Part 1. Preparation and safety
Objective
- Check and adjust brake fluid level.
Safety check
- Never use any petroleum or mineral based products, such as gasoline, kerosene etc, to clean a braking system or its components. They are not compatible and will result in a failure of the braking system and its components. This may result in injury to the passengers or damage to the vehicle.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Brake fluid can damage the paintwork by softening the base paint.
- Brake fluid has a hygroscopic nature; it will absorb moisture rapidly. Always replace the cover or lid as soon as possible.
- The higher the D.O.T. number of the brake fluid, the higher its boiling point.
- Do not mix any D.O.T. 5 silicone-based brake fluid with a D.O.T. 3 or 4 glycol-based fluid because they are incompatible.
- As glycol-based brake fluid absorbs moisture its boiling point is lowered. This can cause the phenomenon known as 'brake fade'.
- Brake fluid is stored in the master cylinder. If you are unsure of its location, consult the vehicle's shop manual or the owner's manual.
- If your vehicle has antilock brakes, consult the owner's manual before filling the cylinder.
- If brake fluid splashes into your eyes, rinse it out with tap water immediately.
- Do not swallow brake fluid. It is toxic.
- Brake fluid reservoirs will indicate the maximum and minimum levels with a marker on the side or level bars inside the container.
Part 2: Step-by-step instruction
- Check brake fluid
Wipe around the master cylinder top cover to prevent any dirt from entering the system. Open the top of the master cylinder, by removing the plastic lid, or by prying the retaining clamp from a metal cover. Look inside the master cylinder. The fluid should be up to the “FULL” line on the side of the cylinder or within half an inch of the top of each chamber.
- Adjust brake fluid
Add the manufacturer’s recommended brake fluid only if needed. Replace the cover and check that it is fully seated.
- Final inspection
Check for any leaks around the master cylinder with a flashlight. Dilute any brake fluid that may have been spilt with fresh clean water. Do not rub the fluid with a cloth.
Part 1. Preparation and safety
Objective
- Test and replace brake fluid in accordance with manufacturer's recommendations.
Safety check
- Never use any petroleum or mineral based products, such as gasoline, kerosene etc, to clean a braking system or its components. They are not compatible and will result in a failure of the braking system and its components. This may result in injury to the passengers or damage to the vehicle.
- If brake fluid splashes into your eyes, rinse it out with tap water immediately.
- Do not swallow brake fluid. It is toxic.
- Make sure that when you are bleeding the brakes, you do not empty the brake fluid reservoir or you will cause internal damage to the master cylinder.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Brake fluid can damage the paintwork by softening the base paint.
- Brake fluid has a hygroscopic nature; it will absorb moisture rapidly.
- As moisture is absorbed, the boiling point is lowered. This can cause the phenomenon known as 'brake fade'.
- Always replace the reservoir cover or lid as soon as possible.
- Do not use brake fluid that has been left in an open container.
- Brake fluid types are identified by their D.O.T. number. The higher the D.O.T. number, the higher its boiling point.
- Most vehicles use either D.O.T. 3 or D.O.T. 4 fluid. These fluids are both glycol-based but differ in specifications. The reservoir cover or cap will usually state the type of fluid to be used.
- A D.O.T. 5 is synthetic fluid and normally referred to as 'silicone' brake fluid; it's usually colored purple for easy identification and it's not recommended for vehicles fitted with ABS.
- Do not mix D.O.T. 5 brake fluid with a D.O.T. 3 or 4 glycol-based fluid. They are incompatible.
- The majority of today's braking systems use a combination of dissimilar metals. Manufacturers use aluminum in pistons and housings, steel in some wheel cylinders and brake lines.
- When moisture mixes with brake fluid a galvanic action can occur. Galvanic action is similar to the operation of a battery. The more moisture in brake fluid, the higher the galvanic reading and the greater the corrosion it causes.
- If you need to bleed your brakes, you may need to replace your brake fluid.
- When bleeding the brakes, it will be necessary to top up the brake fluid after bleeding each brake station.
- Most manufacturers recommend that brake fluid be changed at least every two years. Consult your owner's manual for the specified intervals for the model you are working on and the type of replacement brake fluid recommended.
