Chapter 1: Overview of ETA CARS
ETA Ascon Group
ETA ASCON Group is primarily a Contracting firm in the U.A.E. with expertise ranging from Civil Construction to Electro Mechanical, Elevator Engineering and Facilities Management. Since its inception in 1973, the firm has numerous landmarks in the Emirates that stand as a testimony to the firm’s engineering capabilities. The company is a part of Al Ghurair Group of Companies, who are the most revered and leading business house in the United Arab Emirates.
ETA ASCON has enumerable divisions in every sector related to the construction industry like Joinery and Interiors, Low Voltage Switchgear Panels, Elevators, Structural Steel fabrication, Composite Aluminum Cladding, Facility Management, Janitorial and Cleaning services, etc.
These wide ranges of capabilities provide ETA ASCON the turnkey expertise to deliver a project from the drawing board to completion. ETA ASCON over the years has been involved in several commercial and residential projects in Dubai, where the Company owns premium Real Estates.
In all, the company aims to bring in its in-house expertise in the construction business gained over the last 30 years to the advantage of its customers and deliver value for money. ETA CARS

(Computerized Auto Repairs & Services, LLC) is an ISO 9001:2000 Certified Company basedinDubai,UAE.

Established in the Year 1978 marked a single most important landmark in the automotive care business and was the first automobile garage to introduce Computer Technology whose multiple functions brings out the hidden maladies and problematic areas of automobiles that comes in for check up.
It belongs to the ETA-ASCON Group and Al Ghurair Group of Companies who are the most revered and leading business house in the UAE. The ETA Group network encompasses 140 Branches and Associate Offices in 21 Countries employing over 40000 people.

Workshop is one of the leading one-stop Automobile Service and specialized in the Maintenance and Repairs of all types of Japanese, European, American and Korean Cars, heavy vehicles and equipments. Continued investment is the very latest equipment and employing well-experienced and qualified personnel, supported by a comprehensive stock of Spare Parts ensures that the company is able to offer clients expertise, which is the best.
The Workshop remains open from 8:00 a.m. to 6:30 p.m. on all 7 days and Customer can give their vehicles for service and maintenance at any time in the day and delivery of the vehicles can be organized even after the working hours with prior arrangements in the Reception.

SERVICES OFFERED Computer Diagnosis Electrical Repairs ATM / Manual Transmission Overhauling Air conditioning Repairs Brake Repairs Clutch Assembly rebuilding Engine re-conditioning Differential overhauling Major Mechanical Services

Mission reate a Bond with Customers. chieve Total Customer Satisfaction. ender Reliable Service, in Time and Every Time. trive for Continual Improvement in All Our Activities.
Purpose
Taking care of your vehicles is a major factor in achieving efficiency and safety on the roads. This is where CARS comes to the aid of Owners

Chapter 2: BRAKING SYSTEM
A brake is a mechanical device that retards or inhibits motion. It uses friction to convert the kinetic energy (moving cars etc.) into heat energy.
There are two types of brakes:
• Disc Brakes: The Disc Brake is a wheel brake that which slows rotation of a wheel by pushing brake pads against a brake disc with a set of calipers. Disc brakes are a less complex but more effective design of braking.
• Drum Brakes : It is a type of brake where the friction is caused by a set of shoes or pads that press against rotating drum shaped part called brake drum. Two types of drum brakes are - Single leading edge (1 actuator) and Double Leading Edge (2 actuators).
The advantage of using disc brakes over drum brakes is that they have better stopping performance including resistance to brake fade caused by overheating of brake components and are able to recover quickly from immersion.
Even though asbestos is mostly used, today's brake pads are made out the following
1. Organic
2. Semi-Metallic
3. Metallic
4. Ceramic In a car, when the brakes are pressed, it transmits the force from the driver's foot to the brakes through a fluid. Since the actual brakes require a much larger force than the driver could apply with his leg, the car must also multiply the force of the driver's foot. It does this in two ways:
• Mechanical Advantage (leverage)
• Hydraulic Force Multiplication.
In a hydraulic system, force applied at one point is transmitted to the other by an incompressible fluid. The fluid used is mostly an oil of some sort and the force applied is usually multiplied in order to make reduce work done. To facilitate a hydraulic system, mostly cylinders and valves are used.
Some common examples of hydraulic systems are Brakes, cranes, lifts, log cutters, hydraulic pumps etc.

