Installing a self-locking differential for VAZ 2107: pros and cons

Why block him?

In certain situations this is necessary. To make it clearer, let's look at everything in order. If a car turns sharply or goes over rough terrain, its drive wheels travel different lengths. For example, when turning, the path of the outer wheel will be longer, and the path of the inner wheel will be shorter. Previously, when car speeds were low, this circumstance did not particularly worry anyone. But gradually the speed of the cars increased, and problems began to arise:

• tires wear unevenly;
• handling is seriously degraded.

All this happens due to the fact that the torque on the drive wheels of the car is always the same. Therefore, it became necessary to separate the drive wheels so that each of them had its own torque. This task is performed by the VAZ 2107 differential. If the road is smooth, there are no problems with this unit. But as soon as the car finds itself on rough terrain with the differential engaged, the wheels begin to slip, and driving the car becomes much more difficult. It is in this situation that the driver should lock the differential to increase the vehicle's maneuverability.

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When starting uphill, the benefits of locking appear only in conditions where there is snow or mud under the wheels.
If there are any differences in behavior on dry asphalt, they are negligible. When starting uphill, the benefits of locking appear only in conditions where there is snow or mud under the wheels. If there are any differences in behavior on dry asphalt, they are negligible.

On stable surfaces, the traction capabilities of the tires are almost equal to the traction capabilities of the 89-horsepower engine. As soon as you press the accelerator more aggressively, the Kalina enthusiastically begins to twist into the bend. I let off the gas and immediately straightened the trajectory. In general, it’s interesting and even fast, despite the somewhat unconventional techniques for driving a front-wheel drive car. That's just...

It's really easier to control it dry. True, as long as you go fast, but not extreme. As soon as sweeping slides appear, control becomes more complicated. After all, when drifting, the driver reflexively releases the gas, thereby provoking even greater drift of the front axle. You have to constantly feel for the optimal speed or, again, resort to rally techniques.

Types of blocking

There are three of them: manual (forced), automatic (self-locking differential) and partial.

The driver turns on the manual locking himself when he finds himself on rough terrain. It's simple: a switch is pressed in the cabin, after which a special limiting unit begins to operate, preventing torque from being distributed to the drive wheels depending on the path they travel. The advantages of such a lock are obvious: the driver himself decides when to engage the limiting mechanism, and the rest of the time this device does not work and, accordingly, does not wear out. There are also disadvantages: to lock the differential manually, the driver will have to take his mind off the controls. And he gets distracted in extremely difficult road conditions. The driver should also not forget to disable the lock when he is on a flat road. If you don't do this, you can break the differential itself. And finally, you will have to install not only the limiter itself, but also the system that will operate it, which is associated with certain technical difficulties.

An example of forced differential locking on VAZ and Niva cars

An example of a finished lock on a VAZ from Val-racing

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But this is still not a combat vehicle, but a family station wagon. Therefore, we will pay attention to less dynamic and exciting moments, but more in demand in everyday life. For example, does locking provide an advantage when starting up a hill? A twelve percent climb (packed snow under the wheels) was conquered by the car in both versions. At the same time, in a car with a free differential, I had to move off very carefully, measuring traction bit by bit. It is quite natural that the Kalina overcame a steeper, 16 percent slope only armed with a self-locking differential.

Which one to choose for VAZ 2107

The answer to this question directly depends on the operating conditions of the vehicle. If the car owner never goes into the city and moves exclusively on country roads and rough terrain, a full manual differential lock is suitable for him. If the driver drives around the city, but the quality of the roads there leaves much to be desired, it makes sense to opt for automatic disc locking. Finally, if a car owner drives on good city roads all year round, a partial differential lock mechanism is quite suitable for him. The best devices of this type are produced by Quaife, Lokka and Torsen. These are expensive components, the installation of which is best left to qualified specialists. At the same time, you can do simple blocking yourself. This is exactly what will be discussed below.

What is a differential and how the mechanism works

By its name, the differential denotes the difference, that is, it is a mechanism designed to distribute torque between the wheels of a car. The presence of a differential is mandatory for all cars. Rear-wheel drive sevens also have a differential, but what is it for and why it is necessary to install a lock, we will consider further.

Any car cannot constantly move in a straight direction, since it must turn around, maneuver and move in the required direction. When a turn is made, the wheels of the car move with different trajectories, that is, some travel a longer distance, while others travel a shorter distance. If the car did not have a differential, the car would not be able to turn around. When trying to turn, the following picture would be observed - one wheel would move along the surface, and the second would slip.

This is interesting! The main purpose of a differential (a mechanism that distributes torque) is to allow the wheels to rotate at different speeds.

The VAZ 2107 has a rear axle differential, which is presented in the form of a gearbox. The cardan drives the drive gear of the gearbox, which is connected to the gears of the axle shafts of the rear wheels.

Sequencing

1. Before starting work, 2 bushings are made from bronze or brass according to the drawing given below.

Locking brass bushing for VAZ 2107 gearbox

A pair of bushings in a spring from a valve of a VAZ 2110 car

Axle shaft removed from VAZ 2107

Standard gearbox removed from a VAZ 2107

A pair of bushings is inserted into the VAZ 2107 gearbox

Video: Installing a lock on seven with your own hands

To summarize, it should be said that differential locking on the VAZ 2107 was and remains a very controversial issue. On the one hand, the car's cross-country ability increases, it corners better, and acceleration becomes more dynamic. On the other hand, it is not so easy to keep an accelerated car on a straight line, and its tendency to skid increases. In a word, whether to install it or not is up to the driver to decide.