- There are a number of different brake bleeding methods. Some repair shops will use a 'pressure bleeder' while others may have a 'vacuum brake bleeder'. Manual bleeding is discussed in this procedure.
- Manufacturers recommend that when bleeding brakes; push the brake pedal to the floor. If you are changing brake fluid on an older vehicle, or if you are uncertain of the vehicle's service history, it is wise to depress the pedal through its normal range of movement. This will prevent the components in the master cylinder from coming into contact with contaminants.
- Brake assemblies, either disc or drum, are often referred to as braking stations.
Part 2: Step-by-step instruction
- Check for galvanic reaction
Remove the brake fluid reservoir cap, and set the DVOM to read voltage on the lowest voltage range of the meter. Place one of the DVOM probes into the brake fluid, and the other against the body of the master cylinder. The voltage should be no greater than 0.3 volts. If the voltage is higher, this indicates a galvanic reaction, and means that there is an unacceptable level of moisture in the brake fluid.
- Remove the excess brake fluid
Use an old hydrometer or similar device to suck out the contaminated fluid from the master cylinder reservoir. Place the discarded brake fluid into a container that can be disposed of in an environmentally friendly manner.
- Top up with new fluid
Top up the master cylinder reservoir with clean fluid until it reaches the “FULL” line. Close the brake fluid container as quickly as possible to prevent contamination and evaporation of the fluid.
- Manually bleed the brake system
Open the bleeder screw that is the furthest from the master cylinder and ask an assistant to slowly push the brake pedal down. With a clear bleeder hose inserted into a jar, you can observe the air bubbles coming out. Close the bleeder screw off, and have the assistant slowly release the pedal. Continue this process until there are no more air bubbles coming out of the brake station and the new brake fluid is present. Close off the bleeder screw and tighten it to the manufacturers specifications. Repeat this procedure for each of the other brake stations, moving closer to the master cylinder.
- Inspect and test
Have your supervisor inspect each of the brake stations to ensure that there are no leaks and the bleeder screws are closed correctly. A simple way of doing this is to ask the assistant in the vehicle to place their foot on the brake pedal, as if they were applying the brakes when driving the vehicle normally. Now you can check all the bleed points and hose connections for leaks while the assistant is maintaining the pressure on the system, and thus any fluid that could be leaking as a result of a loose joint in the components. After your supervisor is satisfied that it is all correct, lower the vehicle. Carry out a final check for any leaks around the master cylinder or brake stations. Replace the master cylinder cover and check to see that it is fully seated. Dilute any brake fluid that may have been spilt with fresh clean water. Ask your supervisor to check the brake system pedal pressure, fluid levels, and visual signs of leaks. When the supervisor is satisfied, the vehicle should be road tested by a qualified person to ensure the integrity of the braking system.
Part 1. Preparation and safety
Objective
- Check brake pads and calipers. Check and measure rotors.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Most vehicles have four-wheel disc brakes.
- You should check the disc brakes and disc brake linings every 15,000 kilometers (10,000 miles).
- After checking the brake pads, replace the road wheel but don't put lug nuts into the socket of the impact wrench and power the lug nuts on; this practice can lead to the wheel nuts going on cross-threaded.
- When inspecting the caliper be very careful because the caliper may be hot if the car has been driven recently.
Part 2: Step-by-step instruction
- Check brake caliper
Make sure the caliper is cool to the touch, then grasp it and try to move it to make sure it’s mounted securely.
- Check brake pads
Look through the dust shield on the caliper and look at the brake pads. Check the linings on the brake pads. If they are too worn, they may have to be replaced. The easiest way to estimate the wear is to look at the thickness of the backing plate of the pad, and, if the thickness of the remaining brake lining surface of the pad is the same or less than that of the thickness of the backing plate, the pads should be replaced. If the linings have worn so much that they are running on the pads backing plates, have your supervisor inspect the system, as the disc may have to be reground.
- Check and measure the rotor
Check the visible part of the rotor for rust, scoring, and uneven wear. Check the shop manual for the specifications of this rotor and measure its thickness with an outside micrometer. If the reading is outside the manufacturers specification, report it to your supervisor. Repeat these procedures for the other three wheels.