Explanation: Figure 1 Hydraulic Pump Concept
The piston on the left is 2 inches in diameter while the piston on the right is 6 inches in diameter, the area therefore being 3.14 and 28.26 respectively. The piston on the left is 9 times larger than the piston on the right therefore the force transmitted from the left hand piston will come out greater on the right hand piston. Therefore, if a downward force of about 100 pound is applied to the left hand piston then an upward force of 900 pound will appear on the right hand piston.

2.1 Brake Fluids
The incompressible fluid used is Brake Fluid. It is a type of hydraulic fluid used transfer force on the brake pedal to the pressure on the brake pads in order to stop the car. Since oils are known to damage rubbers seals and hoses in braking systems, brake fluids are not petroleum based. As brake fluids are subject to very high temperature due to the immense amount of heat produced, they must have very high boiling points to avoid vaporizing in the lines. Vapor proves to be a problem since it is compressible and therefore is unable to transfer and multiply the braking force.
Boiling Points for Common Braking Fluids Dry Boiling Point Wet Boiling Point
DOT 3 205 °C (401 °F) 140 °C (284 °F)
DOT 4 230 °C (446 °F) 155 °C (311 °F)
DOT 5 260 °C (500 °F) 180 °C (356 °F)
DOT 5.1 270 °C (518 °F) 190 °C (374 °F)

DOT stands for Department of Transportation.
Glycol Ether brake fluids (DOT 3, 4 and 5.1) are hygroscopic in nature, which means they have the ability to absorb moisture whereas silicone based which is DOT 5, is hydrophobic in nature.

2.2 Disc Brakes
The Various parts of the Disc brakes are:
 BRAKE MASTER CYLINDER: Contains the brake fluid that is the incompressible fluid used in hydraulics. Figure 2 Brake Master Cylinder
 BRAKE BOOSTER: Also known as a Vacuum Servo, it assists the driver by reducing the braking effort. Figure 3 Brake Booster

 BRAKE CALIPER: Calipers are that part of the brake that pushes the brake pads against the brake disc or rotor with the help of hydraulic pistons. They are usually made up of cast iron but in some cases may be made up of composites such as reinforced carbon-carbon. Figure 4 Brake Caliper
 BRAKE PADS: They are pads that are designed for high friction with brake pad material embedded in the disc resulting in even or uneven wear. They can be adhesive or abrasive. There are varieties of brake pads such as synthetic, composite, organic and ceramic. The properties that determine material wear involve tradeoffs between performance and longevity. Figure 5 Brake Pads
ANTI RATTLE CLIPS: They are responsible for keeping the brake pads (disc brakes) and brake shoes (drum brakes) fastened. Figure 6 Anti Rattle Clips

2.3 Problems encountered found with brakes during servicing of cars
Brake Thinning: Brake thinning occurs when the brake pads wear out due to braking over time. Brake pads usually need to be changed when they go below a certain width, which is usually around 2-3mm. In such cases, the brake pads need to be changed. Figure 7 Brake Thinning
Uneven Brake thinning: This usually results in steering vibration while braking at higher speeds of around 80-100km/hr. uneven brake thinning may also occur due to the roughness or uneven surface of brake discs or rotors.
Tapered pads where one part of the brake shows a different thickness than the other occurs due to distorted caliper or sticking caliper.
Brake pads may also develop cracks as they tend to become brittle under excessively high temperatures. Another reason may be uneven flexing of pads caused due to sticking caliper. Figure 8 Brake pads Cracked
2.3.1 Brake Fade
Brake fade occurs due to repetitive and prolonged (sustained braking) especially at high speed or high load conditions. Excessive rubbing of brakes can cause the brakes to overheat and friction resin to vaporize (burn and produce smoke), and this gas forms a thin layers between the rotor and pad somewhat acting as a lubricant. Therefore, even though the braking feels firm, it is not entirely effective.
When brakes are used, as stated before, the momentum of the car, that is, the kinetic energy of the car is converted to heat energy. This is heat is transferred to the pistons and calipers and heat up the brake fluid. If the brake fluid contains moisture, it will boil forming bubbles that will further result in brake fade. This type of brake fade manifests itself in by a spongy feel on the pedal with little or absolutely no braking force. Figure 9 Brake Fade

