1985-89 toyota MR2 power steering - UC DRC Home
Transcript of 1985-89 toyota MR2 power steering - UC DRC Home
1985-89 TOYOTA MR2 POWER STEERING
A Baccalaureate thesis submitted to the School of Dynamic Systems
College of Engineering and Applied Science University of Cincinnati
in partial fulfillment of the
requirements for the degree of
Bachelor of Science
in Mechanical Engineering Technology
by
Adam Close
April 2013
Thesis Advisor: Dr. Janak Dave
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TABLE OF CONTENTS
TABLE OF CONTENTS ........................................................................................................... I
LIST OF FIGURES .................................................................................................................. II
LIST OF TABLES .................................................................................................................. III
ABSTRACT ............................................................................................................................ IV
INTRODUCTION AND RESEARCH ..................................................................................... 1
PROBLEM STATEMENT ........................................................................................................................................ 1 INTERVIEWS ........................................................................................................................................................ 2 HYDRAULIC POWER STEERING ........................................................................................................................... 3 FLAMING RIVER POWER STEERING RACK WITH TILT COLUMN ......................................................................... 4 ELECTRO-HYDRAULIC POWER STEERING ........................................................................................................... 5 MK2 POWERED MK1 MR2 .................................................................................................................................... 5 ELECTRIC POWER STEERING .............................................................................................................................. 6 UNIVERSAL ELECTRA-STEER ............................................................................................................................. 7 ADJUSTABLE POWER STEERING ......................................................................................................................... 8 STEER-BY-WIRE .................................................................................................................................................. 9
CUSTOMER FEEDBACK, FEATURES AND OBJECTIVES ............................................ 10
SURVEY ANALYSIS ............................................................................................................................................ 10 PRODUCT FEATURES AND OBJECTIVES .............................................................................................................. 11 ENGINEERING CHARACTERISTICS ...................................................................................................................... 12
DESIGN ALTERNATIVES AND SELECTION .................................................................. 13
LOADING CONDITIONS CALCULATIONS ..................................................................... 14
COMPONENT AND MATERIAL SELECTION.................................................................. 17
FABRICATION AND ASSEMBLY ...................................................................................... 20
TESTING AND PROOF OF DESIGN .................................................................................. 25
SCHEDULE AND BUDGET ................................................................................................. 26
SCHEDULE ........................................................................................................................................................ 26 BUDGET ............................................................................................................................................................ 27
RECOMMENDATIONS ........................................................................................................ 28
WORKS CITED ..................................................................................................................... 29
APPENDIX A - RESEARCH ................................................................................................... 1
APPENDIX B - SURVEY ........................................................................................................ 1
APPENDIX C – PRODUCT OBJECTIVES ............................................................................ 1
APPENDIX D – QUALITY FUNCTION DEPLOYMENT .................................................... 1
APPENDIX E – CALCULATIONS ......................................................................................... 1
APPENDIX F – SCHEDULE ................................................................................................... 1
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APPENDIX G - BUDGET ....................................................................................................... 1
APPENDIX H – DRAWINGS ................................................................................................. 1
APPENDIX I – PRESENTATION ........................................................................................... 1
APPENDIX J – WIRING DIAGRAM ..................................................................................... 1
APPENDIX K – WIRE ROUTING .......................................................................................... 1
LIST OF FIGURES Figure 1 - Hydraulic Power Steering ........................................................................................ 3
Figure 2 - Flaming River Mustang Kit ..................................................................................... 4
Figure 3 - Electro-Hydraulic Power Steering ........................................................................... 5
Figure 4 - Electric Power Steering ............................................................................................ 6
Figure 5 – Universal Electra Steer ............................................................................................ 7
Figure 6 - Before Installation .................................................................................................... 8
Figure 7 - After Installation ...................................................................................................... 8
Figure 8 – Steer-By-Wire .......................................................................................................... 9
Figure 9 – Column Design ...................................................................................................... 13
Figure 10 – Steering Effort ..................................................................................................... 14
Figure 11 – Solid Model Assembly ........................................................................................ 14
Figure 12 – Exploded Stress Area .......................................................................................... 14
Figure 13 – Stress Concentration Factor Graph ...................................................................... 15
Figure 14 - Easysteer .............................................................................................................. 17
Figure 15 – Coupler ................................................................................................................ 18
Figure 16 – Rod ...................................................................................................................... 19
Figure 17 – Tube ..................................................................................................................... 19
Figure 18 – Stock Column Disassembled ............................................................................... 20
Figure 19 – Cutting the Stock Column ................................................................................... 20
Figure 20 – Cut Upper Shaft ................................................................................................... 20
Figure 21 – Splined Shaft ....................................................................................................... 21
Figure 22 – Upper Shaft Assembly ......................................................................................... 21
Figure 23 – Lower Shaft Components .................................................................................... 21
Figure 24 – Lower Shaft Assembly ........................................................................................ 22
Figure 25 – Alignment Marks ................................................................................................. 22
Figure 26 – Upper and Lower Body Alignment ..................................................................... 23
Figure 27 – Power Steering Column Disassembled ............................................................... 23
Figure 28 – Power Steering Column Assembled .................................................................... 23
Figure 29 – Knob Location ..................................................................................................... 24
Figure 30 – Power Steering Column Installed ........................................................................ 24
Figure 31 – Effort of 7 lbs....................................................................................................... 25
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LIST OF TABLES Table 1 – Survey Results 10
Table 2 – Engineering Characteristics 12
Table 3 – Design Evaluations 13
Table 4 – Stress Analysis 16
Table 5 – Spring Pins 18
Table 6 – Schedule 26
Table 7 – Budget 27
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ABSTRACT The 1985-89 Toyota MR2 is lighter than most cars but can still benefit greatly with the
use of power steering. Currently, there are no power steering kits for the MR2. One person
managed to incorporate power steering into his MR2 in two different ways. His first attempt
had poor results and the second attempt was successful but did not reveal much information
about it.
By exploring the different types of power steering and conducting interviews, product
features are developed and put into a survey that are voted on by importance. These features
are then put into measurable goals called Objectives. From there, three types of power
steering designs are rated based on their performance in with the Objectives. The result is an
Electric Power Steering System that reduces the driver’s steering effort by as much as 62%
and bolts directly in place of the old MR2 column with minor modifications around the dash
area. The design takes the original column’s one piece body and one piece shaft and cuts out
the middle sections of both and integrates an electric motor in their place.
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INTRODUCTION AND RESEARCH
PROBLEM STATEMENT The 1985-89 Toyota MR2 is a mid-engine, rear-wheel-drive, two-seater. It is a great
commuter car because it gets up to 32 highway miles per gallon and fits into tight parking
spaces. The only problem is it never came with power steering which makes parking a bit
more of a hassle and sometimes dangerous. One example that shows this is parallel parking
on a busy city street. It must be done quickly and accurately. Without power steering, the
driver must use the strength of both hands and the mirrors without the ability to turn around
and look directly where he or she is going like most driver’s like to do. This takes a little
more time and possibly a few tries which is dangerous in heavy traffic. Although the MR2 is
lighter than most cars it is still heavy enough to benefit from power steering.
A power steering kit for the MR2 will give the driver the ability to turn the steering wheel
with the palm of one hand and make it safely into a parking spot.
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INTERVIEWS Interviews with daily commuters are conducted to find what features are enjoyed most.
