First of all, we unscrew the brake rotor from the hub and check it for deformation. This can be done by placing it on a flat surface (glass, mirror, etc.) and inspecting it. If the rotor is loose, it should be aligned before adjusting the disc brakes. If the deformation is insignificant, then this operation can be performed when adjusting the brakes.
Unscrew the automatic regulator
Use the hexagonal bolts on the shield to remove the pads from the drum.
Automatic governors keep the brakes in good working order at all times, but if for some reason you need to remove the drum, removing the governor will make it a little easier.
Such manipulations are permissible only for some models (for example, Vauxhall).
Sometimes the brake drum is removed to gain access to the pads and the automatic adjustment mechanism.
Remove the wheels, jack up the vehicle and support with axle stands. Unscrew the hexagonal bolts located on the back of the shield. The bolts rotate towards each other, while the pads are separated from the drum. The system requires minor adjustments.
After re-assembly, use the handbrake and brake pedal to restore the brake function.
Bicycle disc brakes
Disc brakes are designed to brake a bicycle by converting kinetic energy into thermal energy by rubbing the pads against the brake disc. As mentioned earlier, bicycle disc brakes are mechanical and hydraulic. Their principle of operation is the same, but there are slight differences in design.
How to install a new mechanical disc brake
- We attach the brake lever to the handlebar in such a way that it lies in the same plane as your forearm. If necessary, adjust the distance from the handle to the grip, at which, grasping the steering wheel with your whole hand, you could normally reach it with your index finger.
- We install the adapter on the frame and tighten the bolts until fully tightened, alternately tightening each bolt.
- We pass the cable with a jacket in such a way that it coincides with the places of its fixation to the frame.
- We insert the cable into a special slot on the brake handle and refuel the shirt. Please note that when installing a new cable, the tension adjustment on the brake lever must be tightened completely minus 1-1.5 turns.
- The position of adjusting the tension of the cable on the caliper is set in the same way as the brake lever. We pass the cable through the hole on the caliper, put it in the groove of the cable lock and, pulling, clamp the fixing bolt.
- After that, we put the end cap on the end of the cable and squeeze it. This is necessary so that the cable does not fluff.
- Next, we proceed to the adjustment, which is described below.
Seized caliper pistons
In disc brakes with a fixed caliper, the pads are controlled by two cylinders located on the sides of the disc.
Jack up the vehicle on the correct side and try to turn the wheel. If it rotates freely, without gripping, ask the assistant to gently press the brake pedal. The wheel should stop almost at the same time as the pedal is depressed.
If not, remove the wheel and look at the pads. If there is a gap between the pads and the surface of the disc, the piston is most likely jammed.
The stationary piston can also press the pads firmly against the disc.
As a result, the brakes are not applied simultaneously, the wheels rotate with a grip, the gaskets wear out quickly, and the fuel consumption increases.
To determine if there is a problem, press the brake pedal, release it and try to turn the wheel. It should rotate effortlessly. If this is not the case, the piston is frozen in one position.
To solve the problem, you need to disassemble the entire unit and clean it. It would be better to entrust this task to specialists from the service station. Typically, pistons wedge from bad weather, corrosion or wear. In this case, replacement of the caliper assembly is required.
In floating caliper systems, there is one cylinder with two pistons. Each of the pistons, movably connected to each other, acts on its own block.
In this case, there is another cause of the malfunction (excessive or insufficient connection of the component parts of the caliper).
Both pistons sit on the same side of the caliper, the body of which moves slightly to maintain sufficient pressure. Dust and corrosion make this movement difficult.
To fix the problem, clean all moving parts and use a lubricant recommended by the manufacturer.
The sliding type caliper has one cylinder with two pistons. One piston belongs to one pad, while the others work with the second pad through a splined connection.
Many riders, first encountering hydraulic or mechanical disc brakes on a bicycle, do not know how to properly set up, adjust or replace consumables. Many consider their design to be much more complex than V-brakes. but it is not so. Technologically, good bicycle disc brakes, especially if they are hydraulic, are more advanced than v-breaks and perform significantly better at their tasks, but remember that this is not the case for cheap mechanics. Next, we will look at how to properly install and adjust disc brakes yourself at home. But we will start with the design features and differences between disc mechanics and hydraulics. And then we will touch on all of the above points.
We set the levers symmetrically
In order for the left and right pads to wear evenly, they must be at the same distance from the rim. Adjustable by spring tension on the brake levers. To equalize the force that returns the left and right brake levers to their original position, use the adjusting bolts located at the base of the levers.
By twisting the bolt clockwise, we tighten the spring, unscrewing it. we loosen it. By pressing and releasing the brake, we check the uniformity of the removal of the pads from the rim. Tighten the bolts on the left and right sides until the pads move the same distance when the brake lever is released.
How to adjust hydraulic disc brakes (bicycles)
The adjuster pin that goes through the brake shield pivots the helical cam towards the brake pad pin.
