The effectiveness of the vehicle's brakes is of great importance - if the braking system is not applied effectively, an accident can occur. To make the brakes clear, at all modern cars the amplifier is installed, it provides an instant stop vehicle when you press the pedal.
Repair of the vacuum brake booster is necessary if the brakes become “wadded” and the pedal has to be pressed with great force to brake.
Repair of the vacuum brake booster VAZ 2106, 2107, 2108, 2109, 2110
Vacuum booster brakes (abbreviated - VUT) of VAZ cars facilitates the driver's work - it enhances the effect of pressing the pedal in the braking system (TC). This assembly consists of the following main parts:
- valve;
- metal case;
- diaphragm;
- piston;
- stock;
- 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 main brake cylinder is installed on the side where the vacuum is created. Vacuum (vacuum) is created by connecting this part of the body with 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) by means of a rod and a piston when pressing the brake enhances the braking effect, thereby making it easier for the driver - there is no need to press the pedal with great force. After releasing the pedal, a powerful return spring allows the diaphragm inside the body 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 work.
On cars VAZ-2106-07 and VAZ-2108-10, brake boosters of different appearance are installed, 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 through” (falls under the pressure of the foot), the VUT works.
The main malfunction of the vacuum booster is damage to the diaphragm. When the diaphragm has ruptures, air flows from the outside of the housing into the vacuum cavity, and no vacuum is generated in the device. But the malfunction may not necessarily lie in the device itself - often VUT does not work due to air leaks or for other reasons:
- the "vacuum" check valve is faulty;
- air is leaking from the hose connecting the intake manifold with 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 cars is connected by a hose to the fourth cylinder of the engine.
Repair of the VAZ 2106, 2107, 2108, 2109, 2110 vacuum brake booster should begin with dismantling this unit, then the VUT must be disassembled.
VUT on a VAZ-classic car is removed quite simply, and if you have minimal locksmith skills, this work is easy to do. We remove the node as follows:
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:
Usually, the VAZ-2109 vacuum amplifier repair kit contains a diaphragm, a cuff, a boot, covers (2 pcs.) And a valve. All parts should be changed so that later you do not have to redo the work. When assembling the vacuum amplifier, it is better to immediately fix the diaphragm to the plastic casing, so it will be easier to mount the unit. 
Which side of the spring is placed does not matter, but when assembling the amplifier, you will have to make an effort to get the holes in the housing onto the studs.
Repair of the UAZ vacuum brake booster
Malfunctions of the vacuum amplifier of UAZ vehicles can be determined by the following signs:
- the engine is troit, and since the vacuum hose goes to the manifold of the first cylinder on "Uaz" motors, if the VUT is faulty, this particular cylinder is not modified;
- a hiss is heard under the hood - the diaphragm is poisoning the air;
- the brake pedal is rigid and does not squeeze when starting the engine;
- there are wet smudges between the GTZ and the amplifier (brake fluid is flowing).
If there are smudges of "brake" 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 amplifier, most likely, the VUT will also have to be repaired.
Another one frequent malfunction in the brake system - failure of the check valve. This simple mechanism is very easy to check - you need to blow into it. The valve must be blown freely in one direction (when supplying rarefied air from the manifold), and in the opposite direction the air goes hardly. If the valve is faulty, it is blown freely in both directions.
The amplifier is removed on cars produced by the Ulyanovsk Automobile Plant according to the same principle as on VAZ cars. Consider the replacement of VUT using the example of the UAZ-31519 car:
the two lower nuts of the amplifier bracket are located in the passenger compartment, they are on a turnkey basis for 17, we turn off this fastener; 
Features of repair of UAZ vacuum amplifiers
Unlike the vacuum amplifiers of VAZ cars, the VUT body on UAZ cars is very durable, and it is not at all easy to halve it. You can bend the protrusions with a pry bar and a hammer, but this is how the work is performed in violation of the technology - according to the instructions, one half must be turned relative to the other. The biggest problem during disassembly is the "halving" of the case - sometimes these parts boil so much that it is impossible to disassemble the unit. Car owners of cars advise in no case to press one body into another - then turning will definitely not work.