In an interview with Paula Walker, it is found that she use to drive a 1956 Buick Special
that had a semi truck size steering wheel and no power steering. She feels that non-power
steering is not difficult on city streets except when parallel parking. Paula says vehicles with
power steering are much easier to drive all-around and prefers a modern size steering wheel
with power steering. (1)
Jen Walker drives a 2004 Infinity G35 and likes how responsive the steering is. (2)
Joyce Close remembers driving a 1995 Ford Van and a 2000 Ford 350 Truck in which
both power steering systems developed play. Her only desire is for a reliable power steering
system. (3)
Dan Close is not only a daily commuter but also a novice racecar driver. His only care
for his daily driver is that it has low steering effort. As for his racecar, he needs to have
responsive steering. (4)
After getting to know what commuters think about their power steering features, power
steering systems are explored to find advantages and disadvantages.
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HYDRAULIC POWER STEERING There are four types of power steering that use a rack and pinion. They are Hydraulic
Power Steering (HPS), Electro-Hydraulic Power Steering (EHPS), Electric Power Steering
(EPS) and Steer-By-Wire.
In Hydraulic Power Steering, a pulley driven pump mounted on the engine forces
hydraulic fluid through a control valve on the steering column and into the power steering
rack on both sides of a piston as shown in Figure 1 (5). When the steering wheel is turning, a
thin torsion bar inside the control valve is being twisted letting more fluid into one side of the
piston and forcing it to help turn the wheels proportional to the amount of torque being
applied to the steering wheel. An advantage of HPS over EHPS and EPS is that it doesn’t use
electronics making it easier to work on for the Do-It-Yourself (DIY) person. The
disadvantages are leaking hydraulic fluid, routine maintenance, and needing to run hydraulic
lines from the rack to the pump on the engine. Also, because the HPS pump is driven by the
engine, it decreases horsepower, fuel economy and the pump’s life because it is running all
the time.
Figure 1 - Hydraulic Power Steering
HPS is still the most common type in today’s vehicles. Less common vehicle designs
will be discussed later for using other power steering systems. One aftermarket company that
sells HPS kits for vehicles without power steering is Flaming River.
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FLAMING RIVER POWER STEERING RACK WITH TILT COLUMN Flaming River is a company that makes steering components like power steering racks
for domestic muscle cars that didn’t come with them from the factory. Among them is a
power steering kit for the 1965-70 Ford Mustang shown in Figure 2 (6). The company
claims, “They feature a cradle that mounts in the original chassis location with no
modification, and the center support does not have to be removed. The kits include: a new tilt
steering column with universal joints, shafting, support bearing, billet aluminum reservoir,
power rack and pinion, and mounting cradle. They also include all grade 8 mounting
hardware and a variable pressure pump for true-steering driving performance.”
Figure 2 - Flaming River Mustang Kit
The next type of system is Electro-Hydraulic Power Steering.
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ELECTRO-HYDRAULIC POWER STEERING Electro-Hydraulic Power Steering works the same as HPS except that it uses an electric
motor to drive the pump instead of the engine and pulley. Along with the control valve the
EHPS also uses a computer that takes the vehicles speed into consideration and adjusts the
amount of force used to help turn the wheels. The advantages of EHPS are being able to
place the motor and pump anywhere, increased pump life and does not reduce horsepower
and fuel economy. The disadvantages are it still leaks fluid and requires routine maintenance.
Figure 3 (7) shows a diagram of the EHPS.
Figure 3 - Electro-Hydraulic Power Steering
Car manufactures typically use EHPS when the engine is in the rear of the vehicle. This
eliminates installing lengthy and complex shaped hydraulic lines. No aftermarket kits are
available but some people integrate systems from vehicles that came with them into their
own vehicle. One example is Paul Woods and his MK2 powered MK1 MR2.
MK2 POWERED MK1 MR2 In the Adjustable Power Steering discussion on www.imoc.co.uk that will be mentioned
more later, Paul Woods mentions, “A few years ago I retro fitted a Mk2 PAS system onto a
Mk1 using a USDM rack, turned upside down, and then fitted all of the Mk2 pump and
control system, it worked but it was heavy and made the Mk1 feel funny to steer.” Mk1
refers to a 1985-89 MR2 and an Mk2 is a 1991-98 MR2. PAS stands for Power Assisted
Steering (8).
The next type of system is Electric Power Steering.
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ELECTRIC POWER STEERING Electric Power Steering uses an electric motor that is attached directly to the steering
column or inside the steering rack, as seen in Figure 4 (5), and applies force to turn the
wheels. This motor is connected to a computer that reads signals from a torque sensor and
steering wheel angle sensor on the steering column and a signal of the vehicles speed, similar
to EHPS. It then calculates the amount of force needed for the motor to help turn the wheels.
The advantages of EPS are less components, light weight, quiet, not having any fluid to leak
making it maintenance free, increased life because it only runs when the steering wheel is
turning, does not use horse power that decreases fuel economy and can have the ability to
adjust the amount of overall assist to the user’s preference. The disadvantages are there needs
to be room to mount it somewhere on the steering column or rack and diagnostic tools are
needed if it malfunctions.
Figure 4 - Electric Power Steering
EPS is used mainly on hybrid vehicles that try to eliminate pollution such as hydraulic
fluid. These systems, however, are becoming popular as kits for vehicles that never came
with any type of power steering such as Unisteer’s Universal Electra Steer kit.
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UNIVERSAL ELECTRA-STEER Unisteer is a company that sells steering components and kits. Figure 5 (9) shows a
universal electric power steering kit that includes the electric motor, control module, wiring
harness, hardware and a square universal bracket made to be modified as needed. Parts that
are not included in the kit but are available on their website are u-joints, couplers and
steering shafts.
Figure 5 – Universal Electra Steer
As mentioned earlier, Paul Woods put EHPS from a later generation MR2 on his early
generation MR2. He also has successfully put another power steering system on his car by
integrating EPS from another vehicle.
Bracket
Control Module
(ECU)
Steering
Rack
Electric Motor
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ADJUSTABLE POWER STEERING On the website www.imoc.co.uk, there is a forum discussion started by Paul Woods
about his creation of a one-off power steering system for a 1985-89 Toyota MR2 where he
mated Vauxhall Corsa electric power assist parts into the MR2 steering column shown in
Figure 6 and Figure 7 (8). This system uses a custom lower knuckle joint from the column to
the rack. Small modifications needed to be made under the dash to make it fit. He also
installed a knob that allows him to vary the amount of assist and turn it off completely. The
system allows Woods to “park the car with fingertip control even with a stonking V8 and
huge tires.”
Figure 6 - Before Installation
Figure 7 - After Installation
The last type of power steering is Steer-By-Wire but is not fully developed for public roads.
Electric Motor
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STEER-BY-WIRE Steer-By-Wire is basically the same concept as Electronic Power Steering only the
steering column is not connected with the steering rack as seen in Figure 8 (5). On the
steering wheel side is an angle sensor, steering wheel actuator and feedback motor. On the
rack side is the electric motor, pinion and pinion sensor. When the steering wheel is turned,
the actuator tells the electric motor to turn and stops when the pinion angle sensor reads the
same as the steering wheel angle sensor. The feedback motor gives the steering wheel
resistance proportional to the driving conditions. The advantages to Steer- By-Wire are
increased steering smoothness, parking and lane change assist and other vehicle designs. The
disadvantages are much greater cost.
Figure 8 – Steer-By-Wire
The end factor is that, although these Steer-By-Wire systems are on some industrial
vehicles, it is not fully safe for road legal vehicles. The safety redundancies are not fully
developed and if the system were to fail there is no other way of steering.
Based on the research, twelve features from the power steering systems stuck out the
most. The next step is to determine the features order of importance. They are then labeled as
Customer Features and put into a survey to decide the order of importance.