2.4 Drum Brakes
Drum brakes are brakes that comprise of two semicircular shoes that are fixed inside a drum (spinning) which is attached to the wheel. In a single leading edge drum brake there is one actuator present between the shoes and in a double leading edge, two actuators are present between the shoes at the top and the bottom. When the brakes are applied, the actuators expand in such a way that their outer surface is pressed against the inner surface of the drum brake. The friction between the two creates heat that is in turn converted to kinetic energy that slows the vehicle down. The stopping performance of drum brakes is not as good as that of disc brakes. They are far less effective than disc brakes. Figure 10: Drum Brakes

Chapter 3. ANTI-LOCK BRAKING SYSTEM
It is an automobile safety system that allows the wheels of the vehicle to remain in tractive contact with the ground surface while the driver braking thereby preventing the wheels from locking up and avoid skidding. This particular type of system is automated and uses the principles of threshold and cadence breaking.
There are 4 main components to the Anti Lock Braking System
• Speed sensors - The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.
• Valve - There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions: In position one, the valve is open; pressure from the master cylinder is passed right through to the brake. In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder. In position three, the valve releases some of the pressure from the brake
• Pump - Since the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.
• Controller - The controller is a computer in the car. It watches the speed sensors and controls the valves. This controller is an ECU (electronic Control Unit) type.

3.1 History
3.1.1 Early systems
ABS was first developed for aircraft use in 1929 by the French automobile and aircraft pioneer, Gabriel Voisin, as threshold braking on airplanes is nearly impossible. These systems use a flywheel and valve attached to a hydraulic line that feeds the brake cylinders. The flywheel is attached to a drum that runs at the same speed as the wheel. In normal braking, the drum and flywheel should spin at the same speed. However, if a wheel were to slow down, then the drum would do the same, leaving the flywheel spinning at a faster rate. This causes the valve to open, allowing a small amount of brake fluid to bypass the master cylinder into a local reservoir, lowering the pressure on the cylinder and releasing the brakes. The use of the drum and flywheel meant the valve only opened when the wheel was turning. In testing, a 30% improvement in braking performance was noted, because the pilots immediately applied full brakes instead of slowly increasing pressure in order to find the skid point. An additional benefit was the elimination of burned or burst tires.
In 1958, a Royal Enfield Super Meteor motorcycle was used by the Road Research Laboratory to test the Maxaret anti-lock brake. The experiments demonstrated that anti-lock brakes can be of great value to motorcycles, for which skidding is involved in a high proportion of accidents. Stopping distances were reduced in most of the tests compared with locked wheel braking, particularly on slippery surfaces, in which the improvement could be as much as 30 percent. Enfield's technical director at the time, Tony Wilson-Jones, saw little future in the system, however, and it was not put into production by the company.
A fully mechanical system saw limited automobile use in the 1960s in the Ferguson P99 racing car, the Jensen FF, and the experimental all wheel drive Ford Zodiac, but saw no further use; the system proved expensive and unreliable.

3.1.2 Modern systems
Chrysler, together with the Bendix Corporation, introduced a computerized, three-channel, four-sensor all-wheel ABS called "Sure Brake" for its 1971 Imperial. It was available for several years thereafter, functioned as intended, and proved reliable. In 1970, Ford added an antilock braking system called Sure-track to the rear wheels of Lincoln Continentals as an option; it became standard in 1971. In 1971, General Motors introduced the Trackmaster rear-wheel only ABS as an option on their rear-wheel drive Cadillac models and the Oldsmobile Toronado. In the same year, Nissan offered an Electro Anti-lock System as an option on the Nissan President, which became Japan's first electronic ABS.
In 1972, four wheel drive Triumph 2500 Estates were fitted with Mullard electronic systems as standard. Such cars were very rare however and very few survive today.
In 1985 the Ford Scorpio was introduced to European market with a Bosch electronic system throughout the range as standard. For this the model was awarded the coveted European Car of the Year Award in 1986, with very favourable praise from motoring journalists. After this success Ford began research into Anti-Lock systems for the rest of their range, which encouraged other manufacturers to follow suit.
In 1988, BMW introduced the first motorcycle with an electronic-hydraulic ABS: the BMW K100. Honda followed suit in 1992 with the launch of its first motorcycle ABS on the ST1100 Pan European. In 2007, Suzuki launched its GSF1200SA Bandit with an ABS. In 2005, Harley-Davidson began offering ABS as an option for police bikes.

