Rear brake drums: Removing and replacing

Many modern cars are equipped with disc brakes in front and behind. But they also manufacture machines where rear brake drums are used. This mechanism has been used in the automotive industry for over a hundred years. Like many other elements, such a brake system can wear out, and then it is necessary to dismantle and replace these parts.

Design

The drum brake rear is a few details. This is a rotating drum and brake pads. In the process of braking, the last rubs against the surface of the hollow inside the drum. In order for the pads to move, the design has special springs. They are compressed or released depending on whether the driver presses the brake pedal or releases it. The brake cylinder responds to the activation of the brake pads - it presses the shoe under the pressure of the working fluid to the surface of the drum. These cylinders can be several. The entire mechanism is mounted on a stamped brake plate.

The drum brake rear can have another design - a belt. Here the braking is carried out by means of a flexible metal band, which stretches and contracts the drum. From this system in the automotive industry has long been abandoned.

Drum brake: the advantages of the solution

One of the main advantages of these mechanisms is that they are reliably closed from any environmental influences. This braking system is ideal for operation in severe or even extreme conditions.

The pads practically do not get dust and moisture, which significantly increases the life of the parts. Also, during the braking process, this system releases less heat, which makes it possible to use lower-cost, entry-level fluids with a low boiling point. Another advantage is that the braking force can be increased not only due to the larger diameter of the brake drum, but also due to its width. So, the contact patch of the pad with the surface of the element becomes larger, which allows to significantly improve the braking properties.

Rear brake drums due to its design can increase the efficiency of work. The drum rotates and during the braking process it constantly wants to remove the pads behind it, as if turning them. As a result, the pedal force is reduced.

Design Disadvantages

With all its advantages, such a braking system has a low response speed, unlike disk analogs. Also, there are certain difficulties in the configuration, the design is of low stability. When the rear brake drum is heated, it happens that the pads "stick", and the braking characteristics deteriorate significantly.

If the air temperature is too low, the handbrake is not recommended. It happens a lot of situations when the pads just freeze to the drum. Because of these troubles in most modern expensive cars from this mechanism prefer to leave.

Rear brake drums can be seen more often on budget models, on urban subcompacts, where they are installed from the rear. This system is also installed on a truck.

Problems: signs and causes

Since the rear wheels are much less involved in the braking process than the front wheels, the car owner does not immediately realize that the efficiency of their work has decreased. In addition, the decline in this very efficiency is gradual and slow.

Problems with the drum brake can be felt with vigorous braking - the car stops much slower than usual. On most machines, the failure of this system is particularly noticeable when necessary to move in reverse. The front brake system, which has become rear, does not want to work alone and stops the car inefficiently. Leaks of the brake fluid can lead to trips of one or two circuits of the brake system - this causes a decrease in braking performance by 30-60%. The air in the hydraulic drive leads to a feeling of softness when the pedal is pressed. And the brake works only at the end of the stroke.

If the drum skewed pads, the springs or racks broke, the driver can hear the scraping sounds. This can cause jamming and overheating of the drum. It can also lead to a reduction in the running speed of the machine or a high fuel consumption. Among the problems is also the ovality of the drum.

Types of malfunctions

Among the most common reasons for which the rear brake drums lose efficiency, not a decrease in the life of the pads, but an increased wear of the drum itself. Inside, on its working surface, the circle of this very surface increases. When the pads and the working surface are simultaneously produced, there is a risk that the pistons will squeeze out of the working cylinder, the wheels will jam or the brake fluid will leak from the circuit.

On vehicles with large runs due to corrosion, there may be weakening, "sticking" or breaking of the springs. The pressing force can be significantly reduced due to the weakening of the hand brake cable. Rarely, but there is a detachment of the friction lining from the shoe. In this case, it is recommended to replace the brake pads of the rear drums.