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CUSTOMER FEEDBACK, FEATURES AND OBJECTIVES
SURVEY ANALYSIS The twelve features that are found to be most favored from the research are put into a
survey. The purpose of the survey is to determine the importance of the twelve customer
features that would be designed for in the creation of a power steering system for the 1985-89
Toyota MR2. The ratings are listed from 1-5 with 5 being the most important. It also asks
how much they are willing to pay for such a system by choosing a dollar amount range. The
survey is posted on the Toyota MR2 web forum, http://www.mr2.com, in which there are
fourteen responses. Table 1 shows that after analyzing the results, the importance of each
customer feature are no more than two percent different from the next. The two that tie for
the most important at eleven percent were Durability and Responsive Steering. The three
customer features that tie for least important are Safety, Low Steering Effort and Ease of
Installation. The cost of how much the respondents are willing to pay for the kit comes out to
about $800. (For the complete survey results see Appendix B)
Table 1 – Survey Results
With the customer features defined, Product Objectives are developed as a way to obtain
measurable results.
Customer FeaturesCustomer
Importance
Relative
Weight
Relative
Weight %
Durability 4.00 0.11 11%
Responsive Steering 4.00 0.11 11%
Weight 3.50 0.09 9%
Kit Completeness 3.36 0.09 9%
Ease of Maintenance 3.21 0.09 9%
Compatibility 3.14 0.08 8%
Quiet Operation 2.93 0.08 8%
Low Cost 2.86 0.08 8%
Ease of Installation 2.71 0.07 7%
Low Steering Effort 2.57 0.07 7%
Safety 2.43 0.07 7%
Energy Efficient 2.29 0.06 6%
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PRODUCT FEATURES AND OBJECTIVES The Product Features are the same as the customer features rated on the survey. They are
listed in order of most to least important in accordance with the survey. Under each feature
are Product Objectives. Product Objectives are goals in which to meet the customer features.
The customer features obtained are translated into measurable variables to determine if the
Product Objectives are met.
1. Durability 11%
a. All necessary components will be lubed
b. Materials will be corrosion resistant or painted
2. Responsive Steering 11%
a. Turning ratio will be 18:1 or smaller
3. Kit Completeness 9%
a. Kit will include all hardware
4. Weight 9%
a. Kit will weigh less than 40 lbs.
5. Ease of Maintenance 9%
a. Less than 8 steps
b. Less than 1 hour
6. Low Cost 8%
a. Prototype kit will cost less than $1750
7. Compatibility 8%
a. Will be compatible with a 1985-89 Toyota MR2
8. Quiet Operation 8%
a. Noise of power steering components will not exceed 40 decibels from driver’s
seat
9. Safety 7%
a. Kit will include cautionary notes for installation and maintenance
b. Steering wheel will have a maximum lash of 30mm
10. Low Steering Effort 7%
a. Force required to turn steering wheel will not exceed 15 lbs
11. Ease of Installation 7%
a. Will take less than 8 hours
12. Energy Efficient 6%
a. Will use less than 8% of engine horsepower
After coming up with Product Objectives, the next step is to analyze the importance of
each.
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ENGINEERING CHARACTERISTICS The Product Objectives are then put in a Quality Function Deployment labeled as
Engineering Characteristics and are cross referenced with all the Product Features and
weights to see how important each is to the entire design. They are listed in Table 2 by
percentage in order of higher importance to lower with Materials having the most importance
and Standard Tools Used having the least importance. (For the complete Quality Function
Deployment see Appendix C)
Table 2 – Engineering Characteristics
After the importance of the Product Objectives and Engineering Characteristics are
realized, Design Alternatives and a Selection can be made.
Engineering Characteristics Importance %
Materials 14%
Weight (lbs) 13%
All Hardware Included (Y/N) 13%
Modifications Required (Y/N) 10%
Steps 8%
Time 8%
Standard Parts Used (Y/N) 7%
Steering Ratio 7%
Torque req. to turn wheel (ft*lbs) 6%
Lash (degrees) 5%
Loudness (db) 4%
Manufacturability 4%
Power usage (HP, Volts) 3%
Standard Tools used (Y/N) 3%
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DESIGN ALTERNATIVES AND SELECTION The design alternatives are three of the four types of power steering, which are
Hydraulic, Electro-Hydraulic and Electric. To select to best design, the power steering
systems are rated on how well each would perform in completing the Product Objectives. It
is based on a 0-4 rating system. The power steering system that would perform best receives
a 4 and the others receive a rating relative to it. As shown in the Table 3, the Electric Power
Steering system outperforms or ties Hydraulic and Electro-Hydraulic in every Objective
except for cost, therefore Electric Power Steering is the chosen design.
Table 3 – Design Evaluations
The electric power steering converted column design consists of an upper shaft
assembly, electric motor and lower shaft assembly, shown in Figure 9, located between the
steering wheel and steering rack.
Figure 9 – Column Design
Power Steering
Design Evaluations
Wei
ght
Safety 0.07 3 0.21 3 0.21 4 0.28
Low Cost 0.08 4 0.32 4 0.32 3 0.24
Durability 0.11 3 0.33 3 0.33 4 0.44
Low Steering Effort 0.07 4 0.28 4 0.28 4 0.28
Responsive Steering 0.11 3 0.33 3 0.33 4 0.44
Kit Completeness 0.09 3 0.27 4 0.36 4 0.36
Weight 0.09 3 0.27 2 0.18 4 0.36
Energy Efficient 0.06 1 0.06 3 0.18 4 0.24
Ease of Installation 0.07 1 0.07 3 0.21 4 0.28
Compatibility 0.08 3 0.24 3 0.24 4 0.32
Quiet Operation 0.08 3 0.24 2 0.16 4 0.32
Ease of Maintenance 0.09 2 0.18 2 0.18 4 0.36
1.00 2.80 2.98 3.92
Elec
tric
Elec
tro
-Hyd
rau
lic
Hyd
rau
lic
Upper
Shaft
Assembly
Lower
Shaft
Assembly
Electric
Motor
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LOADING CONDITIONS CALCULATIONS The stress put into the steering system is a torsional force caused by the driver twisting
the steering wheel to get the vehicle to turn and the tires resistance to turn. To find the
maximum turning force, a spring scale is used to turn the steering wheel as shown in Figure
10 (10) below. While the MR2 is parked on a concrete driveway a maximum force of 24 lbf
is applied at a distance of 6.5 inches from the center.
Figure 10 – Steering Effort
The stress concentration area is in the lower shaft assembly and is circled in the solid
model assembly in Figure 11. The electric motor will allow the driver’s input force to the
steering wheel not to exceed 15lbf by adding any additional force that would exceed that
amount. The total force applied through the lower shaft assembly will still be a maximum of
24 lbf. An exploded view in Figure 12 shows that the stress concentration area consists of a
coupler, rod, lower shaft and two pins.
Figure 11 – Solid Model Assembly
Figure 12 – Exploded Stress Area
Coupler
Rod
Lower Shaft
Pins
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The maximum torsional stresses are located at the holes in the parts undergoing
torque. This stress is a result of the gross torsional stress multiplied by a stress concentration
factor. The gross torsional stress is found by using the torque, radius and polar moment of
inertia. The calculations below are for the Rod.
Equation 1 – Gross Torsional Stress
τgross =
=
Before the stress concentration factor can be found the force on the pins must be
known so a hole size can be chosen.
Equation 2 – Force on Pins
The stress concentration factor is found by taking the ratio of the hole diameter over
the Rod diameter and then following the number straight up until it comes to Curve C.