3.2 Operation
The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake). Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second. Because of this, the wheels of cars equipped with ABS are practically impossible to lock even during panic braking in extreme conditions.
The ECU is programmed to disregard differences in wheel rotative speed below a critical threshold, because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all roadgoing vehicles.
If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.
Modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated micro-controller. ABS is offered or comes standard on most road vehicles produced today and is the foundation for electronic stability control systems, which are rapidly increasing in popularity due to the vast reduction in price of vehicle electronics over the years.
Modern electronic stability control systems are an evolution of the ABS concept. Here, a minimum of two additional sensors are added to help the system work: these are a steering wheel angle sensor, and a gyroscopic sensor. The theory of operation is simple: when the gyroscopic sensor detects that the direction taken by the car does not coincide with what the steering wheel sensor reports, the ESC software will brake the necessary individual wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way the driver intends. The steering wheel sensor also helps in the operation of Cornering Brake Control (CBC), since this will tell the ABS that wheels on the inside of the curve should brake more than wheels on the outside, and by how much.
ABS equipment may also be used to implement a traction control system (TCS) on acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller can detect the situation and take suitable action so that traction is regained. More sophisticated versions of this can also control throttle levels and brakes simultaneously.
Upon the introduction of the Subaru Legacy in 1989, Subaru networked the four channel anti-lock brake function with the all wheel drive system so that if the car detected any wheel beginning to lock up, the variable assists the all wheel drive system installed on vehicles with the automatic transmission would engage to ensure all wheels were actively gripping while the anti-lock system was attempting to stop the car.

Figure 11: ABS in a car Figure 12: Close-Up of ABS
3.3 Components
There are four main components of ABS: speed sensors, valves, a pump, and a controller. ¬
Speed sensors
The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.
Valves
There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions:
• In position one, the valve is open; pressure from the master cylinder is passed right through to the brake.
• In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder.
• In position three, the valve releases some of the pressure from the brake.

Pump
When the ABS system operates the brake lines lose pressure. The pump re-pressurizes the system.
Controller
The controller is an ECU type unit in the car which receives information from each individual wheel speed sensor, in turn if a wheel loses traction the signal is sent to the controller, the controller will then limit the brakeforce (EBD) and activate the ABS modulator which actuates the braking valves on and off. Figure 13: Components

3.4 Uses
There are many different variations and control algorithms for use in ABS. One of the simpler systems works as follows:
1. The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 km/h) under ideal conditions, but a wheel that locks up could stop spinning in less than a second.
2. The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power.
3. When the ABS is in operation the driver will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. This pulsing also tells the driver that the ABS has been triggered. Some ABS systems can cycle up to 16 times per second.

3.5 Types of ABS
Anti-lock braking systems use different schemes depending on the type of brakes in use. They can be differentiated by the number of channels: that is, how many valves that are individually controlled—and the number of speed sensors.
Four-channel, four-sensor ABS
This is the best scheme. There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force.
Three-channel, four-sensor ABS
There is a speed sensor on all four wheels and a separate valve for each of the front wheels, but only one valve for both of the rear wheels.
Three-channel, three-sensor ABS
This scheme, commonly found on pickup trucks with four-wheel ABS, has a speed sensor and a valve for each of the front wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle. This system provides individual control of the front wheels, so they can both achieve maximum braking force. The rear wheels, however, are monitored together; they both have to start to lock up before the ABS will activate on the rear. With this system, it is possible that one of the rear wheels will lock during a stop, reducing brake effectiveness. This system is easy to identify, as there are no individual speed sensors for the rear wheels.
One-channel, one-sensor ABS
This system is commonly found on pickup trucks with rear-wheel ABS. It has one valve, which controls both rear wheels, and one speed sensor, located in the rear axle. This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in. In this system it is also possible that one of the rear wheels will lock, reducing brake effectiveness. This system is also easy to identify, as there are no individual speed sensors for any of the wheels.

Chapter 4 : HOW TO SERVICE BRAKES
4.1 General Service Procedures
The following general service procedures and precautions apply to all disc brake systems:
• Work on only one wheel at a time. Failure to do so can cause the pistons to come out of the other caliper.
• When removing a wheel, be careful not to damage the rotor, brake lines, bleeding hardware, and other components.
• Do not attempt to remove the wheel hub with the wheel and tire mounted to the vehicle. The wheel, tire, and caliper must be removed before the hub and rotor can be removed.
• Keep the caliper, rotor, and pad and plate assembly clean at all times. Avoid contact with grease, oil, and other fluids; wear safety glasses or goggles for eye protection.
• Do not allow the caliper to hang by the brake hose; the hose could split as a result. Instead, hook one end of a wire coat hanger into one of the caliper bolt holes and hang the caliper on a part of the chassis.
• Periodically check the fluid level in the master cylinder reservoirs.
• After repairing disc brakes, check for a firm pedal action before road testing the vehicle.
• NOTE: Whenever the brakes are serviced, be sure to make a thorough check for leaks in the system.

