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 be impossible. 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 naturally, 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.

After replacing the wheel bearing, an important moment comes - tightening. It is necessary to clamp not with “bare” hands, but using a special device - a torque wrench. Since the service life of the equipment and the quality of control of the technical equipment directly depend on the completeness of the tightening.

Each vehicle has its own wheel bearing tightening torque. It is clearly described in the instruction manual. If for some reason the manual is lost, you need to use the Internet or contact the nearest auto repair shop for clarification.

Wheel bearing tightening

The wheel bearing tightening torque is the actual force with which the hub nut is clamped. Force is measured in N/m or kg/m, depending on the magnitude and conversion task.

Each bearing in its design has a slight axial clearance. It is necessary for the correct operation of the mechanism, namely:

• to prevent sideways movement;
• reducing the actual friction force;
• uniform distribution of thermal expansion;
• voltage distribution;
• increasing the contact area.

How to properly tighten a wheel bearing

The tightening value of the front and rear bearing is calculated based on a number of factors, such as:

1. Minimum and maximum permissible size(parameter) of the bearing.
2. The amount of axial clearance.
3. Type of thread pitch (large or small).

The above list of data is of a template nature and in each specific situation may be supplemented by new factors. However, the above reasons remain the same, regardless of the situation.

Wheel bearing torque

• VAZ, NIVA: from 19.6 to 24.6;
• brand Ford models Focus, Fusion, Mondeo, Transit: from 45 to 53;
• all Chevrolet models: 18.9 – 19.5 or 25.0 – 30.1;
• Renault models Duster, Megan, Sandero, Logan: 175 and 280;
• Opel various models: 150.

To carry out preventive and repair work It is common to use a torque wrench. This practice exists in service stations. A device with a scale is built into the design of the key. Knowing the required indicator, you can easily tighten the nut. The main thing is not to overdo it, as you can break the thread on the fastener.

Depending on the modification of the key, various limiters are installed:

• unregulated;
• with adjustment;
• with tightening indicator;
• with installed digital display.

Depending on the type of torque wrench selected, adjustments are made wheel bearings.

Owners often ask the question: is it possible to tighten wheel bearings without actually having a torque wrench. It cannot be prohibited, but it is not recommended either. Because you can't calculate the effort. The consequences of such tightening are obvious: backlash and premature failure.

Now you know how to adjust the wheel bearing yourself. Despite the simplicity of the actions and the design of the mechanism, it is recommended to service your technical equipment in specialized auto repair shops in order to avoid negative consequences and damage to adjacent parts.

Before carrying out preventive measures, do not forget to purchase only high-quality and original components recommended or approved by the manufacturer. This will increase the service life technical means and reduce the number of breakdowns to a minimum.

Repairing your own front wheel drive car, for example, when changing a CV joint, a wheel bearing, or dismantling a gearbox, many drivers have to unscrew and tighten the wheel hub nut. But this is not as easy as one might think from the outside, and the nut must be tightened to a certain torque, otherwise there is a likely risk of the bearing turning on the hub and its subsequent repair. In addition, most of the torque wrenches sold in stores are not calculated for the enormous 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 a torque wrench.

In the 80s of the last century, tapered roller bearings were finally abandoned, as well as domestic 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 longer a need correct adjustment tapered bearings, in which for many, adjusting the required clearance was not an easy task.

Since in modern non-tapered bearings, the axial clearance is set by the bearing manufacturer (we read about their markings and bearings here) and no adjustments need to be made when assembling the unit.

But the importance of correct tightening of such bearings, and nuts are more correct hubs, many do not attach, but in vain.

VAZ 2108 hub assembly with double-row bearing
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 one common in domestic front wheel drive cars(VAZ 2108) hub unit, with a 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 the upcoming convergence of the ball raceways will be impossible. 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 for a sufficiently long time (and supply required clearance 0.06 - 0.08 mm), in other words, throughout the entire life of the bearing.

And that means the nut should not allow the distance between the halves of the violation and the required gap to increase. And the more accurate the tightening torque of a given nut, 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 not prescribed by the bearing manufacturer, but by the factory and the vehicle manufacturer. various machines differs little (for example, in the VAZ 2108 the torque is 225.6 - 247 N m, in other words 23 - 25 kgf m).