According to Figure 13 (11) a hole from .0625-.125in will provide the same stress
concentration factor.
Figure 13 – Stress Concentration Factor Graph
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Equation 3 – Concentrated Stress Factor
Ktg @ .167 using Curve C = 3.75
The stress concentration factor and gross torsional stress are then multiplied to
produce the maximum torsional stress on the Rod.
Equation 4 – Max Torsional Stress
τmax = Ktg* τgross = 3.75*1.88 ksi = 7.06 ksi
The deflection in the Rod is found using the torque, length, shear stress modulus and
polar moment of inertia.
Equation 5 – Deflection
Θ =
A summary of the results for the component calculations is shown in Table 4. This
shows that the highest design stress is 14.1 ksi and the largest deflection is .0165 degrees in.
(For complete calculations see Appendix E)
Table 4 – Stress Analysis
Stress Analysis
Max
Stress
(ksi)
Safety
Factor
Design
Stress
(ksi)
Deflection
(deg.)
Rod 7.06 2.0 14.1 0.0003
Lower Shaft 4.24 2.0 8.5 0.0165
Coupler 1.50 2.0 3.0 0.0079
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COMPONENT AND MATERIAL SELECTION The electric power steering system chosen is from Easysteer and is adjustable. Its
lowest setting requires and input force of 13.5 lbs. The system comes with many parts as
shown in Figure 14 (12), that allow for the buyer to adapt the system into most vehicles. The
parts list is as follows:
ECU with 2 feet of positive and negative 10 gauge wire
Electric Motor with 2 connectors
Upper steering column with internal splines
Ignition Barrel
Bracket
Universal Joint (not needed)
Control Box with wiring
40 Amp Fuse
7.5 Amp Fuse
Figure 14 - Easysteer
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Since the highest design stress is only 14.1 ksi and the lowest yield strength for a
metal is 30 ksi any metal will suffice for each component. This means the stock column can
be used for the lower shaft. The coupler used has a round 0.75in hole on one side and a 0.75
DD hole on the other shown in Figure – 15 (13).
Figure 15 – Coupler
A .0625in 1070 steel pin, in Table 5 (14), has enough strength for the 416 lbs
of force but a .125in pin is chosen due to its extra strength and availability.
Table 5 – Spring Pins
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The rod in Figure 16 (15) is made from 1018 mild steel with a yield strength of 53.7
ksi.
Figure 16 – Rod
A 2.5in diameter tubing is also needed to replace a smaller diameter portion of the
stock body so piece of 2.5 ID to 2.5OD Aluminized steel tubing, like in Figure 17 (16), is
readily available from the nearest Advanced Auto Parts Store.
Figure 17 – Tube
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FABRICATION AND ASSEMBLY The stock steering column is, first, completely disassembled, as shown in Figure 18.
Figure 18 – Stock Column Disassembled
The body and shaft are both cut, as shown in Figure 19, into three sections; upper,
middle and lower sections. The middle sections are discarded as they are replaced by the
electric motor.
Figure 19 – Cutting the Stock Column
The side of the upper shaft from the MR2 that is cut is then grinded to form the chamfer
shown in Figure 20.
Figure 20 – Cut Upper Shaft
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The splined section of the shaft from Easysteer is cut off and also chamfered and shown
in Figure 21.
Figure 21 – Splined Shaft
After the two parts are machined to a much closer diameter, the chamfered ends of the
splined shaft and the MR2’s upper shaft are butted against each other, clamped between two
v-blocks for concentricity and welded together. The new upper shaft assembly is able to fit
onto the steering wheel side of the electric motor as shown in Figure 22.
Figure 22 – Upper Shaft Assembly
A rod is milled down so half of it fits snuggly inside the lower shaft and the other side
into the DD coupler. A look at the test parts before assembly is shown in Figure 23.
Figure 23 – Lower Shaft Components
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Two holes are drilled and a pin is pressed inside each. One hole is through the lower
shaft and rod and the other is through the coupler and rod so they cannot separate or rotate.
The new lower shaft assembly is fastened onto the rack side of the electric motor as shown in
Figure 24.
Figure 24 – Lower Shaft Assembly
The kit’s flange is cut off from the barrel and bolted down to the steering wheel side of
the electric motor. The upper stock body is bolted to the stock ignition barrel and is placed
over the new upper shaft until it touches the flange. The assembly is then bolted into the
MR2 as a test fit. The electric motor is rotated for best fitment and alignment marks are made
on the upper body and flange as shown in Figure 25. The assembly is then removed and the
upper body and flange are welded together.
Figure 25 – Alignment Marks
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The hole of the bracket from Easysteer is bored out to match the tube and then bolted to
the steering rack side of the electric motor. The tube is inserted over the lower shaft assembly
and into the bracket. The lower body is bolted over the lower shaft assembly. The assembled
column is laid upside down with the flat part of the upper body and the flat part of the lower
body that gets bolted to the car rest on blocks as shown in Figure 26. The tube is tack welded
to the bracket and lower body then is removed from the rest of the column and is welded the
rest of the way around.
Figure 26 – Upper and Lower Body Alignment
The completed electric power steering column can be seen in Figure 27 and Figure 28.
Figure 27 – Power Steering Column Disassembled
Figure 28 – Power Steering Column Assembled
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24
A hole is drilled in the lower dash panel for the adjustment knob and a portion of the
lower dash panel is cut where the electric motor interferes with it. The results are shown in
Figure 29.
Figure 29 – Knob Location
The ECU is installed behind the radio. The connectors from the electric motor and
control box are plugged into the ECU and the positive and negative 10 gauge wires are ran
from the ECU, under the carpet, through the firewall and to the battery. The column, dash
panel and steering wheel are then installed, as shown in Figure 30, and the MR2 is ready for
testing.
Figure 30 – Power Steering Column Installed
Adjustment
Knob
Cut-out
1985-89 MR2 POWER STEERING ADAM CLOSE
25
TESTING AND PROOF OF DESIGN The electric power steering system is tested to make sure each Product Objective is met.
The Power Steering System needs to be Lubed and Corrosion resistant and they are. The
column is inside the vehicle and will come in very little contact with moisture. The turning
ratio is to be 18:1 or smaller. This is measured with a protractor by dividing the change in
degrees of the steering wheel to the wheels which is a ratio of 18:1 and is unchanged.
The kit is to include all hardware to bolt the Power Steering System directly to the MR2’s
chassis and function and it does. Using a scale it weighs only 16 lbs which is less than the 40
lb maximum. The system’s maintenance is not to exceed eight steps and one hour. By using
an electric system it does not require any maintenance. The system is to be compatible with
the 1985-89 Toyota MR2 and it is. It bolts directly to the chassis in place of the old manual
column. The prototype cost $938 which is less than the forecasted amount of $1725 and that
includes all components and machining labor. The system is not to exceed a decibel reading
of 40 which is very noticeable to the human ear. During testing it makes no audible sound so
the use of a decibel meter is deemed unnecessary. Using a ruler the steering wheel lash
measures less than the 30mm limit at 23mm. The input steering effort required by the driver
does not to exceed the 15 lbs limit. With the adjustment knob set on the high setting, the
input effort does not exceed 7 lbs of force and with it set to its low setting the input effort
does not exceed 13.5 lbs of force. The installation time only takes about 4 out of the 8 hours
mainly due to running the battery wires under the carpet and back to the engine bay.
The electric motor uses a maximum horse power draw from the alternator of 0.410 HP and is
only 0.459% of the engines horsepower which is less than the 8.0% maximum.