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If you want to improve the cross-country ability of a single-wheel drive car, then a self-locking differential (at least with a slight interference fit) is not the best solution.
The marginal improvement in all-terrain performance is not worth the investment. If you want to improve the cross-country ability of a single-wheel drive car, then a self-locking differential (at least with a slight interference fit) is not the best solution. The marginal improvement in all-terrain performance is not worth the investment.

Let’s supplement the subjective sensations with those experienced on light off-road conditions. The site was chosen to be ideal: as you move forward, the surface under the wheels gets worse. We passed a place where a car with a loose differential had recently gotten stuck. However, with the blocking, she moved only a little further. Toothy tires and especially snow chains would have given no less confidence.

Rear gear differential spool VAZ 2101, 2102, 2103, 2104, 2105, 2106, 2107

A hard differential lock of the spool type is used on VAZ 2101-2107 sports cars for participation in drifting and rally competitions.

Spool is the most reliable and simple solution for transmitting the same torque to both wheels of the rear axle of the car, which allows you to constantly keep the car in a controlled skid, as well as increase the stability and acceleration dynamics in a straight line.

Installing a spool differential allows you to avoid handicraft methods for solving the problem of completely blocking the differential, such as welding, which in turn is not reliable and is prone to breakdown.

Thanks to its relatively simple design, this type of differential is easy to install and does not require special maintenance.

The spool for VAZ 2101-2107 is produced in the factory using imported equipment, taking into account high manufacturing precision.

In warehouse in Samara

Operating principle of a self-locking differential

The traditional operation of the differential on the VAZ 2107 is based on a gearbox, which allows each of the wheels to work independently of each other. This is done to ensure that there is no slipping when performing any of the maneuvers.

Naturally, the lack of blocking in the VAZ Classic led to the fact that at the time of towing the vehicle’s cross-country ability is radically reduced. The differential lock on the VAZ allows you to eliminate this drawback. A reasonable question arises: is there any negative factor associated with installing a blocker? No, because it is controlled manually. It turns on only at the right moment. By the way, the UAZ (Bobik) uses just such a system to increase cross-country ability.

Only there it works simultaneously on several bridges. That is, forced blocking forces each of the bridges to rotate at the same speed. Although this creates additional stress on the engine, it really makes it possible to overcome any barrier.

But it should be noted that differential locking in the VAZ 2107 can be performed using several methods and gears. The most popular among them is the worm (also known as screw), but the disk also has its advantages. Its only drawback is the need for additional lubrication and the use of additives. Without them, the disc lock switches with a characteristic grinding noise and, as you might guess, wears out the gears.

But the worm system is considered the “golden mean”. Yes, it is less reliable; when switching, you feel a harsh pull, but it is inexpensive and is quite easy to install. It received this name due to the freely moving “worms” (screws), with the help of which the blocking is performed.

Features of use

• When the lock is turned off when turning, there is a strong jerk. This is due to a sharp reduction in the load on the transmission. When the differential lock is turned on, the wheels crash into the ground with a characteristic noise;
• the angle of rotation is greatly limited when the differential is locked 2107;
• you cannot lock the differential when driving on normal roads;
• When towing and checking the brakes on a stand, you also do not need to turn on the differential lock.

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How to set preload

Preload adjustment is carried out by installing a package of special spring washers that push the gears inside the lock. A complete package of such special washers, when folded together, is 1 cm thick, but all the washers are different in thickness so that you can adjust the differential preload moment.

To adjust the preload you will need:

• pointer torque wrench (a wrench with clicks is not suitable, it will take a long time to set up);
• a homemade special part made from a simple internal grenade (cut off and a bolt welded to it) - see the video below;
• set of spring washers (rings);

Procedure for adjusting preload:

1. Disassemble the locking differential (remember the sequence). After removing the cover, pull out the axle shaft auger gear; behind it comes a narrow gear with a large internal hole, but which has a side; then come those same adjusting spring washers. You can pull out the screw satellites (the preloads themselves) to check how much wear they have.
2. Install new washers.
3. Collect.
4. Using a torque wrench and a special homemade part, we determine the tightening torque. When the key begins to turn, at this moment the arrow shows the tension torque.

This video discusses the option of adjusting the locking washers of a VAZ 2108 car.

A preload of up to 5 kg does not flatten the washer to a flat state; such a tension moment is considered a resource tension. Locking with a tension of up to 5 kg will help not significantly lose its characteristics for about 4 years. Any blocking with tension in the first couple of months loses about 1 kg of tension.

Experts recommend making a preload of no more than 5 kg for a self-locking front differential, and no more than 7 kg for a rear differential. At a maximum differential preload of, for example, 9 kg, all spring washers will already be pressed and the effect of the springs will be lost.

Pros and cons of installing a self-locking gearbox

So, when installing a self-locking differential, you purchase:

• increased wheel traction on drive axles;
• increased cross-country ability off asphalt road surfaces;
• improved acceleration dynamics;
• improved cornering.

The price to pay for the installation is deterioration in handling (for a rear-wheel drive VAZ):

• it is difficult to hold the car when accelerating on a straight line;
• when turning, the “classic” has an increased tendency to skid;
• With any design, additional high-friction links appear, which increases, even slightly, wear and fuel consumption.