There are wedge and cam adjusters. Often the end of the adjuster is a square or hexagonal rod that goes through the brake shield.
These rods are usually recessed so they cannot be adjusted with a double-sided wrench. Always use the correct type of car key to avoid damaging the regulator.
Remove the plug in the shield to see the regulator.
If for this you need to remove the wheel from the axle, loosen the fastening nuts before lifting the car on the jack and support the wheel with an axle support.
Remove the shield plug on the desired side and turn the ratchet with the tip of a large flat-blade screwdriver.
Use a large screwdriver to turn the ratchet.
Check the direction of the turn in your car manual. If there is no manual, turn the ratchet to any direction a few teeth. This should be enough for the brake pad to move closer to the drum and no longer move. If the shoe is not in contact with the drum, turn the ratchet the other way one or two clicks, or until it rotates freely.
Adjusting and adjusting the brakes on a bicycle yourself. disassemble carefully
Normally, the disc brake stops the wheel as quickly as possible, allowing the force to be dosed on the verge of locking the rotor. Deviations appear after replacing the cable, pads and overhaul. However, the settings are violated during long-term use, as well as after removing the wheel, for example, to seal the bicycle camera at home. How to avoid the famous shuffling of the rotor, how to eliminate the braking, and, in the end, how to restore the factory braking character. these and other questions are answered by the editorial staff of Autobann magazine.
How to check and adjust the brakes
There are clear instructions for checking and adjusting the brake system of a bicycle. If you stick to it, then the whole process will take little time and will be effective.
Procedure for checking and adjusting the brake system of a bicycle:
- Dry brake test. It is necessary to raise the front wheel and, having unwound it, press the left brake lever. If the wheel comes to a sudden stop during this test, the braking system is in order and no maintenance is required. Honor has one caveat. if the brake lever touches the steering wheel, then you just need to pull the cable. The operability of the rear wheel brake system is checked in the same manner. To tighten the cable, you need to use curly bolts. just tighten them a little and, if only minor adjustments are required, this will correct the situation. It often happens that such a minimum adjustment does not work. in this case, we look where the end of the cable is on the bike (it is always longer than necessary in advance), unscrew the bolt that holds it. It remains only to tighten part of the cable with pliers and tighten the bolt, applying the possible force.
- Checking the brake pads. After the brake levers have been tested, the condition of the brake pads should be carefully examined. However, the order of action can be changed. first work with the pads, and then with the handles.
The setting of the brake system for rim and disc type is different, since different rotating mechanisms and pads are used.
Checking the condition of the brakes
First of all, we “unfasten” the brake, as shown in the photo.
Check how the cable (G) moves in the shirt (A) by pressing and releasing the brake lever and pulling the cable back with your finger. the movement should be free, without delay. If the cable pulls hard, it may be damaged, the shirt or cable guide (C), or dirt has accumulated inside the jacket or cable guide. They must be removed and cleaned or replaced.
Check the condition of the pads (J). They should show dirt drainage grooves (the block should not be smooth). Worn pads without grooves must be replaced. Check that the pads are complete with washers and that they are correctly installed.
Observe the order of the washers when installing new pads.
The brake levers (I) must swing freely in their seats and spring apart after being compressed. If the movement is difficult, the brake during operation may get stuck in the closed position and rub the pad on the rim. In this case, you can remove the levers from the seats, clean and lubricate the contact points and reinstall.
When installing, make sure that the protruding pin on the arm fits into the hole in the frame, and that the hole on the left and right arm is the same.
Adjust the position of the brake lever and the tension of the cable
To bring the brake lever closer to the steering wheel (for example, so that you do not have to reach for it with your fingers), tighten the bolt on the brake lever.
In this case, keep in mind that you should not bring the handle too close to the steering wheel. It should not touch the grip when fully clamped.
How To Set Up And Adjust Your Brakes | Mountain Bike Maintenance
When the position of the brake lever is set, it remains to adjust the tension of the cable. The task is to bring the pads as close to the rim as possible, leaving a distance of 2-3 millimeters between the pad and the rim.
To do this, you can tighten the cable in two ways:
- For a rough adjustment, if the cable is very weakly tensioned, and the pads are far from the rim: loosen the bolt fixing the cable in the brake lever, tighten the cable, tighten the bolt.
While loosening the bolt, hold the lever and the cable so that the cable does not “run away” and you do not have to re-thread it into the seat.
- for fine tuning, we use the adjusting screw at the point where the shirt comes out with a cable from the brake lever.
To make the screw spin freely, loosen the lock nut by unscrewing it counterclockwise. Turning the screw clockwise, we loosen the cable tension (the pads move away from the rim), unscrewing it counterclockwise, we increase the tension (the pads are closer to the rim). When the pads are in the right position, tighten the lock nut.
That’s all! Checking how everything works. If necessary, readjust the springs of the levers (item 3).