Figure 31 – Effort of 7 lbs
1985-89 MR2 POWER STEERING ADAM CLOSE
26
SCHEDULE AND BUDGET
SCHEDULE The schedule measures 24 weeks long. It starts with the Proof of Design phase on
October 14th
and ends with the Final Project Report on April 15th
. Between these dates Table
3 shows the proposed and actual schedule of designing, modeling, bill of materials, ordering,
assembly and testing. The actual schedule took a few weeks longer but everything was
completed in time for the Tech Expo. (For the complete Schedule see Appendix E)
Table 6 – Schedule
TASKS
Analysis and Design of Steering Column
Analysis and Design of Pump
CAD Models
Bill of materials
Order parts
Assembly and Testing
Proposed
Actual
AprilNovember December Jan February March
Adam Close1985-89 MR2 Power Steering
1985-89 MR2 POWER STEERING ADAM CLOSE
27
BUDGET The budget is a list of every expense that is involved with the project. This includes
components and labor for machining. The total cost to fit the power steering to the car was
estimated to be about $1750 but ended up only costing $938.
Table 7 – Budget
Components Forcasted Cost Actual Cost
Pump 500.00$
Wiring, Relays,Fuses, etc. 50.00$
Computer 200.00$
Brackets 25.00$
Intermediate Shaft 75.00$
Universal Joint 75.00$
Steering Rack 500.00$ -
Fluid 50.00$ -
Fluid Reservior 100.00$ -
Pressure Lines 150.00$ -
DD Coupler - 19.49$
Pipe - 2.5" x 18" LG - 13.95$
Machining, welding,
rod, pins-
$375.00
TOTAL 1,725.00$ 938.44$
BUDGET
530.00$
1985-89 MR2 POWER STEERING ADAM CLOSE
28
RECOMMENDATIONS The electric motor chosen for this project is both large and much more powerful than is
needed for the MR2 but was chosen mostly due to the low price. The use of a smaller motor
would benefit by freeing up space for a heating and cooling duct alternative and also to
regain full range for the column to tilt. With the assist turned on high the driver only needs 7
lbf maximum to steer. At this level, the vehicle was very easy to turn but at speeds up to 35
mph it felt dangerous. The vehicle has not been driven at highway speeds at this level but is
highly recommended not be done. With the assist turned to low the driver needs a maximum
input force of 13.5 lbf and feels very comfortable but 15 lbf might be perfect. Therefore an
electric motor at half the capacity would be ideal.
1985-89 MR2 POWER STEERING ADAM CLOSE
29
WORKS CITED 1. Walker, Paula. Hamilton, September 9, 2012.
2. Walker, Jen. Cincinnati, September 9, 2012.
3. Close, Joyce. Cincinnati, September 9, 2012.
4. Close, Dan. Cincinnati, September 9, 2012.
5. Sclar, Deanna. Auto Repair for Dummies. Indianapolis : Wiley Publishing, Inc., 2009.
ISBN: 978-0-7645-9902-6.
6. 1965-70 Flaming River Power Steering Rack With Tilt Column. www.mustangplus.com.
[Online] [Cited: September 20, 2012.] http://www.mustangsplus.com/xcart/1965-70-
Flaming-River-Power-Steering-Rack-With-Tilt-Column.html.
7. Motoring News. www.webwombat.com. [Online] August 5, 2010. [Cited: October 17,
2012.] http://www.webwombat.com.au/motoring/news/news0028.htm.
8. Adjustable Power Steering. International MR2 Owners Club. [Online] [Cited: September
8, 2012.]
http://www.imoc.co.uk/forums/viewtopic.php?t=134255&postdays=0&postorder=asc&start=
0.
9. Universal Electra-Steer. www.unisteer.com. [Online] [Cited: September 8, 2012.]
http://www.unisteer.com/search_by_product/electric_power_steering/electra-steer.html.
10. Stationary Steering Force. Out-Club. [Online] [Cited: December 16, 2012.] http://faq.out-
club.ru/download/outlander-
III/maintenance/Service_Manual_2013/2013/37/html/M137200170120500ENG.HTM.
11. Mott, Robert L. Machine Elements in Mechanical Design. 4th. Upper Saddle River :
Pearson Prentice Hall, 2004. ISBN 0-13-061885.
12. Electric Power Steering Kit. Photobucket.com. [Online] mk2mania. [Cited: December 20,
2012.]
http://s187.photobucket.com/user/mk2mania/library/electric%20power%20steering%20kit?s
ort=3&page=1.
13. Borgeson 315249 3/4" DD x 1" DD Steel Steering Coupler. Sears.com. [Online] [Cited:
December 22, 2012.] http://www.sears.com/borgeson-315249-3-4inch-dd-x-1inch-dd-steel/p-
SPM6384329308?prdNo=7.
14. PinsRollSpring. fastenersuperstore.com. [Online] [Cited: December 28, 2012.]
http://www.fastenersuperstore.com/productSheets/PinsRollSpring.pdf.
15. 1018-steel-round-rod-750-diameter-x-48-long. onlinemetalsupply.com. [Online] [Cited:
December 28, 2012.] http://www.onlinemetalsupply.com/steel/steel-round-rod/1018-steel-
round-rod-750-diameter-x-48-long.html.
16. 3A-Racing-3-in-i-d-x-18-in-length-tailpipe-extension. autozone.com. [Online] [Cited:
December 16, 2012.] http://www.autozone.com/autozone/accessories/3A-Racing-3-in-i-d-x-
18-in-length-tailpipe-extension/_/N-257z?itemIdentifier=258995&_requestid=315229.
Appendix A1
APPENDIX A - RESEARCH
Interview with daily commuter, September 9, 2012
Paula Walker of 735 Gordon Smith Blvd, Hamilton, Ohio 45013
Use to drive a 1956 Buick Special that had a semi truck size steering wheel and no
power steering.
Feels that non-power steering is not difficult on city streets except when parallel
parking.
Says vehicles with power steering are much easier to drive all-around.
Prefers modern size steering wheel and power steering.
Interview with daily commuter, September 9, 2012
Joyce Close of 767 West Pekin Road, Lebanon, Ohio 45036
Has driven a 1995 Ford Van and a 2000 Ford 350 Truck in which both power steering
systems developed play. Wants reliable power steering.
Interview with daily commuter and racecar driver, September 9, 2012
Dan Close of 767 West Pekin Road, Lebanon, Ohio 45036
Prefers daily driver to have low steering effort and racecar to have responsive steering.
Interview with daily commuter, September 9, 2012
Jen Walker of 8421 Haskell Road, Cincinnati, Ohio 45239
Likes power steering with responsive handling.
Appendix A2
Universal Electra-Steer
If you have ever dreamed of having the ability to allow your engine
more horsepower at the flick of a switch or ease the pain of
maneuvering a tough spot at the local cruise night then you need to
check out Electra-Steer by Unisteer. Electra-Steer is a compact
electric power assist unit that decreases steering effort up to 35%
compared to manual steering. They work off of the vehicles already
existing 12 volt system without any modifications and go right in
line with your steering shaft. The vehicle must use a steering wheel
and not exceed a total weight of 3,000 lbs.
Universal kit includes:
Electric motor
Control module
Wiring harness
Square universal mount bracket
Hardware
Universal kit does not include
U-joints
Couplers
Steering shaft
Universal
Compact
Can be turned off
Does not use
horsepower
Does not come
with everything
needed
Cost $995.00
http://www.unisteer.com/se
arch_by_product/electric_p
ower_steering/electra-
steer.html 9/8/12
Universal Electra-Steer
www.unisteer.com
Appendix A3
Adjustable Power Steering
Forum discussion started by Paul Woods about his creation of a
one-off power steering system for a 1985-89 Toyota MR2
mating Vauxhall Corsa electric power assist parts into the MR2
steering column.
