Go-Kart's Design And Construction

Based On Theoretical And Experimental Findings

By

Ho Yoong Chow

Thesis submitted to the Faculty of Engineering,

Universiti Malaysia Sarawak

As a partial fulfillment of the requirement for the Degree of Bachelor of Engineering with Honours

(Mechanical Engineering and Manufacturing System)

2001

Acknowledgements

I would like to express my deepest appreciation for those who helped me in

making this paper such a success. Without their support and assistance, this

paper would not be completed as it is and in such short term.

First and foremost, I would like to thank my supervisor, Mr. Syed Tarmizi

Syed Shazali, who had provided me a truly understanding of scholarship and

support along this paper.

Next, my fellow group mates, Mr. Tan Tang Chin, Mr. Fam Kueh Szue,

and Mr. Rowdy Ignatius, who have been very cooperative and supportive to rne.

I would like to say thank to our CNC laboratory technician, Mr. Masri b.

Zaini and Mr. Rhyier a/k Juen, who supplement me the skill of operating and

handling the machine, tools and devices.

By this opportunity, I would also like to thank Mr. Opec Kadri, owner and

Managing Director of Cosama Sdn Bhd, and Mr. Wan Azlan Shah, lecturer of

Polytechnic Kuching, who generously provided me with knowledge for building a

go-kart.

Finally, I would also like to thank my family, fellow friends and those

involved in completion of this project and documentation.

Ho Yoong Chow

UNIMAS, 2001

iv

Table Of Contents

Letter of Approval

Approval Sheet

Project Title

Acknowledgements

Table of Contents

List of Figures

List of Tables

List of Graph

Abstract

Abstrak

1 Introduction

1.1 History of Go-Kart

1.2 Go-Kart Today and Future

2 Literature Review

2.1 Introduction

2.2 Chassis Design

2.2.1 Frame Construction

2.2.2 Unit-Body Construction

2.2.3 Space Frame Construction

2.3 Platform

2.4 Chassis Materials

2.4.1 Galvanized Steel

2.4.2 High-Strength Steel

2.4.3 Chrome-moly

2.5 Evaluating Go-Kart's Chassis

2.5.1 Chassis Squareness

2.5.2 Length

Pages

i.

ii.

iii.

iv.

V.

viii.

X.

XI.

XI1.

1

1

2

4

4

4

5

7

8

8

9

10

10

11

11

11

12

V

2.5.3 Steering Position Alignment

2.5.4 Kart Straightness

2.5.5 Other Jobs

2.6 Basic Go-kart's Chassis Theories

2.6.1 Frame Construction

2.6.2 Side Bite

2.6.3 Torsion Bars

2.6.4 Ackerman Steering

2.6.5 Kingpin Inclination

2.6.6 Spindle

2.6.7 Scrub Radius

2.6.8 Caster

2.6.9 Caster Stagger

2.6.10 Camber

2.6.11 Toe-in

3 Methodology

3.1 Data Collection From Research

3.2 Data Collection From Interview

3.3 Mathematical Analysis

3.4 Chassis Design Generation

3.5 Go-Kart Construction

3.6 Initial Chassis Setup

3.6.1 Chassis Baseline

3.6.2 Chassis Alignment

3.6.3 Initial Setup

3.6.4 Rear Axle

3.6.5 Rear Axle Mounting

3.6.6 Spindle Installation

3.6.7 Front And Side Bumper

3.6.8 Seat Installation

3.6.9 Floor Pan

vi

3.6.10 Weight Distribution 4 *1 3.7 Chassis Material Testing 45

3.8 Evaluation Of The Final Product 47

4 Results And Discussions 48

4.1 Frame Design 48

4.2 Chassis Baseline Measurements 49

4.3 Kingpin Inclination of Chassis 53

4.4 Spindle Angle 53

4.5 Scrub Radius 54

4.6 Caster Setting 55

4.7 Caster Stagger 56

4.8 Camber 56

4.9 Weight Distribution 57

4.10 17 Degree Method 59

4.11 Chassis Material Evaluation 60

4.12 Photo Gallery 65

5 Conclusion And Recommendations 71

References 74

Appendices

A-1 Sample Go-Kart Chassis From Specter Racing Chassis

A-2 Sample Technical Drawing

A-3 Go-Kart build by students of Polytechnic Kuching

A-4 Go-karts found in Cosama Sdn. Bhd.

A-5 Kart Setup Output

A-6 Tensile Properties For Some Engineering Metals:

Engineering Properties.

