How to adjust the brake booster rod

Thank you all for your response!

yaris

I have self-feeding cylinders.

It's all about the gap between the GTZ and the VUT rod! I have not seen anyone write about adjusting it in any article!

I quote: Before installing the master brake cylinder, we control the protrusion of the head of its adjusting bolt relative to the mounting plane of the master brake cylinder flange, which should be 1.25-0.2 mm

. To adjust the protrusion of the bolt head, turn it with an 8-point wrench.

This was the reason for the brakes being applied almost to the floor! But the “instructions” don’t say a word that the rod itself needs to be held with pliers and the “head” itself must be turned. And the key is not "on" 8

"But still "at
7
". I removed the GTZ three times to adjust the rod. And then this rod needs to be “inserted” back! I will say this is not very easy, since the pipeline is already connected and laid! It’s good that I didn’t leave the original brake fluid reservoir with its rubber hoses. I feel like I suffered even more then! The pedal began to take where it should be - in the middle! But “the music didn’t play for long!” Still, I guessed wrong.

Thanks again to Deeptown

for the hint where to dig, for the consultation at the moment when I stopped near the Dorogozhychi metro station with an oak pedal and almost blocked brakes. I had one adjustable wrench with me, thanks to it I unscrewed the GTZ and relieved the pressure. Then, on the floor with live brakes, I drove to the garage. There, within 5 minutes I removed everything, tightened the rod 5 turns and calmly drove home. But I see that I can add a couple more turns.

The vacuum brake booster (VBR) is one of the main components of the vehicle braking system. Even the slightest breakdown can trigger a failure of the entire system and lead to serious consequences.

Brake booster

Almost all modern cars are equipped with vacuum brake boosters. They have a fairly simple design, but are very effective and quite reliable.

Purpose

The VUT serves to transmit and increase force from the pedal to the brake master cylinder (MBC). In other words, it simplifies the driver’s actions when braking. Without it, the driver would have to press the pedal with incredible force to force all the working cylinders of the system to function simultaneously.

Device

The VUT design consists of:

housing, which is a sealed metal container;
check valve;
plastic diaphragm with rubber cuff and return spring;
pusher;
follower valve with rod and piston.

A diaphragm with a cuff is placed in the device body and divides it into two compartments: atmospheric and vacuum. The latter is connected through a one-way (non-return) valve to a source of air vacuum using a rubber hose. In the VAZ 2106, such a source is the intake manifold pipe. It is there that, during operation of the power plant, a vacuum is created, which is transmitted through a hose to the VUT.

The atmospheric compartment, depending on the position of the follow-up valve, can be connected both to the vacuum compartment and to the environment. The valve is moved by a pusher, which is connected to the brake pedal.

The diaphragm is connected to a rod, which is provided to push the master cylinder piston. When it moves forward, the rod presses on the GTZ piston, causing the fluid to be compressed and pumped to the working brake cylinders.

The spring is designed to return the diaphragm to its initial position upon completion of braking.

How it works

The functioning of the “vacuum tank” is ensured by the pressure difference in its chambers. When the car engine is turned off, it is equal to atmospheric pressure. When the power plant is running, the pressure in the chambers is also the same, but there is already a vacuum created there by the movement of the engine pistons.

When the driver presses the pedal, his force is transmitted to the follower valve through the pusher. Having shifted, it closes the channel that connects the compartments of the device. The subsequent stroke of the valve equalizes the pressure in the atmospheric compartment, due to the fact that the atmospheric channel opens. The pressure difference between the compartments causes the diaphragm to bend, compressing the return spring. In this case, the rod of the device presses on the GTZ piston.

The force created by the “vacuum driver” can exceed the driver’s force by 3–5 times. Moreover, it is always directly proportional to the applied.

Location

VUT VAZ 2106 is installed in the engine compartment of the car on the left side of the engine shield. It is secured with four studs on the plate of the brake and clutch pedal bracket. The GTZ is fixed on the body of the “vacuum generator”.

