Do-it-yourself brake pad replacement
Content
- How a car's braking system works
- Why change brake pads?
- When to change brake pads?
- How to determine the degree of brake pad wear?
- Preparing your car for replacing brake pads
- Brake pad replacement tools
- Types of car brake pads
- Replacing the front brake pads (disc brakes)
- Replacing rear brake pads (drum brakes)
- Front and rear pad wear signs
- Signal from the wear sensor
- Brake fluid level
- Increasing the brake pedal travel
- Mechanical damage
- Uneven pad wear
- Increased stopping distance
- Violation of straightness during braking
- The appearance of a beating of the wheels when braking
- The appearance of a creak and rattle
- The appearance of a dark coating or dust on the rims
- What causes untimely pad replacement?
- How often do brake pads change?
- What factors can affect pad wear?
- How to reduce brake pad wear
- What to look for when buying
- Do I need to change the brake fluid after every pad change?
- Related videos
- Questions and answers:
The brakes in the car belong to the active safety system. While the vehicle is moving, the driver often activates it, sometimes doing it at the subconscious level. How often the brake pads will wear out depends on the driver's habits and the operating conditions of the car.
In this review, we will consider the reasons for the failure of the car brakes, how to change the brake pads on your own, and also what can be done so that they do not wear out so quickly.
How a car's braking system works
Before discussing the process of replacing elements of a car's braking system, it is necessary to consider how it works. Most mid-range and budget models are equipped with disc brakes at the front and drum brakes at the rear. While the goal is to slow the car down - the two types of brakes work slightly differently.
In disc brakes, the main mechanism that slows down the wheels is the caliper. Its design, modifications and principle of operation are described here... The brake pads, which are in its design, clamp the brake disc on both sides.
The drum modification is made in the form of a drum mounted on the rear wheel hubs. The brake pads are located inside the structure. When the driver presses the pedal, the pads spread out to the sides, resting against the drum rims.
The brake line is filled with a special fluid. The principle of expansion of liquid substances is used to activate all elements. The brake pedal is connected to a vacuum that increases fluid pressure in the system.
Why change brake pads?
The quality of the brake pads directly affects the vehicle's deceleration efficiency. This process is especially important in emergency situations, for example, when a child runs out onto the road or another car suddenly appears.
The friction lining has a certain thickness. The more often and harder the driver applies the brakes, the faster they will wear off. As the friction layer becomes smaller, the driver needs to exert more effort each time to slow the car down.
The car's braking system works in such a way that the front pads wear out more than the rear ones. If you do not change them in time, this will lead to loss of vehicle control at the most inopportune moment. This in many cases leads to an accident.
When to change brake pads?
The car manufacturer indicates this regulation in the technical documentation. If the car was purchased on the secondary market, then, most likely, these securities are no longer available. In this case, the official data about the car, published on the Internet on the websites of manufacturers or dealers, will help.
Since the pads wear out depending on how actively they are used while driving, the replacement of brake pads is not determined by the time interval, but by the state of the friction surface. Most pads need to be replaced when this layer becomes two millimeters thick.
Operating conditions also affect the suitability of the pads. For example, in a car that often travels on the highway, the braking system is used less than in the same car, only in an active city mode. And if we compare the pads of these cars with SUVs that often conquer swampy areas, then in the second case, due to the presence of abrasive particles, the friction surface wears out faster.
In order to notice the wear of the pads in time, during the seasonal replacement of rubber, attention should be paid to the brake pads, as well as the condition of the discs and drums.
Watch a short video on how to eliminate squeaky brake pads:
How to determine the degree of brake pad wear?
The wear of consumables of the brake system, and discs and pads are just consumables, because the brakes require dry friction between these elements, can be determined visually. In most modern brake systems, a special metal plate is provided, which, if the friction layer of the brake pad is heavily worn, will scratch the brake disc, while making a strong creak.
Some types of brake pads are equipped with wear sensors. When the block is worn out (the residual thickness is one or two millimeters), the sensor transmits a signal to the control unit, due to which the corresponding icon lights up on the dashboard.
To prevent pad wear from taking the driver by surprise during a long trip, experts recommend checking the thickness of the pads every 10 thousand kilometers, especially if the driver likes a sporty driving style with frequent braking.