A-7 Technical Drawings of MechTech-Initial

vii

List Of Figures

Pages

1.1 One of karting pioneer, Don Boberick riding the first 2 Rathmann Xterminator prototype kart. (Extracted from

http: //www. vintagekarts. com) 1.2 Don driving the "Drone" at the Rose Bowl parking lot 1957.2

(Extracted from http: //www. vintagekarts. com) 2.1 Ladder frame of a common vehicle. (Extracted from 5

Automotive Chassis Systems, p. 2)

2.2 Perimeter frame of a common vehicle. (Extracted from 6

Automotive Chassis Systems, p. 2)

2.3 (a) Unitized construction, the small frame members are for 7

support of he engine and suspension components. Many

vehicle would attached the suspension components directly

to the reinforced sections of the body and do not required

the rear frame section; (b) separate body and frame

construction. (Extracted from Automotive Chassis Systems,

p. 2)

2.4 Torsion bar of a common car. 17

2.5 Results of Ackerman Steering test taken at various angles of 18

the steering.

2.6 Common Ackerman steering of a go-kart. 19

2.7 Kingpin inclination. 20

2.8 Scrub radius. 21

2.9 Torque arm caused by scrub radius. 22

2.10 Caster Angle. 23

2.11 Camber. 24

2.12 Toe-in. 25

3.1 Sample chassis found in Cosama Sdn. Bhd. 27

3.2 Go-kart built by students of Polytechnic Kuching. 28

viii

3.3 Kart Data for Windows 95/NT used in calculating the weight 29

distribution on a go-kart. 3.4 Kart Setup by Kyle Davidson. 30

3.5 Designing software for generating drawing of the new 31

chassis- AUTOCAD R14.

3.6 Worktable. 32

3.7 The worktable specially constructed for building the chassis. 33

3.8 Process of heating up the steel pipe for bending process. 34

3.9 Bending process of the frame. 34

3.10 Figures showing steel pipes which have been welded 35

together to make up the outer frame of the chassis. 3.11 Completed frame. 36

3.12 Weight distribution test (without driver). 43

3.13 Weight distribution test (with driver). 43

3.14 17 Degree Method testing. 44

3.15 17 Degree Method testing. 44

3.16 G. I. pipe testing setup. 46

4.1 Spindle Angle. 53

4.2 Caster angle of the front right wheel. 56

4.3 Results obtained from Kart Data 2000.58

ix

List Of Tables

Pages

4.1 Weight distribution of the go-kart. 57

4.2 Results of 17 Degree Method testing. 59

4.3 Result of G. I. pipe testing. 60

4.4 Modulus of Elasticity 61

List Of Graph

Pages

4.1 Deflection versus Load. 61

X

Abstract

The best way to evaluate a functioning go-kart would be testing its performance

under various conditions and points. Therefore, a new go-kart called MechTech-

Initial was presented in this report.

Mech Tech -Initial was constructed based on the common go-kart size

found in the market but with slight difference in the frame design. MechTech-

Initial's chassis was built using steel pipes, bent and welded together, with

consideration to the position of engine position, braking system, steering system,

seat position and many more.

Other go-kart's components such as engine, seat, steering wheel, brake

system, bumper and wheels are mounted to the chassis to test the performance.

The chassis dimensions were taken for further testing and future

reference. Among the tests applied are weight distribution on each wheel, and 17

degree method.

xi

Abstrak

Cara yang paling berkesan untuk menguji persembahan sebuah 'go-kart' adalah

dibawah pelbagai keadaan dan kedudukan. Maka, satu 'go-kart' yang diberi

nama MechTech-initial telah dihasilkan untuk laporan ini.

Mech Tech- Initial telah dibina berdasarkan ukuran go-kart yang lazimnya

dijumpai di pasaran dengan sedikit perbezaan dalam rupabentuk rangka. Cesi

Me ch Tech -Initial dibina dengan menggunakan paip-paip besi yang dibengkok

dan dikimpalkan bersama, dengan mengambilkira kedudukan enjin, system

pembrekan, roda steering, kedudukan kerusi dan sebagainya.

Komponen-komponen go-kart yang lain seperti engine, kerusi, roda

steering, brek, bampar dan roda kemudiannya dipasang ke atas cesi untuk

menguji persembahannya.

Dimensi cesi diambil secara teliti untuk tujuan kajian lanjutan dan rujukan

masa depan. Antara kajian yang dijalankan adalah penyebaran berat pada setiap

roda dan metod 17 darjah.

X11

1 Introduction

With the completion of Sepang International Formula One Circuit,

automobile racing has become one of the most popular sports among

Malaysian. Consequently, go-karting begin to gain more attention as there

is no age limit to this sport. Furthermore, go-kart nowadays requires very

low investment, making it affordable by most people to either purchasing

from public retailer or constructing one in a workshop.

