Brake condition check (VAZ-2101)

VAZ cars can reach high speeds, so the driver must be sure that the brakes will come to the rescue at the right moment and will not fail.

There is no unit, mechanism or assembly in a car that is more important than the brakes, and this imposes special responsibility during their inspection and maintenance. VAZ cars have combined brakes. The front ones are disc brakes, and the rear ones are drum brakes.

When the brake pedal 6 (Fig. 28) is pressed, the master cylinder pusher moves the piston. The compressed brake fluid moves through the tubes to the wheel cylinders of the front 3 and rear 10 brakes. The pistons of the wheel cylinders, experiencing the pressure of the fluid, press the pads against the disks or drums. If the hydraulic booster 5 is included in the hydraulic drive circuit (in VAZ-2103 vehicles, VAZ-2105, VAZ-2106, VAZ-2107, VAZ-2121), then as the force of pressing the brake pedal increases, it comes into operation, which makes the driver's job easier. It is very important that the front and rear brakes have separate drives. This means that a malfunction of the rear brakes does not leave the car without brakes at all.





The brakes of other VAZ models are noticeably different from the brakes of the VAZ-2121 "Niva". The all-wheel drive vehicle naturally has a shortened wheelbase and a higher center of gravity. These design features have a noticeable effect on the distribution of loads falling on each axle during braking. In the VAZ-2121 "Niva" under particularly difficult conditions, the front axle and separate drives for the front and rear brakes turned out to be not as effective as on all other models.

It was necessary to use a special hydraulic drive scheme on the Niva (Fig. 29), with which the front disc brakes are always operational. The design of the front brake itself has also undergone some changes. If traditional disc brakes are made with a fixed caliper (fig. 30, a), then for the first time in the domestic automobile industry, the Niva uses a design of front disc brakes with a sliding caliper (fig. 30. b), which ensured a tight arrangement of the hubs and wheel brake mechanisms.





However, all the positive things that have been said about brakes only become effective with constant attention and care. No maintenance should be done without checking the condition of the brakes.


The free travel of the brake pedal 4 (Fig. 31) with the engine off for VAZ-21013, -2103, 2105, -2100, -2107 and -2121 "Niva" cars should be 3-5 mm. These millimeters can be obtained by adjusting the switch 1 of the brake light. To do this, loosen the nut 2, set the brake light switch so that its buffer 3 slightly touches the pedal stop. Achieve the desired free travel and tighten the nut.



Now let's talk about the front brakes. They are disc brakes (Fig. 32), because when braking, most of the load falls on the front axle, and disc brakes have a much greater braking effect. To find out if the vacuum booster is working, press the brake pedal 5-6 times with the engine off. Then press the pedal and stop halfway through its travel and start the engine. If the vacuum booster is working, the pedal should move forward. If this does not happen, you need to look for where the air is being sucked in.



The thickness of the linings of new brake shoes is 11 mm, and they can work until they become 1.5 mm thick. After that, they are replaced with new ones. To find out what condition the linings 4 are in, the wheels must be turned to the left and right sides and the right and left brake shoes must be inspected accordingly. If the linings of the shoes are worn out, prepare to perform the operation of replacing the shoes.

Tools and accessories for this operation: screwdriver, pliers, hammer, flashing tool, mounting blade, combination wrench for removing wheels, wire brush, jack, wheel stops, syringe, container for brake fluid. Since the wheels will have to be removed, you need to make sure that the car is on a level surface with the parking brake engaged. Having placed stops under the wheels, hang up one of the front wheels with a jack. Using a combination wrench, unscrew the wheel mounting bolts and remove it. Replace the pads with new ones in the following sequence:

• using a metal brush and wiping ends, remove dirt from the caliper 2;
• pliers are used to remove the cotter pins that secure the fingers 9;
• using a firmware or an old finger that has served its time and a hammer, knock out the finger. The fingers almost always offer stubborn resistance. Usually a rag soaked in kerosene is placed on such fingers for 15-20 minutes. The fingers are removed together with the springs 7;
• remove flat springs 8 pads 10;
• the mounting blade is used to move the pads away from the disk 3. Before performing this operation, a small amount of brake fluid must be removed from the reservoir with a syringe. This should be done because the separated pads will move the pistons 6 into the cylinders 5, and the fluid displaced by the pistons will rush into the reservoir and may spill out;
• using pliers, carefully remove the pads 10 from the caliper (by finger to touch) check the condition of the rubber cuffs 1.

New pads are installed in the reverse order. Those who took into account the recommendations and lubricated the pad pins before starting to operate the car will not have any difficulties when dismantling them. It is advisable to lubricate the pins and sockets each time the pins are installed.

You just need to be careful that the lubricant does not get on the surfaces of the pads and disc.

The rear wheel brakes are drum-type, with one wheel cylinder and two shoes (Fig. 33). Replacing the shoes with new ones is not a difficult operation, if not for one "but". Removing the drums can be very difficult even in a service station. Numerous tips and suggestions were put forward on how to remove the drums, but, unfortunately, there were no truly effective ones among them.



Of all the devices proposed recently, the most effective was the puller (Fig. 34), made by a Cherepovets car enthusiast from a piece of an old spring. The bent edge of the lever 3 is hooked onto the edge of the drum 1. A steel rod 2 is inserted into the hole on the device and, resting it against the end of the axle shaft, the drum is moved from its place.



The operation is considerably simplified if the contact surfaces of the drum hole edges and the axle flange are lubricated before operation. In this case, it is sufficient to use two bolts, which are screwed into the technological holes until the drum moves from its place.