How to troubleshoot

It makes sense to repair the vacuum brake booster system only in the event of partial failure of the booster pipeline, its check valve, or the valve seal. If replacing the listed elements does not produce results, then it is necessary to replace the entire VUT, since its design is non-separable and cannot be repaired.

Replacing a pipeline with mounting clamps makes sense for several reasons:

low price of materials;
difficulty in localizing the location of depressurization;
Difficulty in repairing cracks or other damage in the pipeline.

Replacing the pipeline itself is not difficult, and even a novice car enthusiast can easily handle it. The main thing is to buy a new set of pipes, clamps and appropriate gaskets from the auto store. Next, using plumbing tools, simply change one tube for another.

Repair of auxiliary pumps

As mentioned above, when a mechanical vacuum pump partially fails, some car enthusiasts simply remove their rod, thereby turning them off and eliminating the knocking noise that occurs when the pump operates. In this case, the brake booster will work, but not as effectively, which will result in a harder pedal. Some car enthusiasts get out of the situation by turning the rod 180 degrees. Sometimes this helps because it is only present on one part of them.

As for electric vacuum pumps, these units are usually irreparable; accordingly, they are simply replaced with new ones.

Source

How to check the vacuum booster

If the symptoms listed above occur, the vacuum unit must be checked. You can determine the functionality of the device without removing it from the car. For diagnostics, we need a rubber bulb from a hydrometer and a screwdriver (slotted or Phillips, depending on the type of clamps).

We carry out verification work in the following order:

Turn on the parking brake.
We sit in the cabin and press the brake pedal 5-6 times without starting the engine. On the last press, leave the pedal in the middle of its travel.
We take our foot off the pedal and start the power plant. When the “vacuum” is working, the pedal will move down a short distance.
If this does not happen, turn off the engine and move on to the engine compartment. We find the amplifier housing there, inspect the check valve flange and the end of the connecting hose. If they have visible breaks or cracks, we prepare to replace the damaged parts.

Video: checking VUT

Repair or replacement

Having discovered a faulty vacuum brake booster, you can go in two ways: replace it with a new one or try to repair it. It should be noted here that a new VUT without a master brake cylinder will cost approximately 2000–2500 rubles. If you don’t want to spend that much money and are determined to repair the unit yourself, purchase a repair kit for the old “vacuum unit.” It costs no more than 500 rubles and includes those parts that most often fail: cuff, shank cap, rubber gaskets, valve flanges, etc. Repairing an amplifier itself is not a very complicated process, but it is time-consuming. It involves removing the device from the car, disassembling, troubleshooting, replacing faulty elements, as well as adjustment.

Change the vacuum booster or repair it, the choice is yours. We will consider both processes, and start with replacement.

Replacing VUT with VAZ 2106

thin slotted screwdriver;
spanner set to “13”;
socket wrench set to "13".

Place the car on a flat surface and put it in gear.
In the interior, we bend the carpet under the pedal bracket. We find there the junction of the brake pedal and the booster pusher.
Using a slotted screwdriver, remove the spring retainer from the pedal mounting pin and the pusher shank.

After replacing the device, do not rush to install the master brake cylinder, since before this it is necessary to check and, if necessary, adjust the protrusion of the rod, which we will talk about after considering the VUT repair process.

Video: replacing VUT

Repair of the VAZ 2106 vacuum cleaner

vice;
slotted screwdriver;
small hammer;
pliers.

We fix the vacuum booster in a vice in any convenient way, but only so as not to damage it.
Using a slotted screwdriver and pliers, we flare the halves of the device body.

Caliper device

Let's move on. The front axle mechanisms are disk ones, consisting of calipers with the main brake elements - pads, and brake discs.

A caliper is a body with cylinders made in it for the pistons. This model has two of them, one for each block. The support structure is shown in the figure.

The caliper pistons have the form of a glass, which is placed in their cylinders, but they can move along it. To prevent fluid leakage, the pistons are equipped with o-rings.

Pads are small metal plates onto which linings made of friction material are glued.

