MECH 4010 & 4015
Design Project I
CONCEPTUAL DESIGN REPORT
Formula SAE Brake Rotor Optimization
Team #2
Supervised by
Dr. Jimmy Chuang
Team Members:
Alex Burgess
Karim Shaloh
Megan Tunney
HanOu Xu
Submitted: November 8th, 2013
Table of Contents
Table of Contents ................................................................................................................ ii
List of Illustrations ............................................................................................................. iii
Figures ........................................................................................................................... iii
Tables ............................................................................................................................. iii
1.0 Project Information ....................................................................................................... 1
1.1 Project Title............................................................................................................... 1
1.2 Project Customer(s) .................................................................................................. 1
1.3 Group Members ........................................................................................................ 1
2.0 Conceptual Design Summary ....................................................................................... 2
3.0 Background and Context............................................................................................... 3
4.0 Requirements ................................................................................................................ 6
4.1 Technical Requirements............................................................................................ 6
4.2 Performance Requirements ....................................................................................... 6
4.3 Scheduling Requirements ......................................................................................... 7
4.4 Miscellaneous Requirements .................................................................................... 7
5.0 Concept Combination Tables ........................................................................................ 8
6.0 Overview of Conceptual Solution Alternatives ............................................................ 9
6.1 Rotor Alternatives ..................................................................................................... 9
6.1.1 Plain Rotor ....................................................................................................... 10
6.1.2 Drilled Rotor .................................................................................................... 11
6.1.3 Slotted Rotor .................................................................................................... 13
6.1.4 Drilled and Slotted Rotor ................................................................................. 14
6.1.5 Summary of Rotor Alternatives ....................................................................... 15
6.2 Carrier Alternatives ................................................................................................. 16
6.2.1 Curved Spokes Carrier ..................................................................................... 16
6.2.2 Slanted Spokes Carrier ..................................................................................... 16
6.2.3 Star Carrier ....................................................................................................... 17
6.2.4 Summary of Carrier Alternatives ..................................................................... 18
7.0 Overall Design ............................................................................................................ 18
8.0 Testing and Verification ............................................................................................. 18
9.0 Required Engineering Expertise ................................................................................. 20
10.0 Resources and References......................................................................................... 21
10.1 Facilities ................................................................................................................ 21
10.2 Additional Advisors .............................................................................................. 21
10.3 Funds ..................................................................................................................... 22
References ......................................................................................................................... 23
Appendix A ....................................................................................................................... 24
Appendix B ....................................................................................................................... 24
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List of Illustrations
Figures
Figure 1: Disc Brake Assembly .......................................................................................... 3
Figure 2: Floating Disk Brake............................................................................................. 4
Figure 3: Current Design .................................................................................................. 10
Figure 4: Current design stress analysis............................................................................ 10
Figure 5: Plain rotor .......................................................................................................... 11
Figure 6: Plain rotor stress analysis .................................................................................. 11
Figure 7: Drilled rotor ....................................................................................................... 12
Figure 8: Drilled rotor stress analysis ............................................................................... 12