Part 1. Preparation and safety
Objective
- Replace brake pads and refit according to the manufacturer's recommended procedure.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Before you raise the vehicle, you will need to remove some of the brake fluid from the master cylinder. Using a siphon, remove enough fluid to cause the reservoir level to drop well below the fill mark. This allows the fluid in the lines to return to the reservoir without overflowing when you retract the caliper pistons for the new pads.
- During inspection, the flexible brake hose will need to be supported because it is still attached to the caliper. The easiest way to do this is by fastening a length of wire around the caliper and attaching it to a suspension component.
- Do not let the caliper hang unsupported because you may damage the flexible brake hose.
Part 2: Step-by-step instruction
- Remove brake fluid
Before you raise the vehicle, you will need to remove some of the brake fluid from the master cylinder to allow for fluid return into the master cylinder reservoir when you install the new brake pads. Using a siphon, remove enough fluid so that the reservoir level is well below the fill mark.
- Raise the vehicle and remove wheel assembly
Raise the vehicle to a comfortable working height. Remove the wheel assembly.
- Inspect the brake assembly
Check for any signs of fluid leaks or grease leakage from the hub seal. Check for any signs of a cracked or damaged rotor. Inspect the brake lines to see if there are any signs of leakage or deterioration of the flexible hoses.
- Remove the brake pads
Loosen and remove the caliper location pins or bolts. Lift and rotate the caliper away from the rotor. Ensure that the caliper is not hanging unsupported. Secure and support the caliper by fastening a length of wire around it and attaching it to a suspension component. Remove the worn brake pads from the caliper by pulling them from their guide locations. It is good practice to lightly skim the rotors when new pads are to be installed, so arrange with your supervisor to have the rotor machined. Carry out a run out test with a dial gauge in addition to measuring rotor thickness with an outside micrometer. This will determine the amount of material to be skimmed. Mount the dial gauge fixture to a fixed point in relation to the rotor, so that when the rotor is turned it shows how much run out variation there is in the disc. Check the amount of run-out against the manufacturers specifications and report any excessive tolerances in your findings to your supervisor .
- Check the slide or locating pins
Check the locator pins, sleeves, and insulators for any signs of wear or binding. With the sliding caliper type, ensure the caliper can slide freely on the runners.
- Retract the piston
To fit new pads, you will need to retract the caliper piston back into its housing. One of the most common methods is to fit a block of wood and a ‘C’ or ‘G’ clamp over the piston. Tighten the clamp to retract the piston back into the housing. As the piston moves back, it will displace brake fluid back into the master cylinder reservoir. Remove the block of wood and clamp after the piston has been retracted.
- Install the new brake pads
Compare the new brake pads to the originals to confirm that they are the correct pads to install. The backing plates should be exactly the same shape. Install the new pads into the caliper. Slide the caliper assembly onto the rotor, and align the mounting or locating pins. Refer to the shop manual for the correct procedure and specifications for installing the pins or bolts. Install the pins or bolts and secure them in place. Torque the bolts or retainers to the correct specification.
- Check/remove brake system air and refit wheels
Using the correct procedure bleed the brakes and refit the wheel assemblies.
Part 1. Preparation and safety
Objective
- Safely remove and reinstall a disc brake rotor.
Safety check
- Brake components can be very hot even though they do not appear to be. Take precautions against burns when working on them.
- Always follow the manufacturer’s procedure and specifications.
- Do not allow the disc calliper to hang by the brake hose. Support it with a piece of wire.
- Properly clean and dispose of brake dust.
- Seat the brake pads in position before driving the vehicle.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Clean the mating surfaces of the hub and rotor before assembly.
- If the rotor is being replaced with a new rotor, clean it according to the installation instructions.
- Test the brake pedal to seat the brake pads before driving the vehicle.
Part 2: Step-by-step instruction
- Attach safety notice
Before working on a vehicle’s brakes, attach an appropriate label to the vehicle to prevent accidental actuation of the brake caliper while it is removed from the hub.
