RoadNoize - Recent entries in lexikon

Aerodynamics

03.10.2008 16:44

Automotive aerodynamics is the study of the aerodynamics of road vehicles. The main concerns of automotive aerodynamics are reducing drag (though drag by wide wheels is dominating most cars), reducing wind noise, minimising noise emission and preventing undesired lift forces at high speeds. For some classes of racing vehicles, it may also be important to produce desirable downwards aerodynamic forces to improve traction and thus cornering abilities.

An aerodynamic automobile will integrate the wheel arcs and lights in its shape to have a small surface. It will be streamlined, for example it does not have sharp edges crossing the wind stream above the windshield and will feature a sort of tail called a fastback or Kammback or liftback. Note that the Aptera Typ-1, the Loremo, and the Volkswagen_1-litre_car try to reduce the area of their back. It will have a flat and smooth floor to support the Venturi effect and produce desirable downwards aerodynamic forces. The air that rams into the engine bay, is used for cooling, combustion, and for passengers, then reaccelerated by a nozzle and then ejected under the floor. For mid and rear engines air is decelerated and pressurized in a diffuser, looses some pressure as it passes the engine bay, and fills the slipstream. These cars need a seal between the low pressure region around the wheels and the high pressure around the gearbox. They all have a closed engine bay floor. The suspension is either streamlined (Aptera) or retracted. Door handles, the antenna, and roof rails can have a streamlined shape. The side mirror can only have a round fairing as a nose. Air flow through the wheel-bays is said to increase drag (German source) though race cars need it for brake cooling and a lot of cars emit the air from the radiator into the wheel bay.

Automotive aerodynamics differs from aircraft aerodynamics in several ways. First, the characteristic shape of a road vehicle is bluff , compared to an aircraft. Second, the vehicle operates very close to the ground, rather than in free air. Third, the operating speeds are lower. Fourth, the ground vehicle has fewer degrees of freedom than the aircraft, and its motion is less affected by aerodynamic forces.

Automotive aerodynamics is studied using both computer modelling and wind tunnel testing. For the most accurate results from a wind tunnel test, the tunnel is sometimes equipped with a rolling road. This is a movable floor for the working section, which moves at the same speed as the air flow. This prevents a boundary layer forming on the floor of the working section and affecting the results.

Drag coefficient (Cd) is a commonly published rating of a car's aerodynamic smoothness, related to the shape of the car. Multiplying Cd by the car's frontal area gives an index of total drag. The result is called drag area, and is listed below for several cars. The width and height of curvy cars lead to gross overestimation of frontal area. These numbers use the manufacturer's frontal area specifications from the Mayfield Company Homepage

Anti-lock braking system

03.10.2008 16:44

An anti-lock braking system, or ABS (from the German, Antiblockiersystem) is a safety system on motor vehicles which prevents the wheels from locking while braking.

A rotating road wheel allows the driver to maintain steering control under heavy braking, by preventing a locked wheel or skid, and allowing the wheel to continue to forward roll and create lateral control, as directed by driver steering inputs. Disadvantages of the system include increased braking distances under some limited circumstances (ice, snow, gravel, "soft" surfaces), and the creation of a "false sense of security" among drivers who do not understand the operation, and limitations of ABS.

Since it came into widespread use in production cars (with "version 2" in 1978), ABS has made considerable progress. Recent versions not only handle the ABS function itself (i.e. preventing wheel locking under braking), but also electronic control of the front-to-rear bias known as electronic brakeforce distribution (EBD), traction control system (TCS or ASR), an "emergency" brake assist (BA, EBA or HBA), and electronic stability control (ESP, ESC or DSC), amongst others.

Steering Wheel

03.10.2008 16:47

A steering wheel (also called a driving wheel or hand wheel[citation needed]) is a type of steering control in vehicles and vessels (ships and boats). This article deals with steering wheels in cars; see steering wheel (ship) for the use in vessels.

Steering wheels are used in most modern land vehicles, including all mass-production automobiles as well as light and heavy trucks. The steering wheel is the part of the steering system that is manipulated by the driver; the rest of the steering system responds to such driver inputs. This can be through direct mechanical contact as in recirculating ball or rack and pinion steering gears, without or with the assistance of hydraulic power steering HPS, or as in some modern production cars with the assistance of computer controlled motors EPS. With the introduction of federal vehicle regulation in the United States in 1968, FMVSS 114 required the impairment of steering wheel movement, to hinder motor vehicle theft; in most vehicles this is accomplished when the ignition key is removed from the ignition lock.

Remote car audio controls are often included on the steering wheels of newer vehicles.

Vincent

04.10.2008 15:08

Vincent Motorcycles was a British manufacturer of motorcycles in the United Kingdom from 1928 to 1955. Their Black Shadow is one of the best known high performance motorcycles of the 1950s. In 1955 the company discontinued motorcycle production due to heavy financial losses.