Figure 9: Slotted rotor ....................................................................................................... 13
Figure 10: Slotted rotor stress analysis ............................................................................. 13
Figure 11: Slotted and drilled rotor ................................................................................... 14
Figure 12: Slotted and drilled rotor stress ......................................................................... 15
Figure 13: Curved spokes conceptual design.................................................................... 16
Figure 14: Slanted spokes conceptual design (yotambike.blogspot.ca) ........................... 17
Figure 15: Star carrier conceptual design (diytrade.com) ................................................. 17
Tables
Table 1: Concept combination table ................................................................................... 8
Table 2: Mass and stress comparison for each design ...................................................... 15
Table 3: Carrier Design Advantage Score ........................................................................ 18
Table 4: Testing and verification ...................................................................................... 19
Table 5: Group Engineering Expertise ............................................................................. 20
Table 6: Expenses Estimation ........................................................................................... 22
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1.0 Project Information
1.1 Project Title
Dalhousie Formula SAE Brake Rotor Optimization
1.2 Project Customer(s)
Dalhousie Formula SAE Team
Kirk Fraser
Kirk.Fraser@dal.ca
(902) 403-5475
1.3 Group Members
Name
Megan Tunney
Alex Burgess
Karim Shaloh
HanOu Xu
2013-11-08
Contact Information (Email/Phone)
mg640491@dal.ca
(902) 441-7927
alex.burgess@dal.ca
(902) 408-8240
kshaloh@dal.ca
(902) 401-6440
hn717082@dal.ca
(902) 402-5396
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Conceptual Design Report
2.0 Conceptual Design Summary
This report will outline the requirements for the MECH 4010 Design Project in
conjunction with the Formula SAE Brake Rotor Optimization. The document will
establish the background, the requirements and concept generation of the project. Several
designs alternatives will be presented and then evaluated for feasibility. These designs
include the rotor and center alternatives. Finally the teams’ plans for testing as well as the
resources will be presented to confirm the validity of the project.
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3.0 Background and Context
A brake is a mechanical device which when applied constrains motion causing a vehicle
to slow down. The most common type of brakes is the functional brake which includes
band brakes, drum brakes and disc brakes.
Disc brakes, as shown in figure 1, use a mechanism called a brake caliper and brake pads
to slow the movement of the wheels. A disc, generally made of cast iron, is connected to
the wheel and axle and spins directly with the wheels. A caliper hovers around the disc
while it spins. When the brake pedal is engaged the caliper hydraulically presses the
brake pads against the disc causing a frictional buildup. The friction causes the disc to
eventually come to a stop transferring the built up kinetic energy into thermal energy
which is dispersed into the environment.
Figure 1: Disc Brake Assembly
(Automotive Talkline, Brakes: Important for your Safety)
One of the most common types of disc brakes, and commonly used in high performance
vehicles, is the floating disc brake. This system involves a floating rotor and a center as
opposed to a solid disc as shown in figure 2. The center is attached to a hub which rotates
directly with the wheel. The rotor sits radially outwards from the center and is attached to
the center with several buttons. The rotor is considered floating as it is free to move
slightly laterally with the width of the buttons. The buttons do restrict movement of the
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Conceptual Design Report
rotor in the angular and rotational direction. The benefit of this system is that any
warping or misalignment in the wheel or rotor mounting face can be compensated by the
floating movement. Any vibration felt by the wheels will be separated from the center not
allowing the movement to be carried through to the suspension or steering.
The float buttons allow the rotor to have a
degree of freedom in the lateral direction.
BRAKE CALIPER
FLOAT BUTTONS
BRAKE ROTOR
ROTOR CARRIER
Figure 2: Floating Disk Brake
The Dalhousie Formula SAE team seeks to improve the performance of their vehicle’s
braking system. This design project will include examining the current braking rotor
system and optimizing the design. Factors such as material, weight, heat transfer and
machining will be considered to enhance the current design.
An optimization of the brake rotor design will be beneficial to the performance of the
vehicle. The weight of the vehicle is crucial to the success of the car and by reducing the
weight of the rotors by selecting different materials and cut-out pattern it will contribute
to the reduction of overall weight. Another vital component to the operation of the
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vehicle is the reliability or lifespan of its parts. By increasing the lifespan of the rotors
they will not need to be replaced as frequently resulting in a lower overall cost for the
braking system. By analyzing the rotor and fastener stress under performance loading it
can be determined which material and design will be the best option for success.
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4.0 Requirements
The following is a list of requirements the team believes the design must accomplish by
the end of the term.
4.1 Technical Requirements
 The design must be capable of withstanding a force, 730N, strong enough to lock
all four wheels at a speed of 60 km/hr.