- Prepare the vehicle
Safely raise the vehicle and remove the wheel.
Remove the brake pads and caliper; making sure the caliper is located safely away from the rotor.
- Remove the rotor
Remove the rotor by unbolting the securing device and sliding it away from the wheel hub.
- Prepare the new rotor
Before installing the new rotor, clean it thoroughly in a component washer to remove any storage preservative agents. Clean any dirt, rust and debris from the hub mating surface. Secure the rotor to the hub and rotate it by hand to ensure it rotates freely.
- Reassemble the wheel
Refit the brake caliper and disc pads. Apply the brakes several times to readjust the caliper pistons. Refit the road wheel & safely lower the vehicle.
- Road test the vehicle
Ask your supervisor to check the brake system pedal pressure, fluid levels, and visual signs of leaks. When the supervisor is satisfied, the vehicle should be road tested by a qualified person to ensure the integrity of the braking system.
Part 1. Preparation and safety
Objective
- Check wheel cylinders, drum brake linings and measure brake drums.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Brake linings should be checked approximately every 15,000 kilometers (10,000 miles).
- Check under the dust cap to make sure that the wheel cylinder is not leaking. If you find a leaking wheel cylinder, report it to your supervisor.
Part 2: Step-by-step instruction
- Remove the drums
Some vehicles still have drum brakes or a combination of discs and drums. Passenger cars with this combination will have the drum brakes on the rear. Remove the brake drums. Be careful when you touch the brakes, they may be hot if the vehicle has been driven recently.
- Check wheel cylinders and linings
Inspect the external portion of the wheel cylinder. If the backing plate is covered with an oily substance you will need to determine if it is brake fluid or grease. Brake fluid will wash away with water so try washing it off. If it does not wash off then it is probably grease from a faulty seal. Carefully lever the rubber dust seals back, and inspect the inner portion of the cylinder for any signs of leakage.
- Check the brake shoes
Check the thickness of the brake shoe lining. You will need to consult the shop manual for the allowable minimum thickness. If the thickness is at this point or close to the minimum you must inform your supervisor. Also, if the brake shoe linings are covered in oil or grease they must be replaced. Report any signs of contamination or leakage to your supervisor.
- Check and measure the drum
Visually inspect the drum-braking surface for scoring. Any large score marks mean that the drum will have to be machined or replaced. Measure the inner diameter of the brake drum at several points around the circumference. Consult the shop manual for the specifications for an out-of-round condition. If the reading is outside the manufacturer’s specification, report it to your supervisor.
- Reassemble the drum brake
Reassemble the drum brake. Repeat the procedure for the other drum brake assemblies .
Replacing brake linings
Part 1. Preparation and safety
Objective
- Remove and replace drum brake linings.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Never use any petroleum or mineral based products, such as gasoline, kerosene etc, to clean a braking system or its components. Doing so can result in a failure of the braking system and its components. This may result in serious injury, or damage to the vehicle.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Linings are designed to withstand extreme heat generation during braking. The linings must be able to withstand these temperatures and still maintain their braking efficiency.
- Oil or grease contaminants on the lining can have an adverse effect on the co-efficient of friction of the linings.
- If you need to bleed your brakes, you may need to replace your brake fluid.
- If you are bleeding brakes on an older vehicle, or you don't know the vehicle's service history, it is good practice not to fully depress the brake pedal during bleeding.
Part 2: Step-by-step instruction
- Prepare the vehicle
Before you raise the vehicle you will need to remove some of the brake fluid from the master cylinder. Using a siphon, remove enough fluid to cause the reservoir level to be below the fill mark. This allows for a fluid expansion when you retract the wheel cylinder pistons for the new linings. Raise the vehicle using the correct procedure to a comfortable working height and remove the wheel assembly.
- Remove and inspect the brake drum
Remove the brake drum taking care to remove any locating screws and back off any manual adjusters if fitted during the removal process. Check for any signs of fluid leaks or grease leakage from a hub or axle shaft seal. Check the brake drum for any signs of cracks or other damage.
- Inspect the brake lines
Inspect the brake lines to see if there are any signs of leakage or deterioration of flexible and/or steel hoses. If replacement is required report this to your supervisor.