Vincent Motorcycles, "the makers of the world's fastest motorcycles", began with the purchase of HRD Motorcycles, less the factory premises, by Phil Vincent in 1928.

HRD was founded by the British (RFC) pilot, Howard Raymond Davies, who was shot down and captured by the Germans in 1917. Legend has it that it was while a prisoner of war that he conceived the idea of building his own motorcycle, and contemplated how he might achieve that. It was not until 1924 that Davies entered into partnership with E J Massey, trading as HRD Motors. Various models were produced, generally powered by JAP (J A Prestwich) engines.

Unfortunately, even though HRD motorcycles won races the company ran at a loss, and in January 1928 it went into voluntary liquidation. The company was initially bought by Ernest Humphries of OK-Supreme Motors for the factory space, and the HRD name, jigs, tools, patterns, and remaining components were subsequently offered for sale again.

Airbag

03.10.2008 16:22

An airbag is part of a vehicle's safety restraint system, a flexible envelope designed for rapid inflation in an automobile collision, to prevent vehicle occupants from striking hard interior objects such as steering wheels. It is considered a "passive" safety component not requiring any input or action from the user, rather than an "active" component — such as a seat belt, which requires fastening.

Various manufacturers have over time used different terms for airbags. General Motors' first bags, in the 1970s, were marketed as the Air Cushion Restraint System. Common terms in North America include Supplemental Restraint System (SRS) and Supplemental Inflatable Restraint (SIR); these terms reflect the airbag system's nominal role as a supplement to active restraints (i.e., seat belts).

The efficacy of airbags in saving lives and preventing injuries is a controversial subject. One study, cited below, puts the number at just under 400 per year (6,000 total), and another study indicates that airbags reduce fatalities by 8% when seat belts are worn.

Automatic transmission

03.10.2008 16:19

An automatic transmission (commonly "AT" or "Auto") is an automobile gearbox that can change gear ratios automatically as the vehicle moves, freeing the driver from having to shift gears manually. Similar but larger devices are also used for heavy-duty commercial and industrial vehicles and equipment.

Most automatic transmissions have a set selection of possible gear ranges, often with a parking pawl feature that will lock the output shaft of the transmission. Continuously variable transmissions (CVTs) can change the ratios over a range rather than between set gear ratios. CVTs have been used for decades in two-wheeled scooters but have seen limited use in a few automobile models. Recently, however, CVT technology has gained greater acceptance among manufacturers and customers.

Some machines with limited speed ranges or fixed engine speeds, such as some forklift trucks and lawn mowers, only use a torque converter to provide a variable gearing of the engine to the wheels.

Sequential manual transmission

03.10.2008 16:18

A sequential manual transmission (or sequential manual gearbox) is a type of manual transmission used on motorcycles and high-performance cars or auto racing, where gears are selected in order, and direct access to specific gears is not possible.

With traditional manual transmissions, the driver can move from any gear, to any gear, by moving the shifter to the appropriate position. This type of transmission is often referred to as a H-pattern because of the path that the shift lever takes as it selects the various gears. A clutch must be disengaged before the new gear is selected, to disengage the running engine from the transmission, thus stopping all torque transfer. In auto racing, this process is slow and prone to human error; hence the development of the sequential transmission. A true sequential transmission will very often use dog clutch engagement rather than the more usual syncromesh as fitted to a normal H-pattern road car gearbox. Engagement using dogs only requires a very brief interruption of engine torque to complete a shift into any adjacent gear. This allows shifting between gears without the use of the clutch. The clutch would normally be used only for standing starts.

Manual transmission

03.10.2008 16:18

A manual transmission (also known as a stick shift or just 'stick', 'straight drive', or standard transmission) is a type of transmission used in automotive applications. Manual transmissions often feature a driver-operated clutch and a movable gear selector. Most automobile manual transmissions allow the driver to select any forward gear at any time, but some, such as those commonly mounted on motorcycles and some types of racing cars, only allow the driver to select the next-higher or next-lower gear ratio. This second type of transmission is sometimes called a sequential manual transmission.

Manual transmissions are characterized by gear ratios that are selectable by locking selected gear pairs to the output shaft inside the transmission. Conversely, most automatic transmissions feature epicyclic (planetary) gearing controlled by brake bands and/or clutch packs to select gear ratio. Automatic transmissions that allow the driver to manually select the current gear are called semi-automatic transmissions.

Contemporary automotive manual transmissions are generally available with four to six forward gears and one reverse gear, although manual transmissions have been built with as few as two and as many as eight gears. Tractor units have at least 10 gears and as many as 24. Some manuals are referred to by the number of forward gears they offer (e.g., 5-speed) as a way of distinguishing between automatic or other available manual transmissions. Similarly, a 5-speed automatic transmission is referred to as a 5-speed automatic.