Another problem in the repair of "vacuum cleaners" 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 here - VUT for cars such as UAZ-469 or UAZ-452 is not cheap, about 3 thousand rubles. Alternatively, you can pick up a "vacuum" from a foreign car at a car dismantling station, which has a master brake cylinder for the mountings, and install it on the car by fitting. As a result, it is cheaper and more reliable - imported parts, even in a used condition, serve for several years without any complaints.
Often, after replacing the VUT, problems appear, and the car does not slow down as much as it used to be with a working “vacuum cleaner” - the brake pedal picks up at the very end, or the system does not completely release the brake. The whole point here lies in the rod, which presses on the GTZ piston - it may not be adjusted from the factory. This stem has an adjusting screw that is secured with a locknut. On UAZ vehicles (we do not take into account the Patriot model), we check the rod adjustment as follows:
Still on UAZ Hunter the pedal can "take" at the very end, and it has a large free travel. It is necessary to pay attention to the position of the pedal - if it is too low from the floor in the passenger compartment, it must be adjusted:
One of the reasons for the decrease in the braking efficiency of the car may be the unsatisfactory operation of the vacuum booster. The vacuum booster is also checked in the event of a noticeable increase in effort when pressing the brake pedal.
The vacuum booster is installed between the brake pedal mechanism and the brake master cylinder. When braking, due to the vacuum in the reservoir of the engine, it creates an additional force proportional to the pedal force through the rod and the piston of the first chamber of the master cylinder.
A check valve is installed in the hose connecting the vacuum amplifier with the engine receiver, it maintains the vacuum when it falls in the intake pipe and prevents the air-fuel mixture from entering the vacuum amplifier.
Quick express check of the UAZ Hunter vacuum brake booster.
During operation, the vacuum amplifier does not require adjustments, and its maintenance consists in checking the reliability of the fastening. For a quick express check of the amplifier's performance, it is necessary to press the brake pedal several times all the way to the stop when the engine is not running, and then, keeping the pedal pressed, start the engine. Due to the difference in pressure values in the cavities of the amplifier, the brake pedal should lower slightly and move forward.
If this does not happen, then it is necessary to check the integrity of the hose and the tightness of its connection with the check valve of the vacuum amplifier and the intake pipe of the engine, and, if necessary, eliminate. If this does not give a positive result, then the amplifier is faulty and must be repaired or replaced with a new one.
Checking the vacuum brake booster for leaks.
Checking the vacuum amplifier for tightness is a more time-consuming process. Open the hood of the car and start the engine for one to two minutes, then about thirty seconds after stopping it, press the brake pedal twice. During this action, the characteristic hiss of air entering the vacuum amplifier should be heard.
Additionally, check the check valve of the amplifier; if it is faulty, the vacuum in the vacuum cavity of the amplifier does not remain when the load on the engine changes or when it stops. To check the valve, disconnect the vacuum hose from it and remove the valve from the rubber seal of the amplifier flange.
Slide any suitable rubber bulb, such as a hydrometer, onto the short, larger diameter check valve fitting and squeeze it. If the check valve is working properly, the bulb will remain compressed. If the bulb straightens out, replace the valve and repeat the procedure for checking the vacuum booster.
If during the verification process it became clear that the vacuum amplifier is faulty, then it is easier to replace it with a new one, since repairing the amplifier is very laborious, requires appropriate knowledge and skills, the use of special installation and adjustment equipment, and does not always end successfully.
Free travel of the brake pedal with the engine off should be within 5-14 mm. Too little free play indicates a jammed working cylinder and provokes increased consumption fuel and accelerated wear of brake pads. Too much free play is a sign of increased gaps in the pedal mechanism or a leak in the hydraulic drive.
On UAZ Hunter cars with engines of ecological class Euro-2 and UAZ-315196 cars with the conditional marketing name UAZ-469 New.
Free travel of the brake pedal is regulated by setting the stop switch of the brake signal to the position providing free travel of the pedal within 5-14 mm.