Once the drum is removed, replacing the pads is not particularly difficult (see fig. 33):

• first, disconnect the end of the cable 9 from the lever 3 and remove the lever;
• disconnect tension springs 5 and 8;
• cups 1 of the pivot posts are turned and removed together with the posts, springs and lower cups;
• remove the pads 2, removing them from the grooves of the pistons of the wheel cylinder 4;
• remove the spacer bar 6.

Install new pads in the reverse order, taking into account that when installing the pad, it is necessary to first put the pad drive lever axle in place, and mount the spacer bar after installing the support posts. After replacing the pads, it is imperative to adjust the position of the pads using eccentrics 7.

The parking brake (Fig. 35) is an integral part of the vehicle's braking system. Its role is great. How many exciting stories can you hear about the parking brake playing the role of a savior? Mountain dwellers can truly appreciate its special role. But for the parking brake to really serve you well, it must be adjusted correctly. The adjustment status is most conveniently checked on a natural slope. Park the vehicle on such a slope (30°), tighten the brake lever three to five clicks and see what happens next. If the vehicle does not slide down, then everything is in order. Otherwise, the lever stroke must be adjusted and the operation must be performed with a 13 mm wrench and pliers on an inspection ditch or on an overpass in the following order:

[The original is posted on Internet resource: VAZBOOK.RU]

• move the parking brake control lever to the extreme lower position;
• pull the lever up two clicks and from below (from the groove) with a 13 mm wrench and pliers loosen the lock nut 3;
• turn nut 2 to tighten cable 1, then lock nut 2 with the lock nut.

If air gets into the hydraulic brake drive system, this is already an emergency. First of all, it is necessary to find the cause and eliminate it. Air can get into the system if individual parts and units were replaced. Once in the system, air begins to distort the force transmitted by the fluid. In any case, air must be removed from the system. This operation is simple, but requires at least two participants and it is advisable to perform it on a ramp or inspection ditch. To perform the operation, you will need: an 8 mm open-end wrench, which was suggested to be made or purchased for unscrewing the screws of the contact plates of the breaker-distributor, a rubber hose included in the tool kit, a container for brake fluid and 0.25-0.30 kg of the Neva fluid itself, wiping material.

Before starting the operation, it is necessary to fill the tanks of the main cylinders with brake fluid to the normal level, i.e. to the lower edge of the filler hole, and clean the caps of the nipples intended for bleeding the system from dirt. Be careful with the caps. It can be said about them that "the valve is small, but precious". Only thanks to them the holes of the nipples do not get clogged with dirt. The caps are often lost, and if you find that, you need to clean the holes and put a cap of your own making on the nipple (from a piece of rubber hose with the end tied with wire).

Removing air from the system is performed by two people in the following sequence (Fig. 36):

• an 8 mm wrench is placed on the hexagon of the fitting 1;
• one end of hose 3 is placed on the head of the fitting, the other is lowered into vessel 2 with brake fluid;
• one person standing in the inspection pit unscrews the nipple by one and a half to two turns, and another person sitting in the car at this time sharply presses the brake pedal, then smoothly releases it and sharply presses it again. This action must be performed until air bubbles stop appearing;
• as soon as the bubbling stops, you should press the pedal and hold it in this position until the person below tightens the nipple all the way.

The operation must be repeated on each wheel and each time before starting to bleed, add brake fluid to the norm. The fluid drained from the system can be reused, but first it must be settled and filtered.

If the fittings have not been touched for a long time, it may happen that an elegant open-end wrench will only dent the edges of the rusted fitting and nothing more. The way out of this situation is to use an 8 mm socket head from a set of heads. You cannot just put the head on the fitting. It must be prepared, i.e. turned on one side as shown in Fig. 37.



A few words about the pressure regulator 2 (Fig. 38) of the rear brakes. It serves to regulate the braking force of the rear wheels depending on the load on the rear axle and the road condition. The sharper the braking, the greater the share of the total mass on the front wheels. Since the rear axle is unloaded, the force of the rear brakes may be greater than the force of adhesion of the wheels to the road surface, and this, in turn, can cause wheel slippage, and therefore low braking efficiency, loss of control, skidding. The presence of a pressure regulator eliminates this drawback by automatically changing the pressure of the brake fluid in the hydraulic drive of the rear wheels. Violation of the location of the pressure regulator distorts its operation and practically reduces its capabilities to zero.



The lack of necessary information about the pressure regulator leads to the fact that it is not paid attention to at all. Whether it works or just takes up space - few people care.

Experience shows that the neglect of the pressure regulator 2 is not only on the part of car owners, but also on the part of specialists at most service stations. To control the correct position of the pressure regulator on the body, a special device is needed, simple, but not available for sale. At the service station, such a device is available, but for some reason it is ignored, and in vain.

Over time, piston 4 of the regulator becomes immobile and rusty, so it is important to be able to independently check the functionality of the pressure regulator.

Place the vehicle on an inspection pit, clean the regulator and protective cover 3 from dirt and carefully remove the protective cover; wipe dry the torsion-piston connection; while your assistant is pressing the brake pedal with force, you watch the protruding part of the piston. If the pressure regulator is working properly, the piston should move (0.5-0.9 mm) and start twisting the torsion lever 1. To be sure, make sure again and again that the piston is moving.

Having found that the pressure regulator is fully functional and there is no brake fluid leak, lubricate the protruding part of the piston with DT-1 or Litol-24 grease (put 5-6 g of this grease into the protective cover and install it in place). If the piston is rusted, the pressure regulator must be replaced.