The design must weigh 15% less than that of the current design weight.

The design must not exceed the allowable budget of $1500.

The design must be constructed to work with ISR 4-piston calipers (22-045) and
Tilton 77 Series Master Cylinders.

The design must include a method of attaching a data acquisition device (trigger
wheel) to monitor testing.
4.2 Performance Requirements
 The design must perform basic braking maneuvers and tests set out by the
Formula SAE organization.
o The brake system will be dynamically tested and must demonstrate the
capability of locking all four (4) wheels stopping the vehicle in a straight
line at the end of an acceleration run specified by the brake inspectors. 2014 Formula SAE Rules
o After accelerating the tractive system has to be switched off by the driver
and the driver has to lock all four wheels of the vehicle by braking. The
brake test is passed if all four wheels simultaneously lock while the
tractive system is shut down. -2014 Formula SAE Rules

The design must be compatible with the 2014 hubs and uprights, specified by the
Formula SAE team.

The design must be able to withstand multiple testing trials and driving runs.
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
The design must be able to be installed by member of the design team and
Formula SAE team.

The design must not affect the performance of the car negatively.

The design must optimize the performance of the vehicles braking system.
4.3 Scheduling Requirements
 The design must not be critical to the completion of the 2014 Formula SAE car,
competing in May 2014.

The design must be completed within the given time range, before the finish of
the MECH 4010, by the end of March 2014.
4.4 Miscellaneous Requirements
 The design must ensure the safety of the driver and persons in the surrounding
area.

The design must conform to all the rules and regulations of the MECH 4010
design project as outlined in the MECH 4010 Outline and Manual.

The design must conform to the rules and regulations set out by the Formula SAE
organization as outlined in the 2014 Formula SAE Rulebook.
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5.0 Concept Combination Tables
The following concept combination table displays the sections of the project in which the
team is analyzing and possible solutions the team is exploring. The problem is split into
the rotor, center and the button type. Each of these areas then has a list of possible
materials that can be used for the final design. Through further analysis a solution from
each column will be selected combining to a final design. For better comparison in
masses and stresses, in this report AISI 304 Stainless Steel will be applied to all
SolidWorks models.
Table 1: Concept combination table
Rotor Type
Rotor Material
Blank
Titanium
Center
Material
Titanium
Button
Material
Titanium
Drilled
Aluminum
Aluminum
Aluminum
Slotted
High Strength
Steel
Reinforced
Carbon Fiber
Cast Iron
High Strength
Steel
Reinforced
Carbon Fiber
Cast Iron
High Strength
Steel
Reinforced
Carbon Fiber
Cast Iron
Ceramic
Ceramic
Ceramic
Drilled/Slotted
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Center Type
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6.0 Overview of Conceptual Solution Alternatives
When designing the rotor, there are two parts to consider: the outer disc and the carrier.
The outer disc is the portion that makes contact with the pads and the carrier is the center
of the rotor that connects the outer disc to the bolts on the hub.
Each part has a separate challenge to overcome, while both parts will contribute to the
overall weight reduction challenge. The main challenge the outer disc needs to overcome
is the accumulation and dissipation of heat. Section 6.1 will discuss four different design
alternatives to solve this problem. The main challenge the carrier needs to overcome is
bending stress. Section 6.2 will discuss three different design alternatives to solve this
problem and propose a solution.
6.1 Rotor Alternatives
The current design has an outer diameter Do = 270.3 mm, and a thickness t = 5.25 mm.
Holes are drilled in a pattern shown in Figure 3, five holes in series, 24 repeat in a circle.
AISI 304 stainless steel is applied to model as manufacturing material. Considering a
safety factor of 3, the allowable stress for AISI 304 is 68.9 MPa. Figure 4 shows the max
stress in the current design is 1.27 MPa, which is much less than allowable stress. The
stress is larger at the inner side of the ring. Mass of the rotor is 793.39g. To optimize the
current rotor design, the following four conceptual designs have come up:

