In this case, it is useful to unscrew the hub nut one turn and tighten it again. Then we jack up the car and rotate the wheel forward and backward several times, and then lower the car onto the asphalt and tighten the nut to the required torque.

As I already said at the beginning of the article, most torque wrenches on sale are not designed for a torque of 25 kgf m, and some car owners do not have any torque wrench at all. And the ratchet cranks of most tool sets are also not designed for such a moment. Their ratchet can break at any time from such force (if you lengthen the lever using a pipe), and you can injure yourself. Of course, there is a high-quality ratchet tool designed for such force, but it is very expensive and not everyone has it. And of course they won’t “catch” the required moment.

There are two options for tightening the hub nut correctly and to the required torque, and they can be quite inexpensive. The first option is to weld a powerful lever to the socket head, and I will write about the required length of this lever a little lower.

By the way, on sale you can find, instead of a head, a powerful tubular (socket) wrench, and the thickness of the pipe wall of such a wrench is quite decent. This wrench has holes for a powerful wrench or pry bar. But you can, using the adapter shown in the figure on the left, attach a pipe of any length to such a wrench.

The second option is to look for a ready-made truck key on sale, and such a key (for example 30-32 or 27-30) can easily withstand a tightening torque of up to 30 kgf m. It can be purchased in specialized stores for Kamaz, GAZ, Ural, ZIL trucks , or imported heavy vehicles.

The length of the lever can be lengthened using a pipe, but sometimes it is enough to step on the lever with all your weight. Moreover, the required tightening torque is easy to calculate. If the length of your key or a lever welded to the socket head is 40 centimeters, and the weight of a person who weighs 70 kilograms presses on it, then the tightening torque will be 28 kgf m. But usually drivers put a meter-long pipe on the key and press with the entire weight (sometimes in 90 - 100 kg), this is approximately twice as much as necessary.

Once the nuts are tightened, there is no need to lock them with a washer (or cotter pin), as was previously the case on older machines with tapered bearings, since the nuts have locking bands. Or there are self-locking crimp nuts, or their soft bands, which are pressed into the groove of the axle.

I hope this article will help new drivers to properly tighten the hub nut (or hubs) and significantly extend the life of your wheel hub bearing, good luck to everyone.

Having correctly identified with how hard to tighten hub nut and by stopping in time, you can avoid thread failure and the need to perform expensive repairs, given today's prices for nuts. Craftsmen perform this work using a special torque wrench. Since the wheel bearing is a rather capricious product and is not always at hand optional equipment, then knowing the answer to this question is very important. Before work, it doesn’t hurt to determine what type of it is installed, for example, it can be conical or roller.

Features of tightening the hub nut

Neither understanding with how hard to tighten wheel nuts It's better not to take this job. If you overtighten them, then a breakdown will occur, and if you don’t tighten them, then scrolling may occur, seat under the bearing will deteriorate. Anyone who is not confident in their knowledge can use a spring cantor, but you can get by with more in a simple way. Ratchet drivers most often cannot provide sufficient force, and the tools designed for this are expensive.

To prevent damage and perform the job correctly, for broaching It is recommended to use a lever that is a meter or a little longer. If a fine thread pitch on a car hub may require a force of 20 Nm, plus it will be necessary to turn the key another 90°, in total such efforts will give a very decent tightening torque. Anyone who remembers physics can make a simple calculation. To do this, you need to know your weight and the length of the lever. A value of 20 Nm is equal to a force of two kilograms with a lever length of a meter.

Effort then At what torque should I tighten the hub nut?, depends on individual characteristics vehicle. Torque recommendations for even the same bearing often vary. They depend on the quality of the metal of the hubs, the strength of the nuts, axles, and threads. Usually 19-23 kgf/m is enough. If the bearing weakens and the gap reaches 0.06-0.08 millimeters, this will significantly affect the reduction in the service life of the entire mechanism.

Experts who have worked in car repair shops for many years recommend tightening the hub nuts every 15-20 thousand kilometers. In this case, it will be useful to loosen them a little by one or two turns. It is best to have the car raised with a jack. To implement this process Many people advise using a tubular spanner, because it has thick walls and there is room for a wrench, and it is more powerful. Thanks to a special adapter, you can use a pipe.