On UAZ Hunter cars of Euro-3 ecological class.
Pedal free travel is set by turning the adjusting screw, choosing the gap in the connection: the fork of the vacuum booster pusher - the finger - the brake drive lever. Free travel should be within 5-14 mm. The position of the brake signal switch is adjusted separately using the adjusting nuts so as to provide a clearance of 0.5 mm between the switch stop and the buffer.
On UAZ Hunter cars of Euro-4 ecological class.
Free travel of the brake pedal is regulated in the same way as for ecological Euro-3, with the difference that the free travel of the brake pedal must be within 5-8 millimeters.
The pressure regulator must be checked periodically during operation. When checking, by external inspection, it is necessary to make sure that there is no damage to the regulator and its drive parts, there is no leakage of brake fluid and gaps in the connection of the rack with the elastic lever and bracket on.
When you press the brake pedal, the pressure regulator piston should move out of the body by 1.7-2.3 mm. Lack of piston travel, as well as insufficient or excessive piston travel, indicate a malfunction of the regulator or its drive.
When inspecting, special attention should be paid to the location of the control plug and the absence of brake fluid leakage from under it. In normal condition, the plug should be recessed into the opening of the regulator body until it stops. The protrusion of the plug from the hole and the leakage of brake fluid mean a loss of tightness of the seals, and a malfunction of the regulator. In this case, it must be repaired or replaced.
Checking and adjusting the force of the elastic lever on the piston of the pressure regulator must be carried out periodically during operation and always when replacing the rear ones with new ones or with a large amount in the package.
The adjustment is made as follows:
1. Place the equipped vehicle on a level, firm, horizontal platform.
2. Loosen the adjusting bolt locknut, unscrew it 2-3 turns and tighten until it touches the regulator piston shank. Then tighten the adjusting screw:
- for UAZ Hunter cars with awning: 2 / 3-1 turn, 4-6 edges of the bolt head
- for UAZ Hunter cars with an iron roof: 1 or 1 and 1/3 turn, 6-8 edges of the bolt head
3. Tighten the lock nut and check the piston stroke of the regulator, it should be within 1.7-2.3 mm
A complete check of the correctness of the adjustment is carried out when the car is moving on a straight horizontal section of the road with a dry asphalt surface. In the process of movement, brake the car until the wheels lock.
With a working pressure regulator and a properly adjusted drive, there should be some advance in the locking of the front wheels relative to the rear ones. In the case of advanced locking of the rear wheels, it is necessary to additionally unscrew the adjusting bolt by 1-2 edges of its head and then repeat the check while the car is moving.
The vacuum booster is designed to create additional force applied to the master brake cylinder rod. The vacuum in the brake booster is created by the reduced pressure in the intake manifold.
The vacuum booster cannot be repaired and is replaced in the event of a malfunction. If an unusually large pedal force is required to achieve sufficient braking while the engine is running, check the brake servo.
Check of the vacuum amplifier, carry out in the following order:
Press the brake pedal 5 - 6 times with the engine off to create the same pressure in the vacuum and atmospheric chambers of the vacuum booster, close to atmospheric (remove the vacuum discharge);
Keeping the brake pedal depressed, start the engine;
With a working vacuum booster, the brake pedal after starting the engine should "go forward" and weaken the resistance force on the leg;
If the brake pedal does not "go forward", check the tightness of the connecting hose between the inlet and the booster, or the serviceability of the vacuum booster itself.
A non-return valve may also be the cause of a malfunction of the vacuum booster. Using a screwdriver, carefully squeeze out the valve and blow it in the direction of the arrow, which is stamped on the valve. Purge air must exit from the other side of the valve. If you blow against the arrow stamped on the valve, then the air, on the contrary, should not come out from the other side. When installed, the valve is pressed into the brake booster.