As for the wear of the brake disc, this can be determined by touch by swiping your finger over the contact area of the edge of the brake pad. If a deep edge has formed on the disc, then it must be replaced. Given that the disc is an expensive part of the brake system, before replacing it with a new one, you should measure the wear depth. If the edge is more than 10 millimeters high, then the disc definitely needs to be replaced.
Preparing your car for replacing brake pads
It does not always take a lot of time and effort to repair the brake system. To get your car ready for replacing the pads, you need to take care of safety first. To do this, first you need to make sure that the machine does not move during the work. Chocks will help with this.
The wheel on which the pads will be replaced is loosened (the bolts do not completely loosen). Next, the car is jacked up and the bolts are unscrewed to remove the wheel. To prevent the car body from sliding off the jack and not damaging important elements when falling, it is important to prevent this situation. To do this, a safety wooden bar is placed under the suspended part.
Some put the removed wheel, but in the process of replacing the pads, it will interfere. In addition, the car owner will be partially under the car when performing work, and in an emergency situation, the width of the rim may not save from injury when the car falls from the jack.
In addition to a wheel wrench, wheel chocks and a safety bar, you will need other tools to service the brake system.
Brake pad replacement tools
To replace the pads you will need:
- Clamp. It comes in handy in order to put pressure on the piston of the disc brake caliper. This will facilitate the subsequent assembly of the mechanism in its place. Also, when the device is disconnected from the line (if a decision is made to replace the brake fluid at the same time), there is the remainder of the fluid in its reservoir, which also needs to be drained into the container;
- Open-end wrench suitable for the section of the caliper mounting bolts and the brake line union;
- Personal protective equipment. These are gloves, respirator and goggles. They are needed because the brake fluid contains substances harmful and aggressive to the skin. Hands, eyes, and especially the respiratory tract must be protected from them. During the dismantling of boiled metal parts, chips are often chipped, which can get into the eyes. For this reason, goggles are especially needed;
- Although not a tool, but a consumable, new brake pads should also be prepared in advance.
Most motorists have a good habit of having the necessary tools in their garage or even carrying in their car. This will make it easier to prepare the car for replacing the brake pads.
Types of car brake pads
All brake pads are divided into two types:
- For disc brakes;
- For drum brakes.
They differ from each other in shape, but they work in the same way - they rub against the smooth surface of a steel disk or drum.
According to the material of the friction layer, brake pads are divided into the following types:
- Low metal. The composition of the friction layer of such pads contains 10-30 percent of the metal (copper or steel is used). The rest of the binding materials are organic. When using such pads, the brakes are very noisy, and due to the large amount of organic substances, they create a large amount of dust that settles on the discs.
- Semi-metallic. Such products consist of metal from 30 to 65 percent, and the binders are organic and graphite. These pads also create noise when braking, but compared to the previous type, they last longer.
- Ceramic. This product is the most expensive, but at the same time less noisy, does not wear out the brake discs so much and has an increased resource. As part of such pads, ceramic fibers contain an admixture of non-ferrous metals.
- Asbestos-free or organic. The composition of such pads can be different, for example, Kevlar, glass, carbon, and rubber, various resins and rubber are used to bind the fibers. Brakes equipped with such pads are the softest and most gentle on the discs. But because of the great softness, they wear out quickly and form a large layer of dust.
Video: Which brake pads are better to put on AUTO
Here is a short video review of brake pads for a car:
Replacing the front brake pads (disc brakes)
Here is the sequence in which the front brake pads are replaced:
- Under the hood, the cover of the master brake cylinder expander is unscrewed - this way it will be easier to press the piston into the seat;
- The steering wheel is turned out so that there is free access to the brake caliper fasteners;
- The caliper guides are removed. In order not to drain the fluid from the system and not damage the hoses during repair, it is worth using a wire to fix the caliper to the shock absorber so that it does not hang on the hose;
- The clamp pushes the piston into the seat;
- Use a flat screwdriver to remove old pads and anti-squeak plates;
- Plates and brackets are lubricated with grease so that they do not wear out during the operation of the system;
- Before installation, the caliper body must be cleaned of dirt;
- Grease is applied at the places where the brake pads are mounted;
- Pads are installed in accordance with the manufacturer's manual;
- If there are residues of grease, they must be removed with a rag;
- The piston can also be lubricated;
- The caliper is installed in place (you need to be careful so that the guides are not damaged);
- Lubricant is also applied to the caliper guides and then clamped.