Modern cars are equipped with crimp nuts that do not need to be locked. They have belts and they will press themselves into the grooves of the axle. You don’t need to put all your hundred kilogram weight on the key; it’s actually twice as hard as necessary. Knowing for sure what is the tightening torque for the hub nut? you can avoid losing a wheel on the way, before this a knock will occur when turning, and the car may fly into a ditch.

First about the problem in general -

Sometimes, in order to unscrew a large nut without a suitable wrench, it is easier to use what you have at hand for this purpose than to run around the store looking for a wrench. I myself use this simple device that grabs and unscrews any pipes and large nuts. Moreover, all that is needed for it is a piece of profile pipe 30-40 centimeters long and a motorcycle chain. A bicycle bike for small sizes is also suitable. We weld the chain to the pipe with one end, and run the other end tightly around the nut and run it inside. We make a crease and the “clamp” is tightened, and the pipe acts as a lever. After an adjustable wrench and a gas wrench, this is the most important tool, and it’s cheap - there’s nowhere else to go.

Well, for a special case -

I can recommend the following.

The best universal tool for such interesting places is a plumber's wrench with a self-clamping movable jaw. He is good at getting to such places.

You can bend the jaws of a thin wrench (there are such in spare parts kits for motorcycles, bicycles and chainsaws) following the example shown in the photo below -

For a specific size of nut located in a hard-to-reach place, you can make such a “grip” from a metal plate 4-5 mm thick. on the handle and with a knob.

Mostly on the clamping nuts of mixers, the edges are 32.36 or 38 mm. Car enthusiasts may have a hub wrench of this size; it will also work well for this purpose. It looks like the picture below. In the same figure, I highlighted the key area, which can be taken as an idea homemade key- weld two pins onto a tube of suitable size that will rest against the corners of the nut faces, and make a knob from below.

In this article we will tell you how to unscrew a stuck nut, a rusty nut, a nut with torn edges or a completely round one. Cases with non-standard nuts – plastic and big size.

The material also describes the most suitable tool, incl. special tool, professionally used for working with fasteners.

The material is useful for those who intend to unscrew the fasteners of the engine crankshaft, hub, wheel, generator, exhaust manifold, variator and on other components and assemblies of a car, motorcycle or other equipment.

How to unscrew a nut

As a rule, nuts are unscrewed with hand tools - spanners or open-end wrenches, heads using a wrench or ratchet. However, it often happens problematic situations.

How to unscrew a nut when the nut cannot be unscrewed with a regular tool using the usual application of force? In this situation, you should choose from the available tool the one that fits better Total:

• thin short open-end wrenches, especially those with too loose (broken) jaws, are worst option, which is better to immediately abandon in a situation with unscrewing rusty stuck nuts (open-end wrenches will lead to torn edges and further difficulties);
• box wrenches with an extended handle are preferable to open-end wrenches, since they cover the perimeter of the nut more tightly;
• A 6-point socket wrench or socket is preferred over the 12-point versions;
• Due to its simplicity and strength, a crank is preferable to a ratchet, because for the latter, the application of increased forces can lead to damage to the mechanism (this is especially true for ratchets with a large number of teeth, each of which is smaller and not so durable);
• an air impact wrench will do a better job than a hand tool;
• in combination with a long wrench or air impact wrench the best solution there will be a Super Lock head, in which the force is applied not to the corners (edges), but to the planes, which eliminates the licking of the nut edges;
• A torque amplifier (multiplier) will help apply a force to a large stuck nut that is inaccessible using only the physical capabilities of a person.

Which way to unscrew the nut

In the vast majority of cases, fasteners have right direction threads: you need to unscrew the nut counterclockwise (look at the nut from the side of the free threaded end of the bolt or stud through which you need to drive the nut).

Accordingly, unscrew the nut with a left-hand thread clockwise.

When deciding which way to unscrew the nut, just look carefully at the fasteners:

• on the side you can see the inclination of the threads at a small angle - unscrew the nut in the direction in which the thread “rises”;
• even if the threaded part is not visible, you can see the desired direction along the end of the nut at the point where the last turn of its internal thread exits.

How to unscrew a stuck nut

In order to unscrew a stuck nut, we recommend performing several preliminary preparatory operations:

• clean the fasteners from rust and dirt with a wire brush;
• tap the nut around with a hammer without damaging its edges and exposed threads.