The brake disc is made of metal for better adhesion to the surface of the pads; its side surfaces are well processed so that there are no protrusions or shells on them.

The VAZ 2107 brakes work like this: the fluid moves into the caliper cylinders, where it begins to push out the pistons. They come out of the cylinders, pressing the pads against the disc.

Bleeding the system

After carrying out any work related to the replacement or repair of brake system parts, the brakes should be bled. This will remove air from the line and equalize the pressure.

Tools and tools:

jack and wheel wrench;
key to "8";
rubber or silicone hose with a diameter of 6 mm;
a small, clean, dry container (preferably transparent);
brake fluid (to top up).

In addition to all this, you will definitely need an assistant to bleed the system.

Place the car on a horizontally flat surface. Loosen the nuts securing the front right wheel.
Raise the car body with a jack. Unscrew the nuts completely and remove the wheel.
Remove the cap from the fitting of the working brake cylinder.

Video: bleeding the brakes

At first glance, the process of replacing or repairing a vacuum brake booster may seem somewhat complicated. In fact, you just have to understand everything in detail, and you won’t need the services of specialists.

The effectiveness of your car's brakes is important - if the brake system does not work effectively, an accident may occur. To ensure precise brakes, a booster is installed on all modern cars; it ensures that the vehicle stops instantly when you press the pedal.

Repair of the vacuum brake booster is necessary if the brakes become “wobbly” and you have to press the pedal with great force to brake.

Symptoms of problems

The fluid brake system consists of many parts that can become unusable: pipes, wheel cylinders, calipers, drums and pads. Typical signs of a faulty master cylinder:

After pressing the pedal, the car stops slowly. The reason is that the cuffs of one or two pistons have lost their tightness - they have cracked or “floated”.
To slow down, you need to press the brake pedal hard. The phenomenon occurs due to swelling of the rubber of the piston seals.
The brake pedal travel is too short. The fluid inside the cylinder has nowhere to go because the compensation hole is clogged. Another option is that the passage is blocked by a swollen rubber seal.
A common symptom is pedal failure, the brakes coming on at the end of the stroke. This indicates complete wear of the cuffs; as a result, liquid penetrates behind the piston and rushes into the expansion tank - the cylinder “bypasses.”
The pads do not release the brake discs and drums and get very hot when driving. Options: one of the pistons is jammed or the bypass hole is clogged.

Repair of vacuum brake booster VAZ 2106, 2107, 2108, 2109, 2110

The vacuum brake booster (abbreviated as VUT) of VAZ vehicles makes the driver’s work easier - it enhances the effect of pressing the pedal in the braking system (TS). This unit consists of the following main parts:

valve;
metal case;
diaphragms;
piston;
rod;
powerful return spring;
a pusher that connects to the brake pedal;
protective cover;
flange for installing a check valve.

The body of the device is divided into two halves by a diaphragm, and the master brake cylinder is installed on the side where the vacuum is created. A vacuum (vacuum) is created by connecting this part of the housing to the intake manifold of the internal combustion engine, and when the engine is not running, the channel closes the check valve installed in the VUT flange. Air (vacuum) with the help of a rod and piston when pressing the brake enhances the braking effect, thereby making the driver’s work easier - there is no need to press the pedal with great force. After releasing the pedal, a powerful return spring allows the diaphragm inside the housing to return to its original position. When the engine is turned off, no vacuum is created in the system and the vacuum brake booster does not operate.

On VAZ-2106-07 and VAZ-2108-10 cars, brake boosters are installed that differ in appearance, but the principle of operation of the devices is the same. We check the serviceability of the VUT as follows: press the brake pedal and start the engine - if the pedal “falls” (lowers under the pressure of the foot), the VUT works.

The main problem with a vacuum booster is damage to the diaphragm. When the diaphragm is ruptured, air penetrates from the outer part of the housing into the vacuum cavity, and a vacuum is not created in the device. But the malfunction may not necessarily lie in the device itself - often the VUT does not work due to air leaks or for other reasons:

the “vacuum” check valve is faulty;
there is air leakage from the hose connecting the intake manifold to the brake booster;
there is no compression in the internal combustion engine cylinder where the vacuum comes from.