Setting up disc brakes
As a rule, adjustment of disc brakes consists in periodically tightening the cable. But often you have to replace the pads, however, on disc brakes they wear out longer than on rim brakes. First you need to find out which specific disc brakes are installed on the bike. brake pad adjustments for hydraulic and mechanical systems will differ.
Experts recommend taking note of the following points:
- If there are hydraulic disc brakes on the bike, then replacing the pads may not be necessary. they are able to do it on their own. But there is one caveat to Honor. if the hydraulic system is closed, then you will have to adjust the pads in manual mode. for this, special valves are provided.
- If you have to adjust disc mechanical brakes, then you will need to pull the cable according to the above instructions and check the location of the pads. the distance between them and the disc should be within 0.2-0.4 mm.
- In order to adjust the pads with disc mechanical brakes, you need to use special bolts. by tightening them, you can see how the pad moves. You need to be especially careful when setting the distance between the pad and the disc. 0.3 mm is too small, it is easy to make a mistake.
After carrying out the work, be sure to check the operation of the brake system in action. ride your bike for a few meters and try to brake. If the cable is too tight, or the pads are too close to the disc, then too sharp braking will occur. this is a “surprise” in which the cyclist starts to move forward, but without his own vehicle. Therefore, when driving for a test, you need to be extremely careful and careful, if necessary, the disc brake system is adjusted again taking into account previous errors.
Before adjusting: preparing for tuning
The decision to adjust disc brakes on a mountain bike or road bike will only be successful if the brake system is diagnosed. By the way, the diagnostic measures for hydraulics and mechanics will be different. We have already talked about how hydraulic brakes on a bicycle differ from mechanical ones.
In short, in the hydraulic circuit, both pads push the fluid, acting on the caliper pistons, which results in clear modulation and easy handle travel. And in mechanics, only one friction lining is movable. It is brought to the disc by pulling the cable with the brake lever.
However, whatever the brake drive is, it is worth checking:
- Rotor for deformation. For 100% confidence in the flatness of the disc, it is better to unscrew it and put it on a flat surface. A rough estimate can be made while on the bike by spinning the wheel and estimating the distance to both pads through the slot in the caliper. Friction linings must be equidistant from the disc in any position.
- Brake pad wear and integrity. Remove the pads by removing the cotter pin and assess the residual thickness of the friction material. The surface in contact with the disc must be free of pits and dents.
- Cleanliness of pads and rotor. The presence of oil traces and accumulations of dirt on their working surfaces is not allowed. To clean them, you can use fine sandpaper (for example, “zero”) and rags soaked in any cleaner (acetone, ammonia.).
- Wheel hub location in frame / fork dropouts. The bushing should fit freely into the seat and abut against the mating surface of the frame or fork. Distortions in the installation cannot be avoided, but they should be minimal, practically invisible. Micron skewing is immediately audible on the brakes in the form of rotor shuffling. This is why disc brake re-adjustment is required after re-mounting the wheel.
It will not be superfluous to take a look at the state of the drive. With cable disc brakes, check the cable integrity. The end should not be unwoven, and the service life should not exceed 3 years. When replacing the cable, change the shirts. It is not necessary to lubricate it, but if you decide, then do it only with a special lubricant that does not attract dust.
The hydraulics should not leak. Weaknesses are connections:
- Master cylinder. hydraulic line.
- Brake Lever. Master Cylinder.
- Brake caliper.M
Adjusting the rim brakes
Mountain bikes use a v-brake braking system. by its example, we will consider the principles of tuning, as it is also available on other bicycles with rim brakes. The difference can only consist in a different arrangement of bolts and screws that will need to be tightened / tightened.
Note: it is important to observe three main rules:
- the pads should be parallel to the rim;
- the gap between the rim and the block should not be more or less than 1 mm;
- the pads should be symmetrical with respect to each other.
How to achieve these guidelines when adjusting rim brakes on a bicycle:
- You need to find a hex nut. it fixes the pads. To loosen it and set the brake pads in the desired position, you need to press the brake lever and watch how the shoe touches the rim. By releasing the brake lever, the shoe can be set to the desired position. it moves up, down and at an angle.
- The distance between the block and the rim of the wheel should not be more than 1 mm, although in some models of bicycles there are also 2-3 mm. exact information about a specific vehicle can be obtained either from the instructions for it, or on the Internet for technical characteristics. It follows from Honor that the wheel should be braked even with the smallest pressure on the brake lever. That is, if the wheel stops only when the brake lever is fully pressed “all the way”, then this is incorrect.
After carrying out all the specified work, it is imperative to check the operation of the brake system. First, this is done at idle speed. lift the front wheel up, spin it and press the handle sharply, then do the same with the rear wheel. The next step is to check the operation of the brake system “in action”. get on the bike and ride 3-5 meters, braking sharply. If the bike stops even when the brake lever is pressed slightly, then the system has been serviced correctly.