Based on this, it needs to be clarified in the factory advice of your own car.

It is noteworthy that advice on the tightening torque of the same bearing may differ slightly from different car factories. This probably depends on the different strength of the metal of the hubs, axles, nuts or threads on the shank.

And only the car manufacturer 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, but for the same bearing, the AZLK plant (for Moskvich) prescribes only 14 - 16 kgf m, and the Moskvich plant does not allow There's no way this value could be greater.

And such a bearing can be tightened even more tightly, since this is what they do on VAZs, as well as the smaller bearing for the Oka car (marking 6-256706У1С17) and even then it is tightened more tightly, with a torque of 19 - 23 kgf m. Surely the hubs and material , or the threads of the CV joint shank in Moskvich are not stronger than on VAZ cars.

Despite the fact that the same M20x1.5 thread is cut on the truck nuts and ZIL wheel studs, and they are tightened to a torque of as much as 60 kgf m, and nothing.

Well, for the “Tavria” (1102), its plant chose the “torque” and the tightening center so that the bearing (as on the eight and forty-first Moskvich) forms 15 - 20 kgf m.

It is important to take into account one more fundamental point: when operating a car, the torque of a nut tightened at the factory may slowly loosen, and at a time when the bearing life is still sufficient to drive and drive. The tightening torque slowly weakens due to the transformation of the metal structure, and suddenly the tightening weakens, then the gap in the bearing becomes larger.

And also a slight increase in this gap of 0.06 - 0.08 mm (between their tracks and balls) quite significantly reduces the bearing life, especially when traveling on bad domestic roads.

This means that it is useful to tighten the hub nuts after approximately 20,000 km (or control their tightening), just as they tighten the engine head bolts after a certain mileage. Along with this, it is useful to unscrew the hub nut one turn and tighten it again. After this, we jack up the car and rotate the wheel a couple of times forward and backward, and after that we lower the car onto the asphalt and tighten the nut with the required torque.

As I said at the beginning of the article, most of the torque wrenches on sale are not calculated for a torque of 25 kgf m, and some car owners, by and large, do not have any torque wrench. And the ratchet cranks of most tool kits are also not designed for this moment. Their ratchet can break at any second due to hardening (if the lever is extended by means of a pipe), and possibly be damaged. There is, of course, a high-quality ratchet tool designed for such hardening, but it is very expensive and not everyone has it.

And of course they won’t “catch” the required moment.

Correctly and to the required torque, there are two options for tightening the hub nut, and they can be done inexpensively. The first option is to weld a wonderful lever to the socket head, and I will write a little below about the required length of this lever.

By the way, it is possible to find on sale, instead of a head, a wonderful tubular (spanner) wrench, and the thickness of the pipe wall for the wrench is quite decent. This key has holes for a wonderful wrench or pry bar.

But it is possible, using the adapter shown in the figure on the left, to attach a pipe of any length to such a key.

The second option is to look for a ready-made key for trucks 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. You can buy it in special stores for Kamaz, GAZ, Ural trucks, ZIL, or imported heavy vehicles.

It is possible to lengthen the length of the lever using a pipe, but it is not uncommon to simply step on the lever with your entire weight. Moreover, the required tightening torque is easy to calculate. If the length of your key or the lever welded to the socket head is 40 centimeters, and the weight of a person weighing 70 kilograms presses on it, then the tightening torque will be 28 kgf m. But in most cases, drivers put a meter-long pipe on the key and press on everyone weighing (from time to time 90 - 100 kg), this is approximately twice as much as needed.

After tightening the nuts, there is no need to lock them with a washer (or cotter pin), as was previously the case on older cars with tapered bearings, since the nuts have locking bands.

Either there are self-locking crimp nuts, or their soft bands, which are pressed into the groove of the axle.

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

Unlike owners of cars of many foreign brands, owners of VAZ “classics” know how to adjust wheel hub bearings. Currently, the prevailing opinion among designers and automotive engineers is that non-adjustable and non-separable front wheel bearings are safer. We can only partially agree with this. New bearing changes along with the hub into which it is pressed at the factory.

Whether we like it or not, wear and tear is inevitable. After some time, play appears and there is only one way out - to buy an expensive bearing with a hub. Domestic auto industry stands on the side of our car enthusiasts.