Removal and installation of the vacuum booster without installed ABS system
Withdrawal- carry out the vacuum amplifier in the following order:
Remove the “-” wire from the AB terminal;
Remove the noise insulation located in the engine compartment of the engine;
Remove AB;
Take off expansion tank cooling systems;
Disconnect the multi-pin connector for the coolant temperature display and remove the two bolts;
Unscrew two bolts and remove the right partition of the AB compartment;
Unscrew one bolt and remove the left rear AB compartment bulkhead. Set the expansion tank aside;
Disconnect the connector block on the brake fluid reservoir cap and unscrew the reservoir cap;
Using a siphon-pear, pump out the brake fluid from the reservoir and remove the master brake cylinder;
Disconnect the vacuum hose going to the brake booster;
Remove the driver's side instrument panel lower casing;
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Vacuum brake booster
Other questions about the brake system
The creak of the brakes of the UAZ is its integral attribute. One might get the impression that the pads were worn down to the rivets, but this, as a rule, is not the case and the squeak occurs due to dirt on the pads and the brake drum. Strong braking (but not with skidding) at high speed helps a little. As a rule, the remainder for passes without squeaking. Personally, I am not worried about this, on the contrary. This squeak works better than a beep, especially if someone is clipping.
I lost the whistle after replacing all the cylinders with. From which I can assume that the nature of this phenomenon lies in the uneven distribution of the load on the pads when using standard cylinders. Them, how not to adjust, and after a few braking gaps become different.
I somehow read some advice from experienced people in the ZR for a long time, it is necessary to drill two or three holes in the brake lining as thick as a pencil rod and insert these very rods there, so it was stated that all the creaks are due to the properties of graphite.
- Mark and remove ALL brake drums and measure their diameter with vernier calipers. As a result of uneven wear or grooves, this size can walk within a fairly large range - hence the unevenness. Check if the brake fluid or transmission is leaking somewhere. If it flows, eliminate it.
- Make two pairs of them - for the front and rear axles- with the same (within 0.2-0.3 mm) diameter.
- Mark and remove pads. Rinse and clean them and all parts of their suspension.
- Assemble so that the pads work "on their" drums. Adjust carefully.
- Take a day ride around the city.
The trick is that the VUT GAZ-2401 comes in a separate unit (not at the pedals), but my pedals are lower and therefore I don't want to redo the pedal assembly.
There are no problems with the installation. From ch. brake cylinder tube to the amplifier, from the amplifier tube to the circuit separator, and from the latter two tubes - one to the front wheels, the other to the rear. Intake manifold vacuum. There is also a loop detector (optional) - see doc. for GAZ-24. Doubts arise about the fair passage of the inspection. And, it seems, he is rather weak for the UAZ, but still better than without him.
Description of the hydraulic brake drive circuit:
1. the main brake cylinder;
2. alarm indicator;
3. sleeve with a diameter of 12 x 26, connected to the intake manifold of the engine;
4. hydraulic vacuum amplifier (24-3550010);
5.brake separator (24-3575010);
6. connection for pumping the hydraulic vacuum amplifier;
7. control lamp;
8. brake cylinders of the rear wheels;
9. brake cylinders of the front wheels;
10.Air filter of the hydraulic vacuum amplifier.
Bleeding the brake system with the installed hydro-vacuum brake booster GAZ-24. Fill the master brake cylinder with "BSK" or "Rosu" fluid (do not pour "Neva", it is not compatible with GAZ-24 brakes, it is also not allowed to mix BSK and Rosu), turning the valve in the separator by 2-2.5 turns brakes, we pump alternately the brakes of the rear and front wheels, then the hydraulic vacuum booster. We wrap the separator bleed valve with the brake pedal released. As always, doing this work, add fluid to the master brake cylinder so that air does not enter the system. If all brakes and their drive are correctly adjusted and there is no air in the system, the brake pedal, when pressed with your foot, should not go down more than half its travel, and the warning lamp should not light up when the ignition is on.
I installed a vacuum brake booster from a BMW 7 90s (inflated). The only thing that is needed in advance is for the turner to grind the adapters (since the fittings of the UAZ brake pipes differ in size and thread with holes on the main brake cylinder BMW-7). I also removed the reinforcing plate on the engine side panel and replaced the working self-regulating brake cylinders with GAZ-24 (). The brakes are much softer and more efficient. The amplifier has been working for four years, during which time I did not even climb or disassemble it.