Plain rotor with reduced thickness

Drilled rotor with reduced thickness

Slotted rotor with reduced thickness

Slotted and drilled rotor with reduced thickness
The thickness will be all reduced to 3.5 mm. To determine the feasibility of the different
rotor designs several preliminary SolidWorks Simulation were done. These simulations
evaluated the previous design of the brake rotor as well as other possibilities of the rotor
design. Each conceptual design will be discussed with its stress analysis graphic result.
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Figure 3: Current Design
Figure 4: Current design stress analysis
6.1.1 Plain Rotor
The plain rotor design has a thickness of 3 mm and there are no drilled holes or slots on
the ring Figure 5. It has a mass of 444.27g. The stress analysis shows that the maximum
stress in the rotor is as low as 0.89 MPa (Figure 6). This design is very robust, reliable
and can withstand a lot of stress. Also, the cost should be low for this design. The
disadvantage is that it does not decrease the weight effectively.
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Figure 5: Plain rotor
Figure 6: Plain rotor stress analysis
6.1.2 Drilled Rotor
The drilled rotor design has a thickness of 3.5 mm and the hole-pattern has increased
from 24 to 28 repeated per circle (Figure 7). Figure 8 shows a simulation of the stresses
applied to a drilled rotor. The red arrow pointing down at the center is gravity and the
pointing to the right is the deceleration during stop test. It is seen that the majority of the
stress lies in the inner edge of the rotor. Mass of the rotor is decreased to 528.93 g as
more holes are created on the ring. The maximum stress on the rotor is 1.93 MPa. This
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design has decreases the mass of original design by 33.33% which is remarkable for only
a slight increase in maximum stress. This design should have good reliability and does
not take a lot of effort to make. However, as a high performance rotor is aimed, the
preference is to decrease the mass as much as possible; thus, the maximum stress could
be further increase to give a lighter design.
Figure 7: Drilled rotor
Figure 8: Drilled rotor stress analysis
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6.1.3 Slotted Rotor
For the third conceptual design, 28 slots are drilled on the rotor in a circular pattern
(Figure 9). In this case, the rotor weighs 444.27g, which is a 44% mass reduction from
the original design. As Figure 10 shows, the maximum stress goes up to 5.23 MPa yet is
still within the allowable stress range (68.9 MPa). This design should be easy to machine
and the cost will not be very high; it looks satisfying overall, but there might be space to
be further improved.
Figure 9: Slotted rotor
Figure 10: Slotted rotor stress analysis
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6.1.4 Drilled and Slotted Rotor
A drilled and slotted rotor design is create based on the principal of taking out material as
evenly as possible. 24 repeat of slots and holes pattern are created on the rotor. Slotted
and drilled conceptual design result is shown in Figure 11. This design has a mass of
387.13g, which is 51.21% reduced from the current design. Figure 12 illustrates the stress
distribution on the rotor. The maximum stress in the rotor increases to 11.0 MPa. In this
design, a good mass reduction is achieved. The tradeoff is that stress significantly
increases, though it is still not exceeding the allowable stress for the material (AISI 304).
This is the preferable conceptual design among the four based on mass reduction. The
disadvantage is the pattern might be difficult to machine and it might cost a lot more to
do so. Further analysis such as thermal expansion and buckling effect will be conducted
to make sure there is no significant disadvantage of this design.
Figure 11: Slotted and drilled rotor
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Figure 12: Slotted and drilled rotor stress
6.1.5 Summary of Rotor Alternatives
The mass reduction and maximum stress of each design is shown in Table 2 for a better
comparison:
Table 2: Mass and stress comparison for each design
Conceptual
Designs
Original
Plain
Drilled
Slotted
Slotted and drilled
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Mass (g)
793.39
594.9
528.93
444.27
387.13
Mass Reduction
(g)
N/A
198.49
264.46
349.12
406.26
15
Reduced %
N/A
25.02%
33.33%
44.00%
51.21%
Max. Stress
(Mpa)
1.27
0.89
1.93
5.23
11.0
Conceptual Design Report
6.2 Carrier Alternatives
The current carrier design similar to that of figure 2 consists of eight uniform straight
spokes. All eight spokes are evenly spaced and are subjected to equal bending stress.
The following three conceptual designs will aid in optimizing the bending stress:

