Do-it-yourself brake pad replacement
The principle of operation of automobile brakes is quite simple: under the influence of the braking force transmitted from the brake pedal through a sealed line (on passenger cars, more often hydraulic), the pistons of the brake cylinders move the stationary pads to the rotating discs or drums, due to friction they slow down. At the same time, the pads are made of relatively soft composite materials that are resistant to overheating, but wear out rather quickly.
SHOE SERVICE LIFE
How to change your own brake pads
Unlike many other components of the brake system, brake pads are consumable items, and wear out fairly quickly. The operating instructions for cars recommend checking the wear of the pads (discs, and the general condition of the system) at each MOT, that is, after 10-15 thousand kilometers. The front pads almost always wear out faster than the rear ones - due to the fact that the main load during braking falls on the front axle.
The service life of brake pads depends on several factors:
Driving style. Aggressive, with frequent braking leads to accelerated wear of the pads and discs. In this case, it makes sense to check the pads more often.
Operating conditions. High temperatures, rough, dusty, polluted roads wear pads much faster.
Serviceability of the brake system. In case of acidification of the brake cylinders, calipers and their guides, the pads wear out faster.
pad material
According to the type of friction mixtures, the pads are divided into three types:
organic ("soft", based on graphite);
semi-metallic ("rigid", with a high coefficient of friction at high temperatures);
cermet, combining the properties of the first two types.
Soft pads wear out faster, but do less damage to the discs. It is recommended to use this type of pads for drivers with a smooth braking style, as well as for those who are not averse to changing the pads themselves.
SIGNS OF PAD WEAR
13 KEY SIGNS OF WEAR BRAKE PADS
Although some vehicles are equipped with an electronic brake pad thickness sensor, you cannot rely on it completely. Firstly, often the indicators are not on each wheel, but one per axle. Secondly, the indication may occur due to an open circuit. And finally, the system works correctly only when the brake discs are relatively new. In the case when the 3-4th set of pads is used, and the discs are already thin, incorrect operation is possible.
A mechanical indicator (the so-called “squeaker”) is more adequate, but it can also misinform: the cause of the squeak is overheating or wetting of the pads, dirt and pebbles between them and the discs.
Indirectly, pad wear can be determined by changing the position of the brake pedal and the level of brake fluid in the reservoir - they will go down. Again, the situation may indicate other malfunctions.
The best way to check remaining pad thickness is by visual inspection. But far from all cars it is effective without a pit or a lift, and sometimes even without removing the wheel. On drum brakes, it is impossible to inspect without removing the drum, and on disc brakes, the pads can be hidden both behind the rims and behind the wide brackets of the calipers. In addition, it is easier to see the condition of the outer brake pads, and they wear out more on disc mechanisms, as a rule, internal ones. If inspection of the pads is difficult and involves removing the wheel, just in case, you need to prepare to replace them so as not to do extra work.
REPLACEMENT OF PADS
Replacing the brake pads in Wheel Tire Plus. TRW pads in stock.
Brake mechanisms of cars are of two types: disc and drum. Almost 100% of the front axles of modern cars use discs, they also prevail on the rear axles of cars, budget or commercial versions are equipped with drums.
The process of replacing disc brake pads is quite simple. Of the tools you will need:
"balloon" wrench for wheel nuts;
jack;
pear (syringe);
wide flat screwdriver (or crowbar);
3 types of grease: for pads, guides and anti-stick;
liquid WD-40.
The order of work for the disk mechanism:
Loosen the nuts of the required wheel, raise the car on the jack, placing 2 wheel chocks under the diametrically opposite wheel.
If the pads are changed on the front axle, apply the handbrake. Additionally, if there is no drive on the axle where you change the pads, you can put the manual transmission in gear: 1st or reverse.
Turn the steering wheel in the direction of the wheel to be removed, unscrew the nuts, remove the wheel.
Open the hood and brake fluid reservoir cap.
Use a blower to pump out the brake fluid to a minimum (but do not drain the reservoir completely).
Unscrew the caliper guides (if souring, use WD-40). On some vehicles it is necessary to remove both of them, on others it is enough to loosen the second one to tilt the caliper. It depends on the length of the brake hose.
Important! If possible, do not unscrew the brake hose and do not touch
Leave the bypass fitting - this will avoid the bleeding procedure.
Remove / tilt the caliper, remove the pads. Attention! Never leave the caliper hanging on the hose, fasten it to the suspension elements or tie it to a spring or other knot.
Check the thickness of the pads and brake disc. Find out the minimum value for pads in the manual, for discs you can read on the end of the part.
Check the integrity of the brake cylinder seals, the absence of cracks on the hose and chips on the piston. If there are problems, the parts must be replaced.
Push the piston into the caliper as much as possible using a special puller. Keep in mind that in most cases, on the rear axle, the piston is not pressed in, but screwed in. At the same time, monitor the level of liquid in the tank, pump out if necessary.
Lubricate the rear of the pads prior to installing the anti-squeak plates.
Lubricate the guides and, preferably, the surface of the hub against sticking. In all three cases, use a different lubricant.
Assemble the wheel, be sure to repeat the operation on the other wheel of the axle (blocks are changed together).
Upon completion of the operation on both wheels, after tightening the bolts, check the force on the brake pedal by pressing it repeatedly.
Replacing the pads of the drum system is somewhat more difficult. General procedures (like wheel removal) are the same, but there are differences:
In addition to the wheel, the drum must also be dismantled. To do this, either unscrew the two fixing screws and knock on the drum from behind with a hammer shaft, or screw the bolts into other, reserve holes to squeeze them out.
After removing the drum, remember, or better, take a picture of the position of the pads and springs.
Remove the parking brake lever.
Install the pads and springs in exactly the same order - otherwise the brakes will not work.
Assemble the knot in reverse order.
RECOMMENDATIONS
With all the apparent simplicity, replacing pads can be fraught with "pitfalls".
Main dangers:
souring of threaded connections;
detection of additional faults;
violation of safety regulations when lifting a car and working under it.
If you are not confident in your abilities, do not risk it - even in the best case, the car will be immobilized. Contact the professionals