1.1 History of Go-Kart

Go-kart technology has been widely developed since the introduction of

wheels. But, it was not fully implemented in racing activity until the past

three hundred years in America. The first go-kart was simply a cart

consisting of wheels and handles jointed together as children pushed from

behind when learning to walk or a four-wheeler platform where children

can sit on it while another push the kart around.

Go-kart was invented in California by Art Ingels and Lou Borelli

using 100cc mower engines and strong steel frames. Then, newly

designed karts were beginning to gain popularity in Britain around the year

1959-, i960. Go-kart has long existed in our world whether used in sport or

recreation. By definition of International Karting Commission - Federation

International Automobile (CIK-FIA), a kart is defined as a land vehicle with

or without a bodywork, with 4 non-aligned wheels in contact with the

I

ground, two of which control the steering while the other two transmit the

power. Its main parts are the chassis (which consists of a body frame work

that is made up of a set of bent steel pipes that are welded together) with

an engine, four wheels and tyres attached on it.

Figure 1.1 One of karting pioneer, Don Boberick riding the first Rathmann Xterminator prototype kart. (Extracted from http: //www. vintagekarts. com)

Figure 1.2 Don driving the "Drone" at the Rose Bowl parking lot 1957. (Extracted from http: //www. vintagekarts. com)

1.2 Go-Kart Today and Future

Go-kart racing is a cheaper and smaller way of automobile racing not

forgetting, a lot safer compared to other motor racing sports such as

2

Formula One. Today, go-kart racing is not only practiced by adult hut the

younger generation. Allowing an early start on this sport, as young as the

age of 5 or 6 years old. would he beneficial as it is the most suitable period

for them to gain experience to be a professional driver in the future.

Practicing on go-karting can properly expose the driver to the actual racing

environment, training them to be professional motor racer in various

competitions such as Formula One, NASCAR, Indy racing, and others.

Nowadays, go-karting is as popular as it has ever been with

continued growth every year, and the manufacturers who have stayed with

go-kart industries are capable to stabilize and obtain a promising market.

However, the technology in go-karting seems to be stabilizing at a stage

even though minor improvement was done on the performance.

One of the challenges in improving go-karting would be building

more standardized track for the growing number of go-kart's driver.

With continuous improvement in go-kart industry whether on go-kart

designs, equipments, services such as available tracks, or driving

techniques, this sport would surely obtain a very high ranking of popularity

in the near future.

2 Literature Review

2.1 Introduction

Usualiy a go-kart driver or owner who wants to improve the handling of the

vehicle will purchase the latest in wheels, tyres and other optional

equipment, but end up finding that those things in fact handles worse. The

first stage in achieving a good handling kart that will provide the greatest

percentage of power efficiency is to go right back to basics.

The chassis is the framework of any vehicle. The suspension,

steering, and drivetrain components (such as engine, transmission, and

final drive components) are mounted to the chassis. The chassis would

have to be strong and rigid platform to support the suspension

components (James D. Halderman, Chase D. Mitchell, Jr., Automotive

Chassis Systems, 2000, p. 1). Furthermore, the constructions of today's

vehicles require the use of many different materials.

Chassis of a go-kart is not much different from a normal car

chassis, in fact, it is much less complicated. The different in size and

weight make go-kart chassis much easier to design and construct.

2.2 Chassis Design

A typical dictionary definition of chassis usually includes terms such as

framework on which the body or working parts of a vehicle, radio or

4

television are built (Oxford Advanced Learner's Dictionary, p. 190). There

are three basic designs used today: frame, unit-body, and space frame

construction.

2.2.1 Frame Construction

The frame construction usually consists of channel-shaped steel beams

welded and/or fastened together. The frame (chassis) of a vehicle will

supports all the `running gear' mounted on it, including the engine,

transmission, rear axle assembly (if rear-wheel drive), and all the

suspension components.

The type of frame construction that is referred to as full frame, is so

complete that most karts can usually be driven without the body.

Terms and label of different kind of frame are as follows:

Ladder Frame

This type of frame is common for the type of perimeter frame where the

transversely (lateral) connected members are straight across. Figure 2.1

show as a ladder frame sample where viewed with the body removed. The

frame resembled a ladder viewed from top.

Figure 2.1 Ladder frame of a common vehicle.

(Extracted from Automotive Chassis Systems, p. 2)

5

Perimeter Frame

This type of frame consists of welded or riveted frame members around

the entire perimeter of the body (Figure 2.2). The frame members will

provide support underneath the sides as well as for the suspension and

suspension components.