Volgovskiy brake cylinders, starting from 24 (since 1970), are all self-feeding, no manual adjustment of the pads is needed and less effort is required when braking. Back UAZ fit exactly from 24 (32 mm), because on 2410, 31029, ... (I mean the rear cylinders) a different thread for the brake pipe (without an intermediate bolt). On the front- from 2410 or 24 (the first is better - they have foam inserts, which must be slightly impregnated with BSK or castor oil, which prevents corrosion). Beware of the "left" - South Port is full of them. The main difference is appearance: anthers do not "shine", irregularly shaped, often rust under the anthers. You can also change the pads themselves - the effort will decrease slightly, and most importantly, the mileage will increase. They are glued and work until almost complete wear and tear.
After alteration, the brakes need to be pumped MORE THOROUGHLY, because because of the locking ring, this process is "delayed" a little.
After much thought and reading the statements of smart people (see the above note by CHIF), I came to the conclusion:
Front- GAZ-3102 they are GAZ-2410 they are the same .... (they are all the same) diameter 32. No alterations. I took it and put it on.
Rear- GAZ-3102 they are also GAZ-2410 diameter 28. With a transitional fitting.
I was looking for fittings for a long time. There are no UAZ vehicles from GTZ 3160. The solution was found unexpectedly when looking at the display case in the storage shed. Transition union 6x5 rear working brake cylinders Moskvich. From a conversation with the seller, I learned that the Muscovite working brakes on the 412th had been gone for a long time. There is only 41st. And they have the same trouble - on the 41st x5, and on the 412th x6. 10 rub. issue price. Moskvichevsky adapter into the Volgovsky cylinder, into it our adapter (6x6 to another thread), and into our adapter a tube.
Then nadot. Wrench x12 to twist the fittings. To bleed the key for 10 of the cap brake (at the Volgovskih choke x10). A set of copper washers for the front cylinders (it is better not to put the old ones), 6 pieces per wheel. Well, remember about the possibility of folding the tubes.
The cylinder must be disassembled before installation. Well, or at least bend the anthers. And now there are a lot of such - seemingly normal, but inside it is rusty. And yet - in the store they are not very carefully overloaded. When I was choosing myself, I did not find ANYONE (!) With a whole anther. I had to buy it separately.
There are different cylinders in stores that suit us:
From 3102
- very often, under their brand name, there are native UAZs, quite even NOT self-powered.
From GAZ-24, they are from 3302 - get up without problems, like relatives. The only negative - on an empty car, the back is enough before the front - in theory, a regulator is needed, but there are no special problems (I have been driving for the 5th year already.)
From 3160 and from GAZ 2410- smaller diameter than 24 or 3302, but to dock them with our tube you need an adapter - GTZ fitting from 3160 (normally these cylinders are for 5 mm tubes.)
I installed all FENOX cylinders. In the store, I compared the factory-made rusty and sagging carvings and the neat FENOX.
It is necessary to cut out rings with a diameter of the RTC out of 10mm foam rubber, soak them with either castor oil or brake fluid, and put them under the anthers of each RTC.
And at the gas station I saw an UAZ with front disc brakes ... it was very clearly visible through alloy wheels... and the owner said that everything from the "Volga" got up almost like a native, only the disks were sharpened (or grinded) ... and he also said that the car stopped trying to rebuild when braking into the next lane.
We installed disc brakes from 3160 on the UAZ 31512 of our girls-jeepers. For installation on civil bridges needs a case steering knuckle 3160, caliper (2 pcs), brake discs and brake hoses. The hubs were fitted with 40 mm spacers.