It is much easier to replace only the bearings, which allow you to periodically adjust the hub play. Firstly, it is several times cheaper. Secondly, the operating life of the node increases. Thirdly, the adjustment can be made by the driver himself in a garage.

Why is it possible to adjust the wheel bearings on some cars?

Considering that the design of the classic VAZ series is borrowed from foreign cars, there are foreign cars in which the play of the front wheel bearings can be adjusted. This possibility is provided by the special design of the front wheel hub, which rotates on the axle shaft on two tapered (cone) bearings.

A distinctive feature of conical ones is that it is possible to establish play between the hub and the axle shaft by pressing the outer and inner races of the bearings against each other. In the hub, in the direction of the cones, the bearings are directed towards each other. If you tighten it gradually hub nut on the axle shaft, this will lead to stronger pressing of the rollers between the races. At some point the wheel will stop rotating altogether.

Thus, using just one nut, you can regulate the force with which the clips press the rollers. During operation, even heavy-duty metal alloys of bearings wear out, which leads to the appearance of excessive. This puts the life and health of both the driver and passengers and other participants at risk. traffic. All that needs to be done to fix this problem is to tighten and secure the hub nut. As soon as the nut, when tightened to maximum, no longer affects the amount of play, it is necessary to change the bearings.

Adjusting wheel bearings - step-by-step instructions

Before embarking on the regulatory process, certain preparatory steps must be taken. For such an important event, you really need a minimum of tools:

• jack;
• hammer;
• screwdriver;
• beard;
• wrenches for wheel bolts at “12”, “27”;
• torque wrench.

Whenever adjusting the bearing play, be sure to change the hub nuts. The nut is fixed on the axle shaft in the required position by riveting the collar of the nut into the groove on the axle shaft. If the collar is bent and bent again, then there is a high probability that the nut will return to its previous position.

With everything you need at hand, you can begin adjusting the wheel bearings.

Wheel bearing adjustment technology:

• the car is fixed on a level surface parking brake or other available means;
• lifts with a jack front wheel, after which it is removed along with the decorative caps;
• carefully, using a hammer, screwdriver or other spacer, press out the protective cap of the hub;
• the wheel is installed on the hub and tightened with at least two opposite bolts;
• the amount of play and the possibility of tightening are checked for what: with one hand you should hold the wheel at the top and make sharp rocking movements to the sides in the direction of the wheel axis, and with the other hand you need to press the washer located between the nut and the bearing race. If the axial clearance is more than 0.02 - 0.08 mm, adjustment should be taken;
• using a hammer and a pointed metal object (bit, core), it is necessary to unlock the bent sections of the hub nut collar;
• the nut is unscrewed and removed, a new one is screwed on instead (on the right trunnion there is a nut with a left-hand thread, on the left trunnion - with a right-hand thread);
• after tightening the nut with a force of 19.6 Nm, it is necessary to turn the hub several times in different directions so that the bearing rollers take their place;
• the nut is loosened and re-tightened, but with a force of 6.8 Nm. For reference: 10 Nm = 1.02 kg/cm 2 ;
• the nut is turned at an angle of approximately 25 degrees;
• the collar of the nut is jammed into the grooves on the axle shaft of the steering knuckle axle;
• The hub is assembled and the wheel is installed.

Adjusting the wheel hub bearings is a very important and responsible matter, because the safety of people depends on how correctly everything is done. In addition to strictly following all the rules, you need to know and take into account such aspects as:

• the degree of tightening of the hub nut;
• condition of bearing lubrication.

Some drivers mistakenly believe that tightening the nut tighter will extend the mileage. After the nut is fixed, the wheel must rotate absolutely freely and the established minimum technological play must be present. As it moves, all parts of the bearing heat up and expand. If you overdo it and tighten the nut too much, this can even lead to jamming or destruction of the bearing.

The bearings in the hub must be generously lubricated. During operation, the lubricant is subject to destructive effects: friction, overheating, and the appearance of abrasive metal impurities. If it's time to adjust the bearing play, you shouldn't save money on purchasing new lubricant. As a rule, Litol-24 is universal for wheel bearings. Lubrication is one of the important conditions for increasing bearing life.