Curved spokes carrier

Slanted spokes carrier

Star carrier
6.2.1 Curved Spokes Carrier
Figure 13 shows the curved spokes Carrier. It will be mounted to rotate counter clock
wise when the car is moving forward. The advantages of this design are that it will be
able to withstand bending stress better than the slanted design and it weighs the least.
Figure 13: Curved spokes conceptual design
The disadvantages of this design is that it will be harder and more expensive to machine
and it may create a challenge in mounting the sensor for the tractive system.
6.2.2 Slanted Spokes Carrier
Figure 14 shows the slanted spokes Carrier. It will be mounted to rotate counter clock
wise when the car is moving forward. The advantages of this design are that it will be the
easiest to machine and cost the least. It will also give a little bit more room than the
curved design to mount the tractive system sensor.
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Figure 14: Slanted spokes conceptual design (yotambike.blogspot.ca)
The disadvantage of this design is that because the spokes are slanted some of the
bending force will be axial force which will add shear stress on the bolts; this may create
a new challenge that wasn’t initially accounted for.
6.2.3 Star Carrier
Figure 15 shows the star carrier. The advantages of this design are that it will be able to
withstand bending stress the best and allow for lots of room to mount the tractive system
sensor.
Figure 15: Star carrier conceptual design (diytrade.com)
The disadvantages of this design are that it will be hardest and most expensive to
machine. It also weighs the most.
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6.2.4 Summary of Carrier Alternatives
The following table will rank the weight, cost, ease of machining and ease of sensor
mounting of the three alternative designs. A score of 1 is best and 3 is worst.
Table 3: Carrier Design Advantage Score
Conceptual
Designs
Curved Spokes
Slanted Spokes
Star
Weight
Cost
1
2
3
2
1
3
Ease of
Machining
2
1
3
Sensor
Mounting
3
2
1
Total
Based on the above scores, it’s best to go with the slated spokes carrier design.
7.0 Overall Design
In evaluating the alternative solutions a decision matrix will be applied. Several criteria
have been chosen to assess the solutions to determine which will be the most successful.
The criteria are as follows:

Weight: The design will be of minimal weight

Cost: The design will be of minimal cost

Ease of Machining: The design will require minimal machining

Machining Time: The design will require minimal machining time

Reliability, Lifespan: The design will be reliable with a long lifespan (≥1 yr.)
In the decision matrix each criteria will be assigned a value or weight dependent on how
important the team believes the criteria is to the final design. Each solution will then be
evaluated on each criterion rating the solution that best describes the criteria to the
solution that worst describes the criteria. The number will then be multiplied by the
corresponding criteria weighting. The successful solution will be the solution with the
best results.
8.0 Testing and Verification
To determine the success of the design, the braking system must be tested and evaluated
against the previous design. The following are areas in which the team has determined
crucial for testing and the methods in which they will be tested.
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8
6
10
Table 4: Testing and verification
Testing Area
Weight
Dimensions
Heat Transfer
Rotor Material Strength
Temperature during Runs
Buttons/Fasteners Strength
Testing Method
Direct Measurement
Direct Measurement
Theoretical Analysis (heat transfer), FEA Analysis
Theoretical Analysis (material stress/strain), Sacrificial
Part, FEA Analysis
Theoretical Analysis (heat transfer), Dry Runs
Theoretical Analysis (material stress/strain), Sacrificial
Part, FEA Analysis
Weight and Dimensional testing will be done through direct measurements. This will
include measuring the previous design and the new design on scales and determining the
dimensions by means such as a caliper or micrometer.
Tests involving heat transfer will be mainly done through theoretical calculations and
SolidWorks Simulations. The team will be determining how the heat is dispersed
throughout the rotor during braking due to friction build up from the applied calipers.
This test will be crucial in selecting a material which can withstand the heat buildup
during braking. Determining this temperature buildup will also be tested during dry runs
of the braking system. A test including setting the car and braking system up with a
dynamometer will allow us to see how the braking system will react at maximum speeds.
A heat gun or infrared camera will determine the areas of the rotor which experience the
most temperature buildup.
An analysis of the material strength of the rotors, the center, and the buttons is another
area of significant importance. Initial testing of theoretical calculations and SolidWorks
Simulations will determine the point at which the material will fail. By applied theories
of bending and shear stress we can evaluate materials which will perform better for the
given application.
The previously described tests will be performed on both the previous rotor design as
well as the newly designed rotor. This will allow the team to evaluate the success of the
newly designed system meeting the proposed requirements. Initial tests including weight,
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dimensions, heat transfer, and material strengths will be done on the previous design
immediately. The results of these tests will determine a set point on which the new design
needs to improve. Once the results have been analyzed the tests will be rerun on different
designs and materials to determine an optimal design. Initially theoretical calculations
and SolidWorks Simulation will be run on the designs to determine the best solution.
Once a prototype has been manufactured testing including runs on a Dynamometer and
dry runs with the car will be done.
9.0 Required Engineering Expertise
The design team has identified the following engineering expertise topics as areas in
which the majority of our analysis will come from. In each technical area a team member
has been identified as the expertise. This member will lead the team in each technical
area with support from the rest of the design team.
Table 5: Group Engineering Expertise
Technical Area
CAD (SolidWorks)
CAD Simulations/FEA
Analysis (SolidWorks)
Material Stress/Strain
Heat Transfer
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Team Member Responsible
HanOu Xu
Alex Burgess
HanOu Xu
Megan Tunney
Alex Burgess
Megan Tunney
Karim Shaloh
Karim Shaloh
HanOu Xu
20
Level of Expertise
Advanced
Intermediate
Advanced
Intermediate
Intermediate
Intermediate
Intermediate
Intermediate
Intermediate
Conceptual Design Report
10.0 Resources and References
The following section will outline resources the team has determined will be critical to
the completion of the project. The section will outline the facilities the team will use, the
additional advisors the team will seek advice from, and the area in which the project
funding will come from.
10.1 Facilities
The following are resource facilities that will provide support crucial to the completion of
the design project. Access to these shops with the permission and supervision of the
respective people will determine the success of the design project.

Machine Shop- with permission of machine shop supervisor

Formula SAE Shop- with permission of the team

Vendor Machine Shops-with permission of shop supervisor
10.2 Additional Advisors
The following persons are ones who the team believes will be able to provide additional
knowledge to the project throughout the design process. Consultations with these
advisors and other persons deemed relevant will be made during the design project term.

Dr. Jim Chuang- Team Advisor

Dr. Peter Allen- Heat Transfer

Dr. Julio Militzer-Fluid Dynamics, Engines

Dr. Ted Hubbard- Brake Design

Dr. Andrew Warkentin- Manufacturing

Angus MacPherson- Machine Shop Supervisor

Albert Murphy- Technician, Testing

Peter Jones- Engineering Testing-Dynamometer
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10.3 Funds
The Mechanical Engineering Department will make funds of approximately $1500
available to the team. Any additional resources, with sufficient reason, will be supplied
by the Formula SAE team. It has been strongly recommended the team seek out
sponsorship for additional funding and as such the design team will pursue sponsorship
when necessary. The following are areas in which the team believes the majority of the
supplied funds will be spent.
Table 6: Expenses Estimation
Materials
Machining
Testing
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30%
45%
25%
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References
Car Bibles, ‘The Brake Bible’, http://www.carbibles.com/brake_bible.html#. Accessed
November 2013.
Moore, C., Automotive Talkline, ‘Brakes: Important for your Safety’,
http://corymmoore.wordpress.com/tag/disc-brakes/. Accessed November 2013.
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Appendix A
Appendix B
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