When deciding how to unscrew a stuck nut, you need to take into account several possible ways, based on the actual condition and availability of fasteners for the tool, the composition and parameters of the existing tool, the feasibility of destroying the nut itself or the threaded part on which it is fixed.

The following options are available for unscrewing a stuck nut:

• apply heat to the nut (preferably until red and repeatedly);
• apply a penetrating compound (WD-40, liquid wrench or their analogues) into the contact gap between the nut and the thread of the bolt (stud), wait the time required for the product to work (from 20 minutes or more depending on the condition of the fastener and the activity of the product);
• increase the force impact on unscrewing by increasing the lever for applying forces through the use of an extended tool (or an extension attachment on a tool of normal length);
• apply special device– torque amplifier (another name is torque amplifier, torque multiplier);
• use a pipe wrench, holding the nut with it and applying force in the direction of unscrewing;
• clamp the nut in a rigidly fixed vice and unscrew it, rotating the entire part or assembly, if possible;
• clamp a small separate vice and try to unscrew the nut with it;
• use a pneumatic impact wrench;
• drill out the threaded rod on which the nut is stuck.

How to unscrew a broken nut

Damage to the edges (their breakdown) causes serious difficulties. Main solutions in in this case some:

• use a Super Lock head (acts on planes, not on edges);
• hold the torn nut in a pipe wrench (in a vice, clamp, pliers, etc.) and unscrew it;
• drive a nut of appropriate size onto the top of the nut with licked edges bigger size, the internal diameter of which allows it to be pressed into place, for additional fixation, drill a recess in the area of ​​contact of the nuts, inserting a metal rod (a piece of drill and a piece of nail) there as a key to prevent rotation) and unscrew the fasteners, using a tool the size of the nut of a larger diameter with working edges;
• put on a nut of larger diameter, weld both nuts together using a semi-automatic welding machine (covering the thread of the stud or bolt with a tube with a suitable wall thickness), unscrew the large nut together with the welded small one.

How to unscrew a round nut

For round nuts, when the edges are cut and smoothed completely by the previous ones unsuccessful attempts, or the nut was originally made in this form, you can also use several approaches:

• fit a standard hex nut of larger diameter into tension on it and drill a hole and a key that prevents rotation at the line of their contact and unscrew it using the large nut;
• if the side surface is sufficiently high, use a special tool - a pin driver;
• put a square washer of large thickness (comparable to the height of the nut), cut on one side and with the inner diameter of the washer exactly corresponding to the outer diameter of the round nut, onto the round nut, clamp the nut with a pipe wrench or a vice, giving in to compression, the nut in the cut will select a gap until it tightly covers the surface round nut, unscrew the fastener.

In the latter method, the probability of selecting a washer from a stock is low, so it is easier to make it yourself from a suitable piece of metal.

How to unscrew a nut while heating it

Heating the nut is often affordable, simple and effective way. When the metal is heated, the threaded surface of the nut expands, the corrosive bond is somewhat destroyed and the grip on the thread of the bolt or stud weakens.

For heating, you can use any suitable heat source: matches, wax candle, lighter, gas canister burner, blowtorch, gas cutter (carefully, at a sufficient distance so as not to melt the fasteners), etc.

If possible, it is better to heat the nut until red hot and unscrew it. If it doesn’t work the first time, then heating should be repeated several times. This may be especially true for nuts mounted on special remedy– thread locker.

How to unscrew a nut with soaking

Loosening of fastener sticking with soaking is further development relatively quick (20 minutes or a little more) application of special penetrating compounds.

The threaded part of the nut, as a rule, is not very tall, so if there is sufficient time for a long immersion in a penetrating or chemically active composition against rust, it is an effective solution.

There are two main approaches:

• generously moisten the rusty fastener in the thread area with an active agent, wrap the accessible threaded shank of a bolt or stud in the nut area with a rag soaked in this agent or place it on top of the end (if the shank does not protrude beyond the plane of the nut), cover it with cellophane or rubber and wrap it;
• Immerse the fastener completely in the chemical.

Care should be taken to ensure that penetration active composition happened strictly vertically from top to bottom.

The following chemicals can be used:

• penetrating compounds, in addition to the previously mentioned WD-40 and the “ Liquid key", kerosene, gasoline, carburetor cleaner, lock defroster and others can be used;
• rust converter;
• compounds that are chemically active against rust - table vinegar, iodine, alcohol, Coca-Cola, etc.