Other types of transmission in mainstream automotive use are the automatic transmission, semi-automatic transmission, and the continuously variable transmission.

Ground Effect

03.10.2008 16:33

Ground effect is term applied to a series of aerodynamic effects used in car design, which has been exploited to create downforce, particularly in racing cars. This has been the successor to the earlier dominant aerodynamic theory of streamlining. Champ Cars employed ground effect to some extent, but Formula One and most other racing series' worldwide currently use design constraints to heavily limit its effectiveness.

Differential

03.10.2008 16:33

Differentials are a variety of gearbox, almost always used in one of two ways. In one of these, it receives one input and provides two outputs; this is found in every automobile. In the other, less commonly encountered, it combines two inputs to create an output that is the sum (or difference) of the inputs.

In an automobile and other wheeled vehicles, the differential allows each of the driving wheels to rotate at different speeds, while supplying equal torque to each of them. In automotive applications, the differential and its housing are sometimes collectively called a "pumpkin" (because the housing resembles a pumpkin).

Limited slip differential

03.10.2008 16:33

A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.

Power steering

03.10.2008 16:55

Power steering is a system for reducing the steering effort on vehicles by using an external power source to assist in turning the roadwheels.

It is said that power steering was invented in the 1920s by the late Klara Gailis and George Jessup in Waltham, Massachusetts, USA. However, the earliest known patent related to power steering was filed (as recorded by the US Patent Office) on Aug. 30, 1932, by Francis W. Davis.[1] There is another inventor credited with the invention of power steering by the name of Charles F. Hammond (an American, born in Detroit), who filed similar patents, the first of which was filed (as recorded by the Canadian Intellectual Property Office) on Feb. 16, 1954.[2]

Chrysler Corporation introduced the first commercially available power steering system on the 1951 Chrysler Imperial under the name Hydraguide. Most new vehicles now have power steering, owing to the trends toward front wheel drive, greater vehicle mass and wider tires, which all increase the required steering effort. Modern vehicles would be extremely difficult to maneuver at low speeds (e.g., when parking) without assistance.

V8 Supercars

03.10.2008 16:54

V8 Supercars is a touring car racing category operated under the regulations of the Fédération Internationale de l'Automobile (FIA)[1]. It is the most popular motorsport in Australia, has a considerable following in New Zealand, and is steadily growing in popularity across the world where television coverage allows.

V8 Supercar events are held in all states of Australia as well as rounds in New Zealand and Bahrain. V8 Supercars have drawn crowds of over 250,000 spectators.[2] The 2007 season was held over 14 race weekends on various purpose-built racetracks and street circuits in the aforementioned countries. Race formats range from sprint races, where either two 250km or three 120 km races are held over a weekend, or endurance races such as Bathurst which is run over a 1000 km race distance, and Phillip Island which is run over 500 km.

The V8 Supercars themselves are loosely based on either the Ford Falcon or Holden Commodore. Although they bear some resemblance to the production models outwardly, they are highly modified to suit the motorsport application. They are strictly governed in all aspects of performance in an effort to keep all the drivers on an even footing to create closer, more exciting racing. Because of this, entire fields of 29 drivers are separated by just one second over qualifying laps at some events.

Historically, the Falcon and Commodore are the two most popular passenger cars on the Australian market. Rivalry between the two makes is a major aspect of the sport's appeal.

Chevrolet Straight-6 engine

03.10.2008 17:07

The Chevrolet inline 6 of the 1930s through 1970s was the base engine in many popular cars, including the Chevrolet Camaro.

Chevrolet Small-Block engine

03.10.2008 17:07

Chevrolet's small-block V8 is a famous automobile engine. Nicknamed "mouse motor"[1] (opposed to the big block engines, nicknamed "rat") for its compact dimensions compared to other V8 engines of the time, production began in 1955 with the 265 engine. By 1957 it had grown to 283 in3 (4.6 L), and with the optional Rochester mechanical fuel injection, it became one of the first production engines ever to make one horsepower per cubic inch. This engine was used to power the Corvette, and the Bel Air at that time. It would later be extended to other vehicles as well, and replace the old style 265 V8s. The displacement changed over the years, eventually reaching 400 in3 (6.6 L), but none caught on like the 350 in3 (5.7 L) small-block. This engine is still in production today at General Motors Toluca, Mexico plant (primarily for the GM over-the-counter Goodwrench powerplants), but is no longer offered in current model year vehicles since the year 2004. Its production numbers were impressive, with more than 90,000,000 built. It has been produced in carbureted, mechanical fuel injection, and electronic fuel injection forms.