4.2 Brake Pad Check
It is important that worn disc brake pads be replaced before they cause extensive rotor damage. There are ways to determine when the pads need replacing. Some make it easy for the driver: they have built-in wear sensors that notify you when the pads are worn. In vehicles without wear sensors, the pads should be inspected visually every 10,000 to 12,000 miles. (More frequent checks are needed if the vehicle is driven under severe conditions.)
There are three types of wear sensors. They are:
1. Audible: This sensor is a soft metal tab attached to the edge of the pad backing plate that emits a high-pitched squeal when it contacts the rotating rotor face.
2. Visual: This type consists of a sensor recessed in the back of the brake pad and a warning light on the dashboard. When the rotor wears through and contacts the face of the sensor, the light is activated.
3. Tactile: This is actually two sensors: one on the rotor face and one on the lower portion of the brake pad. When the two sensors contact, a pedal pulsation is created to warn the driver.
If a visual check of the pads must be made, there are a few guidelines to keep in mind. For example, the friction material on nonmetallic pads should protrude at least 1/16" above the rivets; on semi-metallic pads, it should be at least 1/32" above the rivets. On pads that are bonded to the backing plate, the amount of friction material should equal the thickness of the backing plate. If the pads fail to meet these specifications, replace them, keeping in mind that disc brake pads should always be replaced in axle sets.
To make a complete brake pad inspection, follow these steps:
1. Engage the parking brake. Position wheel chocks behind wheels to prevent the car from rolling.
2. Use a large screwdriver (or the pointed end of the jack handle) to remove the wheel covers from the front wheels.
3. Use the wrench end of the jack handle or a socket wrench to loosen the lug nuts on both front wheels approximately one turn.
4. Jack up the front of the car until the wheels are off the ground. Position jack stands under the car.
5. Remove the lug nuts, then the wheel and tire assembly.
6. Inspect both sides of the rotor for signs of excessive wear, cracks, scoring, corrosion, discoloration, or unevenness, If any of these conditions are detected, consult a qualified mechanic.
7. Find the inspection hole on the caliper. This hole allows you to view one or both linings and judge the extent of wear without removing the caliper-provided the pads are bonded to the backing plates. If the pads are riveted, it is not possible to accurately judge the extent of wear using the inspection hole.
8. If necessary, remove the caliper and pads to inspect the pads. Figure 14: Checking Brake Pad

4.3 Caliper Removal
Keep in mind that these are general instructions. For specific directions on caliper removal, consult the service manual.
If the caliper is secured to its supports with bolts, follow these steps:
1. Push the piston back into the bore (see Piston Retraction").
2. Determine if the bolts are fastened on the outboard end of the caliper (the side resting on the outside surface of the rotor) with retaining clips.
3. If so, pull the clips off and remove the bolts.
4. Calipers retained by clips can usually be tapped out with a hammer and drift. Those secured with hex or Allen head screws must be removed with the appropriate wrench.
Calipers without bolts are usually secured at the top and bottom by slide plates. Remove them as follows:
1. Locate the spring pins holding the slide plates. There are normally two pins on each plate.
2. Pull out the pins, using needle-nose pliers, and retain them.
3. Use a screwdriver to tap out the top and bottom slide plates.
In some cases, the caliper is secured on its machined guides by a support key and screw. Remove the screw, then drive the key out of the anchor with a hammer and drift.
Once the bolts, slide plates, or key and screw have been removed, lift the caliper from the rotor. In some instances, it might be necessary to push the caliper down, then pull it away from the rotor so it clears the anti-rattle springs. Figure 15: Removing Caliper