Troubleshooting

If there are traces of liquid on the surface of the working cylinder, this indicates that air enters the system. For accurate diagnosis it is necessary to go to the SRT, where there is a special stand that allows you to calculate the effectiveness of each mechanism. In order for the drum brakes to function properly, it is necessary to service them in time, to check their work. To do this, it is sufficient to stop abruptly from a speed of 60-80 km / h. These tests need to be conducted as often as possible.

Removing the rear brake drum: when necessary

The drum should be replaced if it is deformed or its surface has through cracks and dents. In addition to the deformation of this mechanism, its working surface can be worked out (the inner diameter of the element increases). The rear brake drum (VAZ 2101-2107) has a diameter of 200 mm. If the size exceeds 201.5 mm, the part must be replaced.

Replacement of a drum of brake system VAZ 2101-07

The replacement process should be carried out on the posted machine, with the hand brake must be released. The first thing to do is to remove the wheel from the side where the drum will be dismantled.

Then, using a nut or spanner, the guide pins should be unscrewed to hold the drum and attach to the wheel hub. When they are turned away, pull the drum body - it should be removed. If the rear brake drum (VAZ-2107 including) is not removed, which is very often the case, then it is necessary to wrap the two M8 bolts in the holes that they screw in. Wrap them evenly. As a result, the item will be amenable to removal.

VAZ 2108-099

To remove the rear brake drums VAZ models 2108-099, you need to include the first gear, as well as install the stop bars under the two front wheels of the car. It is important that the handbrake lever is released. Then remove the wheels of the car, and the brake mechanism is cleaned of dirt.

After cleaning, remove the two mounting pins, apply a little WD-40 to the wheel hub and clean the dirt and corrosion. With the help of a rubber or polymer hammer with light blows pull the drum off the hub. If the part does not want to give way, then with the help of pins or M8 bolts it is possible to compact the drum.

VAZ-2110

The rear brake drum VAZ-2110 can deliver the owner of the problem in the process of replacement or removal. The part is dismantled quite simply provided that the car is new. On old cars, the removal process entails problems. To work, you need a powerful hammer, a deep 7 mm head, and a ratchet. First of all, the bolts holding the rear wheel break. After the car is lifted by the jack, they finally turn away and completely remove the wheel. Now unscrew the studs on the drum. It is best to do this at a time when the machine is still on its wheels. You can also tighten the handbrake. Then, from the back side, the drum is knocked off the hub from the wheel hub. If it does not, then the studs help - they are screwed from the corresponding holes and when they are evenly twisted, the drum is dismantled.

In the same way, the drum of the rear brake is removed on Korean cars ("Nexia" is no exception). In some cases, it is necessary to use force, but more often after handling the WD-40, the contact position of the drum is perfectly removed.

"Renault Logan"

If a brute force was used to dismantle brake elements with VAZ cars, then in the case of Logan another method is used. The first transfer to the checkpoint is the first transfer. Then, the chocks are folded under the two front wheels. Further, dismantling of decorative caps, if they are on wheels, is carried out. When the caps are removed, gently knock out the protective cap from the hub and remove it.

After loosen the wheel bolts and the wheel nut. In this case, the machine must stand on the ground. Next, lift the rear of the machine and remove the wheel. Now you can unscrew the hub nut to the end - when installing a new drum, you should also purchase a new nut.

With the coupling pin, the rear brake drum is removed (Logan Dacia is no exception), and with it the bearing. In these cars, the mechanism is a single unit with a hub. In the same way, the second part is removed. If an old drum is to be installed, it is necessary to sew a shoulder on its working surface. It is also necessary to put in operation the mechanism of the gap regulator and to reduce the brake pads with mounting blades.

When installing the rear brake drums "Renault Logan" must be twisted by a mortise nut with a force of 175 Nm. After installation, it is necessary to adjust the clearance, for this several times the brake pedal is squeezed out. In the process, clicks will be heard - when the gap is adjusted, they will stop.

In this way, the drum brake is dismantled for maintenance or replacement. As you can see, you can execute this process yourself, saving money on STO services.