It should be noted that the vacuum brake booster on VAZ 2106-10 vehicles is connected by a hose to the fourth cylinder of the engine.

Repair of the vacuum brake booster of VAZ 2106, 2107, 2108, 2109, 2110 should begin with the dismantling of this unit, then the VUT must be disassembled.

When you press the brake pedal you can hear a hissing VAZ 2114

Why do you hear a hissing sound when you press the brake pedal?

Most drivers react sensitively to various sounds that accompany the operation of car mechanisms. An exception is the case when a hissing sound is heard when you press the brake pedal. But it is not always worth panicking - especially in cases where the hissing of the brake pedal when pressed does not in any way affect the efficiency of the braking system. In order to understand the nature of this sound, let's take a closer look at the operation of the vacuum brake booster.

Vacuum booster circuit

The figure shows only a simplified circuit of the amplifier - the details of the device are, as they say, “omitted” - to make it easier to understand.

What happens when you press the brake pedal while the engine is running?

The brake pedal pusher simultaneously affects the booster rod and the so-called follower (in the diagram - “air” valve).

The follower valve opens, and air begins to flow into the amplifier cavity, separated by a diaphragm, from the pedal side. And since a vacuum has been created in the cavity on the side of the main brake cylinder (the check valve prevents air from entering it), the air entering through the air valve begins to put pressure on the diaphragm. The latter, rigidly connected to the rod, increases the pressure on the piston of the main brake cylinder created by the driver’s foot through the pusher. When the pedal travels when you press the brake, you can often hear a slight hiss emitted by the incoming air.

At the moment when the pedal travels, when you press the brake, you can often hear a hissing noise emitted by the air entering the amplifier housing. When the driver takes his foot off the brake pedal, the master cylinder piston and diaphragm rod return to their original position under the influence of the return springs (the vacuum booster return spring is not shown in the diagram). At the same time, since the follower valve opens only to release air (due to the fact that the driver stops pressing the pedal), it is squeezed out of the cavity by the same return spring - it also presses on the diaphragm.

While the driver does not press the pedal and the engine is running, a vacuum is maintained at all times on the side of the master brake cylinder in the amplifier cavity. The monitoring valve is closed, so the diaphragm is in a state of “equilibrium”, i.e. does not have any effect on the master cylinder rod.

Of course, this is only a general diagram of the operation of a vacuum brake booster, typical for all cars. On modern machines, it can be equipped with solenoids that increase the force on the master cylinder piston, and electric pumps can be used to extract vacuum. However, the operating principle of the amplifier remains the same.

Let's now consider how you can check whether everything is in order if, when you press the brake pedal, you hear a hissing sound from its side.

Vacuum booster diagnostics

If the brake booster does not work, it becomes noticeable - the brake pedal becomes hard.

But an indirect sign of a malfunction can also be a change in idle speed when the pedal is pressed. This is due to a lean fuel mixture caused by “excess” air entering the engine cylinders, which may even stall if the “suction” is too strong.

If the brake booster does not work, this becomes noticeable as the force required to press the pedal when braking increases.

Most often this is due to damage to the brake booster diaphragm. And it’s not necessarily due to old age - sometimes the sealing rings of the main brake cylinder leak brake fluid, and it gets into the booster housing.

Some car owners manage to rebuild the brake booster themselves - they even sell repair kits for domestic cars. But, in general, this is a thankless task - the body of the “vacuum generator” is non-separable, and not everyone can carefully and tightly connect its parts. In addition, the operation of the brake system is also affected by adjusting the protrusion of the “vacuum rod” from the housing - incorrect adjustment can reduce the efficiency of the booster or cause incomplete “release of the brakes” of the working brake cylinders.