4.4 Brake Pad Removal
Support springs, shims, retaining clips, or retaining pins may be used to hold the brake pads in the calipers. Make a note or sketch of how this hardware fits in relation to the pads before removing it.
1. Remove the pads. if the brake uses two differently shaped pads in the same caliper, note which side each pad came from.
2. Clean the caliper, disc and entire brake assembly with a good brake cleaner. If petrol eumbased fluids get on the disc or friction pad, the brake will not work.
3. While cleaning, inspect the dust boot for cracks or cuts, and check around the piston bore for signs of moisture. it the boot is damaged or fluid is leaking at the piston base, the caliper must be rebuilt or replaced.
4. Be sure all parts are dry before reinstalling the pads.
When the brake pads must be replaced, it is often recommended that the pins, springs, and clips be discarded and replaced as well. You can buy a brake pad kit that contains pads and all of the necessary hardware, as well as installation and lubrication instructions. Never reuse any parts that are worn, bent, or corroded. Figure 16 : Removing Brake Pad

4.5 Piston Retraction
Before installing the new pads, the pistons must be forced all the way back into the bores. All disc brakes are self-adjusting; as the friction pad wears thinner, the piston comes farther out of its bore to maintain a proper seat between the pad and the disc. Therefore, each piston must be pushed back into its bore to create room to slide the new, thicker pad into the caliper. (On some cars, the pistons must be pushed back even to remove the old pads.)
1. Some brake fluid should first be drained from the system to prevent the master cylinder from overflowing. Fluid is drained at the master cylinder or at the bleeder screw. Follow the instructions in the service manual carefully to avoid getting air into the system and hampering the vehicle's braking ability.
CAUTION: Never pour drained brake fluid back into the system. Refill the reservoir with new fluid of the proper type after all work is finished on both brakes but before driving the car.
2. Push the piston back into the bore, following the exact service manual instructions. Using a screwdriver or pry bar to do this procedure is not recommended, because it could damage the piston. If working on a vehicle with four-wheel disc brakes, a special tool is usually required.
3. Position a C-clamp around the caliper; tighten it to force the piston into the bore. A wood block might be needed to retract the piston.
4. If the piston fails to move with pressure, the caliper must be rebuilt or replaced. Figure 17 : Piston Retraction Tool

4.6 Reassembly
1. Insert the new pads into the caliper exactly as the old ones came out.
2. Check the assembled brake against the service manual and the brake on the opposite wheel.
3. Reinstall all pins, springs, and other removed parts, being sure to replace those that need it.
4. Finish reassembling the brake. Replace the caliper if it was removed.
5. Double-check the manual to make sure everything is back together correctly.
6. Follow the manual instructions for bleeding and closing the system, if required.
7. Be sure there is plenty of fluid in the master cylinder reservoir.
8. Pump the brake pedal slowly to reseat the pistons against the pads.
9. Reinstall the wheel assembly. Spin it while someone else operates the brake pedal to be sure the brake is operating correctly.
10. When both brakes have been serviced, lower the car and tighten the lug nuts on both wheels.
11. Test-drive the car, being alert for unusual noises and braking patterns.

4.7 Precautions

When machining a disc, you must do all the following:
1. Measure the disc before machining
2. Measure the disc after machining
3. Document the measurements on the repair order
Brake discs should be inspected for all of the following defects:
1. Hot Spots
2. Cracks
3. Warpage
A typical Drum Brake Service includes these seven operations:
Remove parts from the backing plate
Clean and inspect the parts
Replace the brake shoes
Replace or rebuild the wheel cylinders
Turn the brake drums
Lubricate and reassemble the brake parts
Pre-adjust, bleed, and test the brakes

Conclusion and Future Scope
ETA Cars is a multinational Arab Automotive company. It sells both automobiles and commercial vehicles. Ford’s largest market in the Middle East is with Saudi Arabia, Kuwait and the UAE. ETA Cars represents Ford and other European Automobile manufacturers such as Land Rover, Ferrari, Maserati and Jaguar.
We have been given orientation to all the sections in the workshop by the respective section heads. They were very helpful and explained to us how they diagnose the faults and how the repair works are done for different cars. I was particularly interested in the working on engines. Engine repairs are carried out by technician Mr. Arumughan. He explained to us the repair works on a Lumina 6.2L V8 engine.
Over the past five and half months I gained considerable amount of knowledge in vehicle repair and servicing. We could well related the theoretical knowledge gained in the Automotive Vehicles course which we had learnt the previous semester and the practical work done in the workshop. We had done a survey in the company also. This survey can help the company to improve its services and improve customer satisfaction.

References www.carbibles.com www.wikipedia.com www.howstuffworks.com Ford Model Books Year 2008 to 2011