The same procedure is carried out on the second wheel. As soon as the work is completed, you need to close the cover of the GTZ tank. Finally, the tightness of the system is checked. To do this, press the brake pedal several times. If there are no fluid leaks, then it was possible to complete the work without damaging the line.
Replacing rear brake pads (drum brakes)
Replacing the rear brake pads is done in a slightly different way. The machine must first be prepared in the same way as when working on the front end. The vehicle is removed from the parking brake, as it activates the rear pads.
Then, given that the rear pads are inside the drum, the entire assembly must be removed. Next, the pads change in the following sequence:
- The drum mounting bolts are unscrewed;
- Often the drum is removed with some effort. In this case, you can tap on it a little with a hammer, while simultaneously removing it from the hub;
- The rear brake mechanism consists of many springs, rods and latches, so it would be better to photograph the location of each;
- The parking brake cable is disconnected;
- To remove the old pads, you will have to completely disassemble the assembly;
- A new pair of pads is installed according to the photograph taken in advance;
- The parking brake cable is connected and the drum is installed back.
As with the front brakes, you need to check the system by depressing the brake pedal several times.
If in the process of replacing the pads it will also be necessary to change the brake fluid, then a separate article tellshow to do it right.
Front and rear pad wear signs
The braking system consists of many components in which damage can occur. The main malfunction is brake pad wear. Here are some signs that may indicate other breakdowns in the system.
Signal from the wear sensor
Some modern cars have a pad wear sensor in the brake system. There are two types of driver wear alerts:
- There is a signal layer on the block itself. When the friction part is used up, the signal layer begins to emit a characteristic sound (squeaks) during braking;
- Electronic sensor. When the block is worn to the appropriate extent, a signal appears on the dashboard.
Brake fluid level
When the brake pads wear out, more hydraulic fluid is required to effectively decelerate the vehicle. This is because the caliper piston has a longer stroke. Since the wear of the friction part is almost imperceptible, the liquid level in the expansion tank will also drop slowly.
Increasing the brake pedal travel
The situation is similar with the brake pedal travel. The thinner the friction layer, the greater the pedal travel. This feature also does not change dramatically. However, by increasing the driver's efforts during braking, it can be determined that the braking system needs the attention of a master.
Mechanical damage
If you notice chips or other damage to the brake pads, they must be urgently replaced. In addition to replacement, it is necessary to find out why this situation occurred. This can be due to poor quality parts or damage to the brake disc.
Uneven pad wear
If it was noticed on one of the wheels that the pad was worn out more than on the others, then in addition to replacing it, it is necessary to repair or replace the brake caliper. Otherwise, the brakes will not apply evenly, and this will negatively affect the safety of the vehicle.
Increased stopping distance
The pads also need to be replaced when the braking distance of the car has noticeably increased. An especially alarming signal is when this indicator has changed dramatically. This indicates either faulty calipers or excessive pad wear. It will also not hurt to check the condition of the fluid - its amount and the need for a scheduled replacement.
Violation of straightness during braking
If the car pulls to the side when you press the brake, this may indicate uneven wear on the pads on different wheels. This happens when the calipers or the brake line do not work correctly (a malfunction of the brake cylinders).
The appearance of a beating of the wheels when braking
If during braking, the beating of the wheels (or one wheel) is clearly felt, then this indicates the destruction of the brake pad. For example, due to a factory defect or an expired service life, the friction layer cracked and began to spill out.
If the caliper rumbles when the car is moving, then the reason for this may be a strong pad wear. In a fairly worn block, braking will be carried out due to the metal base. This will certainly lead to damage to the brake disc, and in some cases to a sharp blocking of the wheel during braking.
The appearance of a creak and rattle
Most modern brake pads have a large amount of metal chips in the friction layer at the minimum wear level. When the pad wears down to this layer, metal chips scratch the brake disc, causing a loud squeak or squeak when braking. When this sound occurs, the pads must be replaced so that they do not scratch the discs.
The appearance of a dark coating or dust on the rims
This effect is natural for most types of budget segment brake pads. Graphite dust occurs due to the wear of the friction layer, which partly consists of various kinds of resins and graphite, which sinter during braking and form soot dust that settles on the rims of the car. If metal shavings are clearly visible in the graphite dust (characteristic “mettalic” ebb), this indicates wear on the brake disc. It is better to replace the pads with a better analogue.
What causes untimely pad replacement?