Removing the vacuum booster 2106-07

Removing the VUT on a VAZ classic car is quite simple, and if you have minimal plumbing skills, this work is not difficult to complete. We remove the unit as follows:

we turn off the engine, disconnect the main brake cylinder (GTC) from the “vacuum chamber”, the cylinder is held on by two nuts. There is no need to disconnect the brake pipes and hoses from the turbocharger; we simply move the cylinder to the side;
we pull the hose off the check valve, while holding the valve so as not to pull it out and break it;
in the cabin, remove the fixing bracket on the brake pedal and release the VUT pusher;
then in the cabin we unscrew the four nuts that hold the “vacuum unit”, dismantle the unit - it is removed in the engine compartment.

Device

VAZ 2107 injector The VAZ 2107 injector consists of the following elements:

Computer;
Sensors;
Fuel pipes and hoses;
Fuel and air filter;
Actuators;
Gas tank;
Wiring.

The injector power system contains the main element - a computer or ECU. Its permanent memory contains a program (algorithm) in accordance with which the control of actuators is implemented, these include:

Fuel pump;
Injectors;
Idle air control;
Canister valve.

Each of the above elements performs its own function.

Gasoline pump

Turned on by the ECU output signal through a relay. Has a strainer and fuel level sensor. The gasoline from it passes through the fuel filter. The pump is located in the tank and to remove it, you need to remove the back seat, remove the hatch and unscrew the fastener.

Nozzle

It is a sprayer equipped with a solenoid valve. Triggered by an ECU impulse. Accordingly, the duration of valve opening (the amount of gasoline supplied) depends on the time the pulse is applied. It is installed on a ramp common to all injectors, a constant pressure in which is maintained by a valve. If it is exceeded, the valve opens and gasoline returns back to the tank. The injector enters the intake manifold. The air flow, passing through the intake manifold, carries away a portion of gasoline ejected by the nozzle.

The structure of the VAZ 2107 fuel system

Idle speed control

The fuel system maintains engine idle speed using a regulator. It is a stepper motor connected to a conical shaped control body. Its approach reduces the air flow entering the intake manifold; its removal, on the contrary, increases it.

Canister valve

It is needed to turn on the ventilation of the adsorber, which accumulates gasoline vapors and releases them into the intake manifold at the right moment.

The following sensors are installed on the VAZ 2107:

Crankshaft position;
Mass air flow;
Throttle position;
Coolant temperature;
Speed;
Oxygen content in exhaust gases.

Crankshaft position

This parameter is needed by the ECU to open the injectors in a timely manner. If this sensor malfunctions, the VAZ 2107 will not drive.

Air flow

Allows you to supply fuel in the right quantity. The signal from this sensor is sometimes incorrect. The reason for this may be its malfunction caused by high humidity or low temperature. An air filter with condensation inside or dirty will adversely affect this sensor.

Coolant temperature

The parameter is needed so that the ECU understands whether the engine is warmed up. This is necessary for the correct operation of a cold motor. The mixture is enriched due to temperature correction.

Oxygen concentration

The oxygen content in the exhaust gases must be measured to adjust the composition of the fuel mixture. It doesn't work when it warms up. This is advisable because the mixture is enriched.

Disassembling vacuum booster 2109

It is not difficult to disassemble VUT 2108-2109, but for disassembly it is necessary to fix the device. We disassemble the node in the following order:

clamp the “vacuum sealer” in a vice;
using a screwdriver on the body, we bend the grooves with which the two halves are held together;
when almost all the rivets are straightened, it is necessary to hold the outer part of the body - a spring is installed inside the device, and it can shoot. If the old diaphragm is put back into place, there is no need to push the screwdriver far inward, as the rubber seal may be damaged;
remove the rubber covers from the fastenings (2 pcs.);
dismantle the plastic casing together with the diaphragm and pusher assembly;

Typically, the repair kit for the VAZ-2109 vacuum amplifier contains a diaphragm, a cuff, a boot, covers (2 pcs.) and a valve. All parts should be changed so that you don’t have to redo the work later. When assembling a vacuum amplifier, it is better to immediately fix the diaphragm on a plastic casing, this will make it easier to mount the unit.