Uses a custom lower knuckle joint from column to rack.
Slight alterations under the dash need to be made for fitment.
Can be turned off or vary the amount of assist with knob he
installed on the dash.
Can park the car with fingertip control even with a V8 and wide
tires.
Variable amount of
assist
Fingertip Control
Unknown cost of parts
Not all parts used are
known
Not a kit
http://www.imoc.co.uk/foru
ms/viewtopic.php?t=134255
&postdays=0&postorder=asc
&start=0 9/8/12 Adjustable
Power Steering
www.imoc.co.uk
Appendix A4
MK2 Powered MK1 MR2
In a forum discussion where Paul Woods incorporates Corsa
power assisted steering into a 1985-89 Toyota MR2 steering
column he mentions, “A few years ago I retro fitted a Mk2
PAS system onto a Mk1 using a USDM rack, turned upside
down, and then fitted all of the Mk2 pump and control
system, it worked but it was heavy and made the Mk1 feel
funny to steer. There was no adjustability in that setup at
all.” Mk1 refers to a 1985-89 MR2 and an Mk2 is a 1991-98
MR2. PAS stands for Power Assisted Steering.
Used parts from later
model
Parts too heavy
Made steering feel funny
http://www.imoc.co.uk/forums/vie
wtopic.php?t=134255&postdays=0
&postorder=asc&start=0 9/8/12
Adjustable Power Steering www.imoc.co.uk
Appendix A5
Flaming River Power Steering Rack With Tilt Column
Add power steering to your classic Mustang. These Flaming
River 1965-70 Mustang power rack and pinion conversion kits
are designed to give you driving comfort, especially when
parking. They feature a cradle that mounts in the original
chassis location with no modification, and the center support
does not have to be removed. The kits include: a new tilt
steering column with universal joints, shafting, support bearing,
billet aluminum reservoir, power rack and pinion, and mounting
cradle. They also include all grade 8 mounting hardware and a
variable pressure pump for true-steering driving performance.
Kit is complete
Easy to park
No modifications to
intended vehicle
Cost $1,999.95
http://www.mustangsplus.com/xcart/1965-
70-Flaming-River-Power-Steering-Rack-
With-Tilt-Column.html 9/20/2012 1965-70
Flaming River Power Steering Rack With
Tilt Column
www.mustangplus.com
Appendix A6
Slightly less compact
than non-powered
steering rack
Would decrease fuel
economy by using
the motor to power
the pump
Auto Repair for Dummies,
(2009) pg. 296
Appendix A7
Electro-Hydraulic Power Steering For the first time in the world, an Electro-hydraulic Power Steering
system has been adopted in which the motor is activated only when
the driver is steering. The system is smaller than traditional power
steering systems, which was achieved by integrating multiple parts.
It offers the advantages of both types of steering - the natural and
smooth steering of hydraulic power steering and the improved fuel
efficiency of electric power steering - combined to create a balanced
system fitting the Nissan Fuga and Infiniti M’s luxury sport sedan
buyers’ needs.
Natural and
smooth steering
Smaller than
Hydraulic Power
Steering
Improved fuel
efficiency
Leaks
Requires routine
maintenance.
http://www.webwombat.com.au/mot
oring/news/news0028.htm
10/17/2012 Motoring News
www.webwombat.com
Appendix A8
No modification to
steering rack
Compactness
depends on of size of
motor
Electric motors have
a moderate to high
cost
Auto Repair for Dummies,
(2009) pg. 297
Appendix A9
Light weight
Steers smoothly
Reduces chance of
mechanical failure
Will not decrease fuel
economy
Very high cost
Not completely
reliable or safe on road
vehicles yet
Auto Repair for Dummies,
(2009) pg. 299
Appendix B1
APPENDIX B - SURVEY
POWER STEERING FOR 1985-89 MR2
CUSTOMER SURVEY
The purpose of this survey is to determine the importance of each feature that will be
designed for in the creation of a power steering system for the 1985-89 Toyota MR2.
How important is each feature to you for the design of a power steering system?
Please circle the appropriate answer. 1 = low importance 5 = high importance
Avg.
Safety 1(4) 2(2) 3(2) 4(5) 5 N/A(1) 2.43
Low cost 1(3) 2(2) 3(1) 4(5) 5(2) N/A(1) 2.86
Durability 1(2) 2 3(1) 4(4) 5(7) N/A 4.00
Low steering effort 1(6) 2(1) 3(1) 4(5) 5(1) N/A 2.57
Responsive steering 1(3) 2 3 4(2) 5(9) N/A 4.00
Kit Completeness 1(3) 2 3(1) 4(4) 5(5) N/A(1) 3.36
Weight 1(3) 2(3) 3(2) 4(1) 5(6) N/A 3.50
Energy efficient 1(5) 2(2) 3(2) 4(3) 5(1) N/A(1) 2.29
Ease of installation 1(3) 2(1) 3(4) 4(4) 5(1) N/A(1) 2.71
Compatibility 1(3) 2(1) 3(1) 4(4) 5(4) N/A(1) 3.14
Quiet operation 1(3) 2(2) 3(2) 4(2) 5(4) N/A(1) 2.93
Ease of Maintenance 1(3) 2 3(2) 4(4) 5(4) N/A(1) 3.21
37.0
How much would you be willing to pay for a product like this?
Avg.
$100-$200(5) $200-$500(5) $500-$1000(2) $1000-$2000 $2000-$5000(1) $800
Thank you for your time.
Appendix C1
APPENDIX C – PRODUCT OBJECTIVES Product Objectives are goals in which to meet the customer requirements. The customer requirements
obtained are translated into measurable variables which determine if the Product Objectives are met.
1. Durability 11%
a. All necessary components will be lubed
b. Materials will be corrosion resistant or painted
2. Responsive Steering 11%
a. Turning ratio will be 18:1 or smaller
3. Kit Completeness 9%
a. Kit will include all hardware
4. Weight 9%
a. Kit will weigh less than 40 lbs.
5. Ease of Maintenance 9%
a. Less than 8 steps
b. Less than 1 hour
6. Low Cost 8%
a. Prototype kit will cost less than $1750
7. Compatibility 8%
a. Will be compatible with a 1985-89 Toyota MR2
8. Quiet Operation 8%
a. Noise of power steering components will not exceed 40 decibels from driver’s
seat
9. Safety 7%
a. Kit will include cautionary notes for installation and maintenance
b. Steering wheel will have a maximum lash of 30mm
10. Low Steering Effort 7%
a. Force required to turn steering wheel will not exceed 15 lbs
11. Ease of Installation 7%
a. Will take less than 8 hours
12. Energy Efficient 6%
a. Will use less than 8% of engine horsepower
Appendix D1
APPENDIX D – QUALITY FUNCTION DEPLOYMENT
Lash (
degre
es)
Sta
ndard
Part
s u
sed (
Y/N
)
Weig
ht
(lbs)
Torq
ue r
eq.
to t
urn
wheel (f
t*lb
s)
Turn
ing R
atio (
ratio o
f deg.)
All
Hard
ware
inclu
ded (
Y/N
)
Mate
rials
Manufa
ctu
rabili
ty
Pow
er
usage (
HP
, V
olts)
Ste
ps (
#)
Tim
e (
hrs
.)
Sta
ndard
Tools
used (
Y/N
)
Modific
ations R
eq.