Bottom Brakes - Extended Pedal Travel
A feature of my car is the lower position of the pedals. Over time, there were signs double squeeze brakes. Breeding the pads and bleeding did not give anything - the free travel of the pedal was 50-70 mm. ... I read from the lyrics about the grinding of the RTC and GTZ, about the rubber bands, about brake fluids... Armed with knowledge, he went to the garage. Breaking - not building, so I removed all the working cylinders, tormented with the long GTZ mounting bolts at the bottom (I had to use a gas wrench), and took it off too. The sight was not the most joyful, so I got down to work. I took a long hairpin, on which I put several squares cut out of felt, and secured them on both sides with nuts and washers. On a lathe, they made me something from this composition, very similar to a cylinder. By tightening the nut from below (be sure to counter-nut), thus tightening the cylinder, you can adjust the diameter of the cylinder, which in my case was 32 mm. I had to mess around for a long time, about 25 minutes per cylinder and constantly adding GOI, but the result exceeded all expectations: the cylinders became mirrored. The history of the brakes was also revealed - there were snacks, so I had to polish the pistons too. 
I collected everything, began to fill the hydraulic drive with (new) fluid. For some time, it was possible to fill and pump, identifying leaks along the way, but the pedal picked up at the very bottom. The pads and fingers were spread over the UAZBUK and the book. The free wheeling remained, there was a feeling of springiness, as if the system had air. I had to crawl under the car and carefully examine the entire kinematic diagram. Here the main surprise awaited: the pedal really picked up at the very bottom, so the remainder of the piston stroke was not enough for any normal operation. It turned out that during the service two holes became oval. One is located on the brake pedal ear and the other is in the U-bolt. For this reason, the pedal went freely through two oval holes, which together gave such a large stroke. Removing the parts from the car, welding the holes and drilling new (round) ones :), it was possible to completely get rid of the pedal failure. Now the brakes grab at the very beginning, which is very pleasing.
The main factor of malfunction of the vacuum brake booster is its complete or partial inability to create a vacuum in the working chamber. A potential source of the problem is an open or depressurized hose connection between the engine intake manifold and the amplifier.
Interference in the operation of the unit is also caused by defects inside the amplifier - due to a violation of the integrity of the working surface of the diaphragm or loss of elasticity by the valve. In order to detect malfunctions of the vacuum brake booster, certain tests are carried out.
Methods and signs of detecting malfunctions of the vacuum brake booster
- For example. Start the engine and turn it off after a few minutes. Then press the brake pedal some times with the usual effort. With a working amplifier, at the moment of the first pressing, the pedal will be pressed, as expected, all the way. The system will work, and the created vacuum will attract the diaphragm, which helps to push the piston of the brake master cylinder through the piston rod.
Then the valve will equalize the pressure in the chamber with the atmospheric one. During the second and subsequent presses of the pedal, there will be no place for the discharge to take, which is why the pedal travel will become less and less. If there is no difference between the initial and further pressing on the pedal, then it is clear: this device does not provide additional force in the master brake cylinder.
- Following the experience done, it is worthwhile to perform another one. The engine is off. The brake pedal has been pressed several times in a row. Her move testified to something. Either the results of the experiment seemed inconclusive, or there was a desire to make a control approbation. The following actions are performed. The brake pedal is depressed and the engine starts when the pedal is depressed.
With a working vacuum amplifier in its vacuum chamber, a vacuum is formed, due to which the membrane presses on the rod, the rod pulls the pusher connected to the pedal, and the latter is slightly lowered.
In the case when the pedal remained in place, the conclusion is drawn: the expected chain of events did not take place due to a malfunction of the vacuum brake booster. Such checks reveal significant damage to the part.
- Another test makes it possible to determine the presence of small air leaks. With the car engine running, press the brake pedal, then, without releasing it, turn off the engine. Hold the pedal in the same position for half a minute.
Due to the leakage of the amplifier, the pressure in the vacuum chamber will increase. The diaphragm, under the influence of the return spring, having lost the support of the force that balances its position, will press on the pusher and raise the brake pedal.
If this is not observed, then there are no malfunctions, and the vacuum brake booster is working normally. In any case, if there is a need to repair any brake unit, it is taken into account that there may not be a second chance for a repair, therefore, they turn to car service professionals for assistance in diagnostics and repairs. They can produce.