How to unscrew a large nut

For large nuts, 6 main methods can be effective:

• use a special tool that is designed for repair and maintenance of agricultural machinery, tractor and special equipment– torque amplifier (other names – torque amplifier, torque multiplier);
• use a wrench with a long handle or a socket with a long wrench corresponding to the size of the nut (if necessary, use a special extension or put on a pipe suitable size on the rotating outer end;
• in the absence of a suitable size key or head, cut a notch in a strong metal strip from one edge strictly according to the distance of the parallel edges of the nut, thereby creating an individual key for a large nut;
• use a chisel and hammer to strike the edge of the nut in the direction of unscrewing;
• Electrically weld a metal rod (optionally a corner, channel or other profile) to a large nut as a T-shaped or L-shaped handle, which you can use to unscrew it;
• if the threaded end of the bolt or stud does not protrude beyond the outer surface of the nut, then you can drill 2 recesses in the large nut from this side, then drill 2 holes at the same distance in a strip of thick metal (angle or other profile), align the holes and insert into them metal rods, apply force to unscrew (the rods will act as shear keys, transmitting torque to the nut).

The last 2 methods can be combined: weld a metal profile with a flat surface to the outer upper plane of a large nut, additionally drill a couple of holes and insert dense metal rods that will work as shear keys when force is applied. This will significantly strengthen the welded joint.

When deciding how to unscrew a large nut, you must proceed from the need to maintain the integrity of the nut.

How to unscrew a plastic nut

Plastic nuts, as a rule, differ in the shape and size of their working surfaces from ordinary metal nuts. The flexibility of the material limits, although does not always exclude, the use of a tool that compresses on both sides (pipe wrench, vice, etc.) - it is necessary to cover as much of the perimeter as possible.

You can unscrew the plastic nut:

• a special factory-made wrench, the working surface of which follows the profile of the perimeter of the nut;
• a self-made key;
• oil extractor car filters, which firmly encircle the circumference with a steel tape or several metal legs (the stronger the applied force, the stronger the coverage);
• press wooden blocks and two opposite sides and both of them simultaneously hit with hammers in the direction of unscrewing;
• for a small diameter - with pliers with a wide opening;
• pipe (gas) wrench.

If standard key lost, then it’s easy to make a key with your own hands from not the most difficult metal (steel or aluminum) or dense plastic. First, it is wiser to make a template from cardboard, check the tightness of the fit on the plastic nut, then transfer the outline to a suitable piece of sheet material and cut it out taking into account the handle.

How to unscrew a nut in a hard-to-reach place

To work with hard-to-reach fasteners, use a special tool:

• wrench or ratchet with a short handle;
• ratchet with a large number of teeth in the mechanism (gives a small angle of rotation, which is important in cramped conditions);
• extensions to heads;
• flexible drives for heads.

When deciding how to unscrew a nut in a hard-to-reach place, you must first find a suitable tool - purchase it or ask for a loan.

How to unscrew a nut with its destruction or damage

In the most hopeless cases, when everything available methods and the tools did not produce results, the fastening remains to be separated by destroying the fastener:

• placing the chisel against the edges of the nut, hit it with a hammer in the direction of unscrewing;
• cut off the fasteners using a power tool with a cutting wheel;
• cut with a hand hacksaw;
• destroy the nut by drilling numerous holes;
• cut the nut with a chisel and hammer (easier after pre-drilling the holes);
• use a tool specially created for this purpose - a nut;
• put on a larger nut, weld both nuts together around the perimeter using a semi-automatic welding machine (covering the threaded part of the bolt or stud with a tube with sufficient wall thickness to prevent welding into one), unscrew the large nut with a wrench.

Conclusion

When deciding how to unscrew a nut, it is very wise to immediately use a suitable effective tool and carry out preliminary preparation taking into account the condition of the fasteners. Unprepared use of brute force with an unsuitable tool can most likely lead to damage to the edges of the nut, breakage of the stud or tool.

Before unscrewing the nut, it is worth cleaning the threaded part of the stud or bolt, applying a penetrating compound and only then applying force. Using the techniques described in this article, even the most difficult cases can have a positive outcome if you spend some extra time on preparation.

Returning to this article when needed, you can find the necessary hint in the answer to the question of how to unscrew the nut of the engine crankshaft, hub, wheel, generator, exhaust manifold, variator and other components and assemblies.