:: Figure 2.2 Perimeter frame of a common vehicle.

(Extracted from Automotive Chassis Systems, p. 2)

Stub-Type Frame

Stub-type frame (Figure 2.3) is a partial frame often used on unit-body

vehicle, a type of vehicle construction, first used by the Budd Company of

Troy, Michigan, that does not use a separate frame. The body is built

strong enough to support the engine and the power train, as well as the

suspension and steering system. The outside body panels are part of the

structure (James D. Halderman, Chase D. Mitchell, Jr., Automotive

Chassis Systems. 2000, p. 495)] to support the power train and

suspension components. It is also called cradle.

6

I. i

Figure 2.3 (a) Unitized construction, the small frame members are for

support of the engine and suspension components. Many vehicle would

attached the suspension components directly to the reinforced sections of

the body and do not required the rear frame section; (b) separate body

and frame construction. (Extracted from Automotive Chassis Systems, p. 2)

2.2.2 Unit-Body Construction

Unit-body construction (sometimes referred as unibody) is designed in

such a way that the body is combined with the structure of the frame. The

body itself supports the engine and driveline components, as well as the

7

suspension and steering components. The body is composed of many

individual stamped steel panels welded together.

The strength of this type of construction lines is in the shape of the

assembly. The arrangement of parts to be jointed or formed not only

provides sufficient strength to withstand high stress but also the stability of

the vehicle during any performances. The typical vehicle uses 300

separate and different stamped steel panes that are spot-welded to form a

vehicle's body.

2.2.3 Space Frame Construction

Space frame construction is a type of vehicle construction that uses the

structure of the body to support the engine and drivetrain as well as the

steering and suspension. The outside body panels are non-structural

(James D. Halderman, Chase D. Mitchell, Jr., Automotive Chassis

Systems, 2000, p. 494)] consists of formed sheet steel used to construct a

framework for the entire vehicle. The vehicle using this type of framework

is drivable without the body. It would only uses plastic or steel panels to

cover the steel framework.

2.3 Platform

The platform of any vehicle is its basic size and shape. Various vehicles of

different makes can share with same platform and, therefore, many of the

same drivetrain and suspension and steering components.

8

A platform of a unit-body vehicle includes all major sheet-metal

components that form the load-bearing structure of the vehicle, which

include the front suspension and engine supporting sections. The area

separating the engine compartment from the passenger's seat is variously

called bulkhead. cowl panel, dash panel, or firewall. The height and

location of this bulkhead panel to a large degree determine the shape of

the rest of the vehicle.

Other components of vehicle platform design that affect handling

and ride are the track and wheelbase of the vehicle the track of a vehicle is

the distance between the wheels, as viewed from the front or rear. A wide-

track vehicle is a vehicle with a wide wheel stance; this increases the

stability of the vehicle especially when cornering. The wheelbase of the

vehicle is the distance between the centre of the front wheel and the

centre of the rear wheel, as viewed from the side. Vehicle with a long

wheelbase tends to ride smoother than vehicle with a short wheelbase

(James D. Halderman, Chase D. Mitchell, Jr., Automotive Chassis

Systems. 2000, p. 3).

2.4 Chassis Materials

Most of the automotive components and parts are made of cast iron, such

as brake drums and rotors, spindles, engine blocks, and many other

components including fasteners. There are different types of steel for each

component, which requires different strengths and characteristic from the

9

material. The amount of carbon in steel is the most important point in

determining the strength, hardness, and machining characteristics.

2.4.1 Galvanized Steel

Galvanized steel is steel with zinc coating which could protect the steel

from corrosion (rust). Another type of rust-resistance steel includes

zincrometal, which is a two-coat bake-on system using chromium oxide

and zinc.

2.4.2 High-Strength Steel

High-strength steel (HSS) has been introduced widely since the mid-

1970s, as many car and light truck parts have been built with it. Application

of HSS is commonly in the sill area under the doors where high strength is

required, yet lightweight is needed. Other applications in vehicles are in

the bumper supports and impact beams in doors.

HSS is very hard, but heating causes it to lose much of its strength.

High-strength steel is low-carbon alloy steel which consists of various

amounts of carbon, silicon, phosphorus, nitrogen, and manganese

(Kalpakjian, Manufacturing Engineering and Technology, 1995, p. 166).

Body repair technicians should always follow manufacturers'

recommended procedures to avoid weakening the structure of the body.

1O

2.5.2 Length

Equalizing both sides' dimensions of the chassis length is very important.

It can be done by heating the front axle and twist the top of the king pin

with the greatest lean back to a more upright position to match the other

side.