(Y/N
)
Loudness (
db)
Custo
mer
import
ance
Rela
tive w
eig
ht
Rela
tive w
eig
ht
%
Safety 9 1 3 1 2.43 0.07 7%
Low Cost 9 3 9 9 9 2.86 0.08 8%
Durability 3 9 4.00 0.11 11%
Low Steering Effort 1 9 3 2.57 0.07 7%
Responsive Steering 3 3 3 9 4.00 0.11 11%
Kit Completeness 9 1 3.36 0.09 9%
Weight 9 9 3.50 0.09 9%
Energy Efficient 9 2.29 0.06 6%
Ease of Installation 3 9 9 9 9 3 9 2.71 0.07 7%
Compatibility 1 1 9 3.14 0.08 8%
Quiet Operation 9 2.93 0.08 8%
Ease of Maintenance 1 9 9 3 3 3.21 0.09 9%
Abs. importance 0.92 1.32 2.29 1.15 1.25 2.26 2.52 0.70 0.56 1.44 1.44 0.48 1.77 0.71 17.88 37.0 1.0 1.0
Rel. importance 0.05 0.07 0.13 0.06 0.07 0.13 0.14 0.04 0.03 0.08 0.08 0.03 0.10 0.04 1.00
Adam Close
1985-1989 MR2 PowerSteering Kit
9 = Strong3 = Moderate1 = Weak
Appendix E1
APPENDIX E – CALCULATIONS
ROD
Torsional Stress
τmax =
=
Deflection
Θ =
Torsional stress at hole
Ktg @ .167 = 3.75
τmax = Ktg* τgross = 3.75*1.88 ksi = 7.06 ksi
LOWER SHAFT
Torsional Stress
τmax =
=
Appendix E2
Deflection
Θ =
Torsional stress at hole
Ktg @ .125 = 3.65
τmax = Ktg* τgross = 3.65*1.162 ksi = 4.24 ksi
COUPLER
Torsional Stress
τmax =
=
Deflection
Θ =
Torsional stress at hole
Ktg @ .1 = 3.20
τmax = Ktg* τgross = 3.20*.467 ksi = 1.50 ksi
FORCE ON PINS
Appendix E3
POWER STEERING MOTOR
Horsepower usage from power steering
Percentage of Engine Horsepower
Appendix F1
APPENDIX F – SCHEDULE
TASKS Oct
14
-20
Oct
21
-27
Oct
28
- N
ov
3
No
v 4
- 1
0
No
v 1
1 -
17
No
v 1
8 -
24
No
v 2
5 -
Dec
1
Dec
2 -
8
Dec
9 -
15
Dec
16
- 2
2
Dec
23
- 2
9
Dec
30
- J
an 5
Jan
6 -
12
Jan
13
- 1
9
Jan
20
- 2
6
Jan
27
- F
eb 2
Feb
3 -
9
Feb
10
- 1
6
Feb
17
- 2
3
Feb
24
- M
ar 2
Mar
3 -
9
Mar
10
- 1
6
Mar
17
- 2
3
Mar
24
- 3
0
Mar
31
- A
pr
6
Ap
r 7
- 1
3
Ap
r 1
4 -
20
Ap
r 2
1 -
27
Proof of Design to advisor 22
22
Concept sketches to advisor 22
22
Report 29
29
Analysis and Design of Steering Column 5
15
Model Steering Column 12
15
Analysis and Design of Motor 19
15
Model Motor 26
15
Design Freeze 15
15
Bill of materials 15
15
Order parts 15
3
Oral Report 13
13
Design Report to Advisor 13
13
Assembly and Testing 24
24
Demo to Advisor 25
Expo 4
4
Final Oral Report 16
16
Project Report 21
21
Adam Close1985-89 MR2 Power Steering
Appendix G1
APPENDIX G - BUDGET
Components Forcasted Cost Actual Cost
Pump 500.00$
Wiring, Relays,Fuses, etc. 50.00$
Computer 200.00$
Brackets 25.00$
Intermediate Shaft 75.00$
Universal Joint 75.00$
Steering Rack 500.00$ -
Fluid 50.00$ -
Fluid Reservior 100.00$ -
Pressure Lines 150.00$ -
DD Coupler - 19.00$
Pipe - 2.5" x 18" LG - 14.00$
Machining, welding, rod,
pins-
$375.00
TOTAL 1,725.00$ 938.00$
BUDGET
530.00$
Appendix H1
APPENDIX H – DRAWINGS
Appendix H2
Appendix H3
Appendix H4
Appendix H5
Appendix H6
Appendix H7
Appendix H8
Appendix H9
Appendix H10
Appendix H11
Appendix H12
Appendix H13
Appendix H14
Appendix H15
Appendix I1
APPENDIX I – PRESENTATION
By Adam Close Advisor: Prof. Dave
Appendix I2
Problem Definition and Background
1985-89 MR2
Small 2-seater = Great Commuter
No power steering = Difficult to maneuver at low speeds and take slightly longer to park
I will enable the MR2 to be parked using one hand
Appendix I3
Four Types of Power Steering
Hydraulic
Electro-Hydraulic
Electric
Steer-by-Wire
Appendix I4
Hydraulic Power SteeringEngine driven hydraulic pump Most common
Least compact
Decreases fuel economy and horsepower
Leaks over time
Requires routine maintenance
Appendix I5
Electro-Hydraulic Power Steering Electric motor driven
pumpMostly on mid-engine
vehicles
Smaller than hydraulic
Leaks over time
Requires routine maintenance.
Appendix I6
Electric Power SteeringElectric motor integrated into the
steering columnHybrid vehicles
Very Compact
No leaks
No maintenance
Appendix I7
Steer-By-Wire Electric motors on steering wheel
side and rack side
No physical link
Angle sensors
Feedback sensor
Boats and forklifts
Very Compact
Reduces chance of mechanical failure
Very high cost
Not completely reliable or safe on road vehicles yet
Appendix I8
Survey Analysis Twelve features
from interviews and types of P/S
Posted on car forum mr2.com
Fourteen responses
Average willing to pay $800 for a kit
Customer FeaturesCustomer
Importance
Relative
Weight
Relative
Weight %
Durability 4.00 0.11 11%
Responsive Steering 4.00 0.11 11%
Weight 3.50 0.09 9%
Kit Completeness 3.36 0.09 9%
Ease of Maintenance 3.21 0.09 9%
Compatibility 3.14 0.08 8%
Quiet Operation 2.93 0.08 8%
Low Cost 2.86 0.08 8%
Ease of Installation 2.71 0.07 7%
Low Steering Effort 2.57 0.07 7%
Safety 2.43 0.07 7%
Energy Efficient 2.29 0.06 6%
Appendix I9
Measureable Objectives
Weigh less than 40 lbs.