- Remove the brake shoes and linings
Install a brake cylinder clamp onto the wheel cylinder. This will prevent the piston coming out when you release the brake shoes. Check with the shop manual for the correct service tools you need to release the springs and clips. Using the correct tool, release the retaining clips and disconnect the return springs. Remove the worn brake shoes and their linings from the backing plate.
- Check the retaining clips and return springs
Check the condition of the return springs making sure they have not got spread coils that will reduce their efficiency. Check that the retaining clips are not damaged and will keep the brake shoes in position.
- Install the new brake shoes
Compare the new brake shoes and their linings to the original ones to make sure they are the correct replacements. Referring to the shop manual, install the brake shoes onto the backing plate. Install the return springs and retaining clips in accordance with the manufacturers specification and direction.
- Refit the brake drum
As the return spring tension takes effect, the wheel cylinder piston should move back into the cylinder. If it doesn’t you may have to manually retract the piston. Now refit the brake drum. Prepare the cylinder for bleeding using a clear bleeder hose and a jar with a small amount of brake fluid in the base. Open the bleeder screw and have your assistant slowly push the brake pedal down and observe the air bubbles coming out. Close the bleeder screw off, and have the assistant slowly release the pedal. Manually adjust the brakes if necessary to ensure that the drum rotates without binding. Refit the wheel and tire assembly using the correct procedure. Repeat this process for each of the other drum brake stations.
- Bleed system if required and test
If at the completion of the replacement process the brake pedal feels “spongy”, you should bleed the system of air from all of the brake stations. Using the correct procedure to do this, and at the completion of the job, you should recheck the system to ensure that a firm pedal is achieved, and that the wheels cannot be rotated when the brake pedal is applied. Have your supervisor check the system and verify the repair.
Adjusting a park brake cable
Part 1. Preparation and safety
Objective
- Check and adjust park brake cable following the manufacturer's procedure.
Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection – such as rubber gloves and barrier cream
- Respiratory equipment – such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- If the vehicle is being raised on a floor jack, safety stands must be used to prevent the possibility of the vehicle coming down while you are under it. Normally, the vehicle will be serviced on a hoist.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- The park brake must operate independently of the service brakes.
- Some manufacturers use an equalizer bracket to make sure that each brake station receives the same or equal pressure.
- The park brake can operate off the front or rear brakes. In some applications it operates off the back of the transmission output shaft.
Part 2: Step-by-step instruction
- Prepare the vehicle
There are two main ways of adjusting park brakes on vehicles; one method is done from underneath the vehicle, and the other from inside. A vehicle will only be fitted with one method of adjustment. The park brake is also known as the emergency brake. It must be able to operate independently from the service brakes. To check the brakes serviceability raise the car on a jack or hoist, making sure that the car is secure when raised. If you use a floor jack, make sure you support the vehicle with axle stands under the vehicle. Make sure the parking brake is off. Ensure the service brakes have been adjusted and are operative before carrying out any park brake adjustments. Check the shop manual for the correct adjustment travel for the vehicle.
- Check/adjust parking brake cable (under vehicle)
Trace the thin steel cables that run from each of the rear wheels until they meet under the car. Where they intersect there is normally a threaded rod with an adjusting nut located in a trunion. Loosen the jam nut, and turn the adjusting nut screw until the cables tighten, and then tighten the jam nut to hold the rod in place. Rotate the rear wheels to ensure they are not binding.
- Check/adjust parking brake cable (in vehicle)
Remove the protective cover from around the park brake lever or handle. Loosen the jam nut on the adjusting rod and turn the adjusting screw until the cables tighten, and then tighten the jam nut to hold the screw in place. Replace the cover over the cables to prevent any dirt entering into the vehicle. Rotate the rear wheels to ensure they are not binding.
- Test the vehicle
Lower the car, and then test it by parking on an incline, by applying the hand brake and counting the clicks to ensure that lever movement is in accordance with specifications and to make sure the brake holds the vehicle properly. While you’re driving note whether the parking light emergency light is on, if so look at the manufacturers recommendations for the correct method to adjust the parking brake sensor unit.