Repair of UAZ vacuum brake booster

Problems with the vacuum booster of UAZ vehicles can be identified by the following symptoms:

the engine suffers, and since on UAZ engines the vacuum hose goes to the manifold of the first cylinder, if the VUT is faulty, this particular cylinder is not completed;
a hissing is heard under the hood - the diaphragm is poisoning the air;
the brake pedal is hard and does not press when starting the engine;
There are wet leaks between the turbocharger and the amplifier (brake fluid is leaking).

If leaks of the brake fluid are detected in the area of the VUT, it is necessary to urgently change or repair the GTZ, but if the liquid has already entered the vacuum booster, most likely the VUT will also have to be repaired.

Another common malfunction in the brake system is failure of the check valve. This simple mechanism is very easy to check - you just need to blow into it. The valve should be blown freely in one direction (when rarefied air is supplied from the manifold), but air flows in the opposite direction with great difficulty. If the valve is faulty, it is blown freely in both directions.

Absolute vehicle malfunctions

During operation, the braking functions of the system deteriorate. This is due to wear and tear of components, assemblies and parts that require repair. Some vehicle malfunctions are included in a special “List...”, and driving with them is prohibited.

Inefficiency of the working vehicle

The most common malfunction of the brake system (including the VAZ-2107) is inefficiency, which is diagnosed by two main parameters (when carrying out a specialized instrumental study):

increasing braking distance;
increase in steady deceleration during braking.

Such faults can be determined by eye. After driving a passenger car on a dry road at a speed of 40 km/h, when braking, the car travels a distance exceeding 12.2 m. In this case, according to paragraph 2.3.1 of the traffic rules, the use of the vehicle is prohibited (even to the parking or repair site) . This malfunction may be due to:

presence of air in the system;
fluid leakage from the system;
worn out pads;
failure of the main or wheel cylinders.

In other words, almost the entire vehicle should be subject to monitoring. Repair (replacement) of components and assemblies will require bleeding the system to remove air from it.

Leakage of the working vehicle

During vehicle operation, components, assemblies and parts are subject to wear, which leads to depressurization of the system and leakage of brake fluid. This most often occurs in brake hoses or wheel cylinders. Fault repair is carried out by monitoring leaks and replacing damaged elements.

Leakage of the system also excludes the possibility of operating the car (according to paragraph 2.3.1 of the traffic rules).

Ineffective parking vehicle

This defect is the most common when the car moves involuntarily even with the handbrake locked. This is due to wear on the pads, discs or drums, as well as stretching of the cable elements.

According to the requirements of the “List...”, a parked vehicle must ensure that the passenger car is stationary:

on a slope of up to 16% at full load;
on a 23% slope when equipped.

In the event that these requirements are not met, the vehicle can only be driven to a parking or repair site. Repair of the malfunction is ensured by adjusting the cable tension with a special nut or replacing worn parts.

Replacing VUT on UAZ vehicles

The amplifier is removed on cars produced by the Ulyanovsk Automobile Plant according to the same principle as on VAZ cars. Let's consider replacing VUT using the example of a UAZ-31519 car:

first of all, we unscrew the two fastenings of the GTZ to the “vacuum”, usually the cylinder is secured with nuts 17, without disconnecting the brake pipes, we move it to the side;
under the hood, in the area of the windshield, unscrew the 2 bolts of the VUT amplifier bracket, the standard bolts are 14 mm turnkey;
in the cabin, at the connection of the rod with the brake pedal, pull out the cotter pin; for this you will need pliers;
remove the connecting pin;

the two lower nuts of the amplifier bracket are located in the car interior, they are turnkey 17, unscrew this fastener;

pull off the hose from the fitting of the device, dismantle the VUT;
disconnect the bracket from the “vacuum” - to do this, unscrew the four nuts (they are 17 mm);
the check valve is not included with the part, so we move it from the old VUT to the new one;
We connect the bracket to the new amplifier, carry out the assembly - we install all the parts in their places.

How to make a replacement?