Cost less than $1725 to produce prototype
Not exceed 40 decibels from driver’s seat
Steering wheel will have a maximum lash of 30 mm
Steering effort will not exceed 15 lbs
Use less than 8% of engine horsepower
Appendix I10
Engineering Characteristics
Importance determined using House of Quality
Each Engineering Characteristic rated in importance against each feature (if applied) with a 1, 3 or 9 with 9 being the highest
Total of 100%
Engineering Characteristics Importance %
Materials 14%
Weight (lbs) 13%
All Hardware Included (Y/N) 13%
Modifications Required (Y/N) 10%
Steps 8%
Time 8%
Standard Parts Used (Y/N) 7%
Steering Ratio 7%
Torque req. to turn wheel (in*lbs) 6%
Lash (mm) 5%
Loudness (db) 4%
Manufacturability 4%
Horsepower usage 3%
Standard Tools used (Y/N) 3%
Appendix I11
Selection Process Determined which
power steering type performed best with the Objectives
Based on 0-4 rating system with 4 being best
Scores are relative to each other
Electric wins all but cost
Power Steering
Design Evaluations
Wei
ght
Safety 0.07 3 0.21 3 0.21 4 0.28
Low Cost 0.08 4 0.32 4 0.32 3 0.24
Durability 0.11 3 0.33 3 0.33 4 0.44
Low Steering Effort 0.07 4 0.28 4 0.28 4 0.28
Responsive Steering 0.11 3 0.33 3 0.33 4 0.44
Kit Completeness 0.09 3 0.27 4 0.36 4 0.36
Weight 0.09 3 0.27 2 0.18 4 0.36
Energy Efficient 0.06 1 0.06 3 0.18 4 0.24
Ease of Installation 0.07 1 0.07 3 0.21 4 0.28
Compatibility 0.08 3 0.24 3 0.24 4 0.32
Quiet Operation 0.08 3 0.24 2 0.16 4 0.32
Ease of Maintenance 0.09 2 0.18 2 0.18 4 0.36
1.00 2.80 2.98 3.92
Elec
tric
Elec
tro
-Hyd
rau
lic
Hyd
rau
lic
Appendix I12
Electric Power Steering Products Available
Flaming River
Unisteer
Easysteer
All products come with Motor, CPU, most wiring.
Appendix I13
Flaming RiverPros
Input effort = 13.5 lbs
Adjustable Assist
90 Day Warranty
Cons
$5950.00 + Shipping
Large motor
Appendix I14
UnisteerPros
Lifetime Warranty
$995 + Shipping
Cons
Assist not adjustable
Input effort = 15.6 lbs
Appendix I15
EasysteerPROS
Input effort = 13.5 lbs
Adjustable Assist
Lifetime Warranty
$400.00 + Shipping
CONS
Large motor
Appendix I16
Loading Conditions
24 lbs Max@ 6.5 in
Appendix I17
Loading ConditionsSteering wheel side
Rack side
Power Steering Motor
Concentrated stress area
Appendix I18
Solid Model Exploded Assembly
CouplerRod
Lower Shaft
Pins
Appendix I19
Equations for Torsional Stress
Appendix I20
Sample CalculationsROD Torsional Stress = = 24 6.5 = 156
=
2=
.75
2= .375
=
32 4 =
32 (.75 )4 = .0311 4
τmax =
=
156 .375
.0311 4 = 1.88
Deflection
Θ = 𝐿
𝐺 =
156 .75
11.5 106 / 2 .0311 4
180
= .000327
Appendix I21
Method for Stress Around Holes
Appendix I22
Sample Calculations
Torsional stress at hole
= .
125
. 75= .167
Ktg @ .167 = 3.75 τmax = Ktg* τgross = 3.75*1.88 ksi = 7.06 ksi
Appendix I23
Stress Table
Stress AnalysisMax Stress
(ksi)
Yield
Strength (ksi)
Safety
Factor
(>2.0)
Deflection
(deg.)
Rod - 1018 Mild Steel 7.06 53.7 7.6 0.0003
Lower Shaft - (assuming
1020 Hot-rolled steel)4.24 30.0 7.1 0.0165
Coupler - (assuming 1020
Hot-rolled steel)1.50 30.0 20.1 0.0079
Appendix I24
Sample Calculations
FORCE ON PINS
=
=
156
. 75 = 208
Stress AnalysisMax Force
(lbs)
Yield
Strength (lbs)
Safety
Factor
Spring Pin
(Carbon Steel, 1/8 in)208 1875 9.0
Appendix I25
Component and Material Selection
DD Coupler
Rod
Spring Pins
Appendix I26
DD Coupler Borgeson Universal
Steering Shaft Coupler
Steel, 3/4 in DD, 3/4 in
Cost $19.49
Appendix I27
Rod Dreier Tool & Die Corp.
1018 Mild Steel, ¾ in. Diameter, 2 in. Long
Free with machining service
Appendix I28
Spring Pins Dreier Tool & Die Corp.
Carbon Steel, 1/8 in. Diameter, 2 in. Long
Free with machining service
Appendix I29
Planned Fabrication & AssemblyUpper column to power steering motor:
Butted upper column to spline shaft
Welded between two V-blocks for concentricity
Mounted onto power steering motor
Appendix I30
Planned Fabrication & AssemblyPower steering motor to lower column:
Attached coupler to power steering motor
Inserted ¾ in. rod into coupler
Placed lower column over rod against coupler
Drilled 1/8 in. hole through coupler and rod
Inserted 1/8 in. pin
Drilled 1/8 in. hole through lower column and rod
Inserted 1/8 in. pin
Appendix I31
Testing & Proof of Design
Objective Test Method Results Pass/Fail Importance
Lubed and Corrosion resistant Visual Yes Pass 11%
Turning Ratio 18:1 or smaller Protractor 18:1 Pass 11%
Kit includes all hardware Visual Yes Pass 9%
Weighs less than 40 lbs Weight Scale 16 lbs Pass 9%
Maintenance less than 8 steps, 1 hour Clock 0 steps, 0 hours Pass 9%
Costs less than $1725 to make Calculator $938 Pass 8%
Compatible with 1985-89 MR2 Visual Yes - 8%
Does not exceed 40 decibels Decibel Meter 0 Pass 8%
Steering wheel will have a maximum lash
of 30 mmRuler 23 mm Pass 7%
Steering effort does not exceed 15 lbs Fish Scale 7 lbs Pass 7%
Installation should take less than 8 hours Clock 4 hours Pass 7%
Use less than 8% of engine horsepower Engine Dyno 0 hp Pass 6%
Appendix I32
Compatibility
New power steering column bolts directly to frame in place of old one but due to the large motor:
Tilt is decreased by 50%
One of the heating and cooling ducts has to be removed with no room for a replacement
Dash panel needs a portion cut out
Appendix I33
Recommendations
A smaller power steering motor could allow:
full tilt
flexible replacement for heating and cooling duct
Possibly an uncut dash panel
Appendix I34
Schedule Discussion (Proposed/Actual)
TASKS
Analysis and Design of Steering Column
Analysis and Design of Pump
CAD Models
Bill of materials
Order parts
Assembly and Testing
Proposed
Actual
November December Jan February March
Adam Close1985-89 MR2 Power Steering
Appendix I35
Budget
Components Forcasted Cost Actual Cost
Pump 500.00$
Wiring, Relays,Fuses, etc. 50.00$
Computer 200.00$
Brackets 25.00$
Intermediate Shaft 75.00$
Universal Joint 75.00$
Steering Rack 500.00$ -
Fluid 50.00$ -
Fluid Reservior 100.00$ -
Pressure Lines 150.00$ -
DD Coupler - 19.49$
Pipe - 2.5" x 18" LG - 13.95$
Machining, welding,
rod, pins-
$375.00
TOTAL 1,725.00$ 938.44$
BUDGET
530.00$
Appendix I36
Questions?
Appendix J1
APPENDIX J – WIRING DIAGRAM
ECU
Electric
Motor
Control
Box
Adjustable
Knob
7.5 Amp
Fuse
40 Amp
Fuse
Battery
Ground
12v
(radio acc)
Multiple Wires with Connecter
10 Gauge Positive
10 Gauge Negative
18 Gauge Positive
18 Gauge Negative
Appendix K1
APPENDIX K – WIRE ROUTING