First of all, worn brake pads will squeak a lot when braking. But even if the driver has iron nerves, and he is not bothered by extraneous noise, untimely replacement of the pads can lead to serious damage.
Here are the consequences of not following the brake pad replacement schedule:
- Strong creaking sound;
- Premature wear of brake discs;
- Brake calipers will fail faster because brake pads will push the caliper piston out more when the brake pads are worn. Because of this, it can warp and jam, which will lead to the braking of one wheel even with the pedal released;
- Critical wear of the brake disc can lead to a wedge of the pad on the burr of the disc. At best, the brake system assembly will shatter. In the worst case, a locked wheel can cause a serious accident, especially if the car was moving at high speed.
How often do brake pads change?
Since brake pad wear is influenced by a large number of various factors, from the material from which they are made to driving style, it is impossible to establish an exact interval for replacing these consumables. For one motorist, they do not leave even 10 thousand, while the other will ride more than 40 thousand on the same pads.
If we take the average figures, then with materials of low or medium quality, the front pads will need to be changed after about 10 thousand kilometers, and the rear pads after 25.
When installing better materials, it will be necessary to change the pads at the front after about 15 km, and at the rear after about 000 km.
If a combined brake system is installed in the car (discs in front and drums in the back), then the pads in the drums wear out more slowly, and they can be changed after 80-100 thousand.
What factors can affect pad wear?
Given that brake pads are a consumable item, they must be changed depending on the degree of wear or after a certain mileage. It is impossible to create a strict rule at what interval to change this consumable, because many factors influence this. That's what affects the schedule for replacing pads.
Car model and make
Subcompact, SUV, premium car or sports car. The braking system of each type of vehicle works with different efficiency. In addition, cars have different dimensions and weight, which also affects the wear of the pads during braking.
Conditions in which the vehicle is operated
Since all kinds of dirt on the road gets on the pads while driving, foreign particles will certainly cause premature wear of the pads.
Driving style
If the driver often uses a sporty driving style (fast driving over short distances with frequent braking), then the friction material of the pads will wear out many times faster. To prolong the life of your brakes, slow down your vehicle earlier and avoid using emergency braking. You can slow down the car, for example, using the engine brake (release the gas pedal and switch to a lower gear at the appropriate engine speed).
The quality of the material used in the manufacture of the pad
This factor plays a key role in pad life. Manufacturers of such consumables use different materials that provide maximum grip on the brake disc or drum. Each of these materials has its own resistance to mechanical and thermal overloads.
How to reduce brake pad wear
Regardless of the motorist's driving style, the brake pads will still wear out and need to be replaced. This is influenced by the following factors:
- Car operating conditions - poor road surface, frequent driving through mud and sand;
- Driving style;
- The quality of replacement parts.
Despite these factors, the driver can extend the life of the brake pads. Here's what he can do for this:
- Brake smoothly, and for this you should keep a safe distance;
- During the braking distance, do not hold the pedal, but perform several presses;
- To slow the car down, use the engine braking method in conjunction with the brakes;
- The brake pads of some cars freeze if you leave the car with the handbrake raised for a long time in the cold.
These are simple actions that any driver can perform. Safety on the road depends on the effectiveness of the braking system, so proper attention should be paid to its serviceability.
What to look for when buying
Each driver must proceed from the individual characteristics of the car and the conditions in which it is operated. If in a particular case, budget pads take care of a lot, then you can purchase them. Otherwise, it would be better to choose a better option. First of all, it is necessary to focus not on what other drivers recommend, but on the condition of the pads during periodic diagnostics.
Do I need to change the brake fluid after every pad change?
Although the performance of the system depends on the brake fluid, it is not directly related to the pads or brake discs. Even if you put new pads with discs without changing the brake fluid, this will not affect the entire system in any way. An exception is the need to replace the fluid, for example, when the time has come for this.
Related videos
In addition, we offer a small video test of different brake pads:
Questions and answers:
How long does it take to replace the brake pads? It depends on the operating conditions, vehicle weight, engine power and driving style. In urban mode, they are usually enough for 20-40 thousand kilometers.
When do you need to change the brake discs? The life of the discs is much longer than the pads. The main thing is to prevent complete wear of the pads so that they do not scratch the disc. On average, the disks change after 80 thousand km.
How do you know when you need to replace the brake pads? Squeaking or rubbing sound of metal during braking. The brake pedal goes down. During stopping, vibration is generated, there is a lot of soot on the rims.