2.5.3 Steering Position Alignment

The next step would be aligning the steering position. Firstly, the rims of

the front wheels must be machined so that the inner and outer diameters

on both wheels are all exactly the same size. Then, it is possible to use a

straight edge to check the front wheel alignment.

Centralizing the steering should be done so as to have the kart

steering evenly in both directions, and tracking well in a straight line.

The steering shaft in most modern karts is offset to the brake side

of the kart. With the wheels fitted, it is necessary to find the difference from

the centre of the steering shaft at the steering yoke to the inside of each

front wheel level with the steering arm on the kingpin. This amount of

offset should then be built into the tie rods when the steering yoke is at

bottom dead center (idea quoted from http: //akrweb. com/karting). Then,

the toe in and toe out desired can be adjusted by equa; ly lengthening or

shortening both tie rods. However, the straight edge should first being

placed across the machined wheels to check that both are set on the

same amount of camber before setting the toe in. Front wheel alignment

should only be done if the camber is equal and at the desired angle.

12

2.5.4 Kart Straightness

The kart should be check if it is twisted. With the kart positioned on a flat

floor, place the wheels and tyres back on the kart and with the tyres

correctly inflated, then using a set of scales lift each front wheel by

hooking the scale hook around the king pin. Then spin the wheel lifted and

slowly lower the kart until the wheel touches the floor and note the amount

of lift needed at the point of contact. Each side of the kart should require

the same amount of lift. If this is not the case, the chassis is twisted. To

correct the situation, place the rear wheel on the same side, as the kart is

light at the front and with someone standing on the opposite rear wheel

twist the light front side of the kart down. This should be repeated until the

both front wheels carry the same amount of weight. Once the front is even

the back will also be even (idea quoted from http: //arkweb. com/karting).

The rear axle should be check if it is located central to the chassis.

Firstly, try centering off the chassis tubes and then checking the axle

diagonally with the tops of the king pins to check if the chassis runs out of

line in the centre. If fault was found with the diagonal check in the chassis,

it is best simply offset the axle slightly. Once this is done, the ends of the

rear axle can be used accurately for setting the position of the rear hubs.

2.5.5 Other Jobs

With all the previous 4 jobs done, some other minor activities should then

be carried out. First clean and oil every bearing and moving the chassis

where necessary by removing it from the chassis. Make sure each moving

13

part is in good condition or otherwise, replace it if doubtful. Make sure that

all king pin bearings, steering shaft bearings, tie rod ends, wheel bearings

and axle bearings have a good fit and not sloppy. Finally, check the kart

for any cracks and repair where necessary before putting everything back

together.

Once all the steps have been completed, think about setting up for

a particular class to help setting the engine requirement.

2.6 Basic Go-kart's Chassis Theories

'lt is the responsibility of each karter to determine his own requirements. It

is also the karters responsibility to stay within the sprit and intent of the

rules of the organization in which he will be participating. '(Brian Martin,

Go-kart Racing- Chassis Setup, 2000)

Setting up a good go-kart chassis requires not only the knowledge of basic

theories but also from past experiences. Theories will help beginners in

setting their first go-kart but experiences would help further improve it.

Some of the chassis theories will be discuss in the following section.

2.6.1 Frame Construction

The most important aspect in the frame of a go-kart would be its flexibility,

as it is most crucial during cornering in a race. The flexibility of the frame

can be achieved either by using a particular type of material such as

Chrome-moly, or perhaps just by proper design.

14

Some flexibility is good for a go-kart and even makes setting up

easier, but over the time the frame may not rebound back to its original

condition. According to most chassis builder, current frames in the market

are only good for about 18 months before replacement is needed. Racing

on the same track week after week would cause the frame to take a set,

which diminishes its flexibility. One of the easiest ways to alleviate this

condition is by running several laps in a backward direction on the same

track.

2.6.2 Side Bite

Site bite is the ability of the go-kart to stay stuck on the track without

sliding when going around a corner. With the correct amount of side bite,

the go-kart would unload the inside rear tyre when taking a corner which

will reduce the effect of scrubbing the tyres. However, too much side bite

would cause a hop or bicycle around the corner or scrub off so much

speed causing the engine will bog down. On the other hand, too little side

bite will cause the kart to be loose.

The design of the go-kart frame itself has a lot to do with how much

side bite it has. One good indication is by measuring the width of the rear

frame rails. A narrow kart would measure 24" to 25" while a wider kart has

27" to 28", measured at the center of the frame rails

Side bite is also affected by frame stiffness. The frame is essentially

a series of torsions bars welded together. The shorter the bars and the

more triangulation, the stiffer the frame will be. The frames flexibility can

15