Replacement is carried out using a set of keys and screwdrivers. The vacuum brake booster is located under the hood, so work can be done in the garage or outside. The replacement takes place as follows:

First you need to disassemble the wall of the VAZ 2110 engine compartment, then remove the frill. This element is attached using a seal and upholstery;

Important! The most unpleasant moment in dismantling the vacuum brake booster is unscrewing the four nuts in the interior. To get to them you will have to remove several elements of the dashboard.

Features of repair of UAZ vacuum amplifiers

Unlike the vacuum amplifiers of VAZ cars, the VUT housing on UAZ cars is very durable, and it is not at all easy to halve it. You can bend the protrusions using a pry bar and a hammer, but this way the work is done in violation of the technology - according to the instructions, you need to rotate one half relative to the other. The biggest problem during disassembly is the “halving” of the body - sometimes these parts boil so much that it is impossible to disassemble the assembly. Car owners are advised not to press one body into another under any circumstances - then turning will definitely not work.

Another problem in repairing “vacuum units” is the low quality of spare parts in the repair kit; sometimes the installed parts are not enough for six months. Motorists advise not to do repairs, but to buy a new spare part, although there is another disadvantage - VUT for cars like UAZ-469 or UAZ-452 is not cheap, about 3 thousand rubles. As an option, you can pick up a “vacuum” from a foreign car at a car disassembly shop, whose mountings fit the main brake cylinder, and install it on the car by fitting it. The result is cheaper and more reliable - imported parts, even in used condition, last for several years without any complaints.

How to adjust the brake system on a VAZ 2110

In theory, the parking system should be able to hold the VAZ 2110 when the surface is tilted up to 25%. If it can’t cope, don’t rush to a car repair shop, where you’ll have to shell out a hefty sum - you can provide first aid to your car yourself:

The tensioner locknut must be loosened.
Then we tighten the cable.
We check the full stroke of the lever (it should be 2-4 teeth per sector).
Tighten the locknut more tightly.
To be on the safe side, we perform several brakes, checking at the same time whether the stroke of the lever has changed.

In this simple way you can check how well the vacuum brake booster works on a VAZ 2110.

The wheels should rotate without effort, with the lever fully lowered.

Source

Adjusting the rod of the vacuum brake booster UAZ

Often, after replacing the VUT, problems appear, and the car no longer brakes as well as it did before with a working “vacuum system” - the brake pedal takes off at the very end, or the system does not fully release the brakes. The whole point here is the rod that presses on the GTZ piston - it may not be adjusted from the factory. This rod has an adjusting screw, which is secured with a locknut. On UAZ cars (we don’t take the “Patriot” model into account), we check the rod adjustment as follows:

push the rod all the way back;
take a metal ruler or feeler gauge to adjust the valves and lay it along the body;
We measure the protrusion above the body with a caliper - the rod should extend approximately 7.8-8.0 mm;
if this distance does not correspond to the norm, loosen the lock nut and use the adjusting screw to increase or decrease the length of the rod;
Having established the desired size, fix the screw with a lock nut.

Even on the UAZ Hunter, the pedal can “take” at the very end, and it has a large free play. It is necessary to pay attention to the position of the pedal - if it is too low from the floor in the cabin, it needs to be adjusted:

unscrew the brake light mounting nuts on the brake pedal;
disconnect the wires from the brake light sensor;
Use two 19 mm nuts to raise the pedal, press the brake to check the free play, and if the pedal is adjusted normally, tighten the nuts.

↑ Brake light adjustment

If the brake light switch is too close to the pedal, then it does not return to its original position, valve 9 (see Fig. 7–2), pressing against body 22, separates cavities A and E, and the wheels are incompletely released when the pedal is released.

The position of the brake light switch is adjusted by moving it when nut 5 is released (see figure). Install it so that the brake light buffer lightly touches the pedal stop, while the pedal free play should be 3–5 mm. After completing the adjustment, tighten nut 5.

WARNING! Adjust the free play of the brake pedal with the engine not running.