From 1955-74, the small-block engine was known as the "Turbo-Fire V8".

Although Buick, Cadillac, Oldsmobile, and Pontiac also designed V8 engines (see list of GM engines), it was Chevrolet's 350 in3 (5.7 L) small-block that became the GM corporate standard. Over the years, every American General Motors division except Saturn used the Chevrolet small-block, and its descendants (see GM LT engine and GM LS engine) continue as the company's mainstream V8 design today.

The small-block was on the Ward's 10 Best Engines of the 20th Century list.

Chevrolet tested the small-block twice with no water and no oil at wide-open throttle. The first time it lasted an hour and 15 minutes and the second time it lasted two hours.

Supercharger

03.10.2008 17:06

A supercharger is an air compressor used for forced induction of an internal combustion engine. The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally-aspirated engine, which allows more fuel to be provided and more work to be done per cycle, increasing the power output of the engine.

A supercharger can be powered mechanically by a belt, gear, shaft, or chain connected to the engine's crankshaft. It can also be powered by an exhaust gas turbine. A turbine-driven supercharger is known as a turbosupercharger or turbocharger.

Turbocharger

03.10.2008 17:06

A turbocharger, or turbo, is an air compressor used for forced-induction of an internal combustion engine. Like a supercharger, the purpose of a turbocharger is to increase the mass of air entering the engine to create more power. However, a turbocharger differs in that the compressor is powered by a turbine driven by the engine's own exhaust gases.

Ford Falcon GTHO Phase III

03.10.2008 17:11

The GTHO Phase III was a modified Ford Falcon muscle car produced by Ford Australia in 1971.

Powered by a heavily modified 351 Cleveland motor, with 4 speed top-loader, and Detroit locker 9" differential, the GT-HO was a powerful vehicle. It was also equipped with special brakes and handling package, plus a 36 gallon fuel tank. The Phase 3, as it is referred to by some purists, was very successful in the Australian Touring Car Championship (1973 ATCC winner Allan Moffat drove a Phase 3). It was described by Sports Car World as "...simply one of the best cars in the world, a true GT that could take on Ferraris and Astons on their own terms." EBay Buyer's Guide XY Falcon GTHO Auction

Ford Windsor engine

03.10.2008 17:39

The Windsor engine is a 90-degree small-block V8 from Ford Motor Company. It was introduced in 1962, replacing the old Ford Y-block engine. Though not all of the engines in this family were produced at the Windsor, Ontario engine plant (all Ford small blocks came from Cleveland, Ohio until 1966), the name stuck. The mid-sized 335 "Cleveland" V8, introduced in 1970, was to replace the larger Windsors, but this design ended up outliving its replacement. In 1991, the Windsor engine began to be phased out and replaced with Ford's new 4.6 L modular V8 engine, which was disliked by many because of the overhead cam valvetrain as opposed to the more traditional "muscle car-ish" pushrod V8 with overhead valves that Chevy stuck with in their GM LS engine line. In 1996, Ford replaced the popular 5.0 L pushrod V8 with the 4.6 L in their flagship vehicle, the Ford Mustang. Its use in production vehicles continued until 1997 in the F-150 and until 2001 in the Ford Explorer. As of 2008 the Windsor engines including the 351 and 302 are still being produced by Ford, available as complete crate motors, from Ford Racing and Performance Parts.

Ford 335 engine - Cleveland V8

03.10.2008 17:39

The Ford 335 engine family were a group of small-block V8 engines built by the Ford Motor Company between 1970 and 1982. The significance of the Numerals '335' designated to this series of Small block Ford V8 engines is relatively unknown. Conjecture relating to this designation revolves around a prototype 335 CID (Cubic Inch Displacement) engine Ford developed for the Marine industry; to design a V8 motor eliminating the need for water to pass through the inlet manifold and to delete the need for a separate cam timing cover. The series was nicknamed Cleveland after the Cleveland, Ohio engine plant in which most were manufactured. The 335 was used as an option in mid-sized vehicles and trucks concurrently with the larger 351 member of the Windsor small-block family as well as the mid-sized FE V8 family. Although all three of these engine families continued in production the Cleveland, only outliving the FE by a half-decade, was eventually abandoned in favor of the more compact Windsor design.

Chrysler Hemi engine

03.10.2008 17:40

A Chrysler Hemi engine, known by the trademark Hemi, is an internal combustion engine built by Chrysler that utilizes a hemispherical combustion chamber. Chrysler built three generations of hemi engines for automobiles: the first (known as the Chrysler FirePower engine) in the 1950s, the second from the mid-1960s through the mid-1970s, and the third in the early 2000s.

A hemispherical (i.e., bowl-shaped) combustion chamber allows the valves of a two valve-per-cylinder engine to be angled rather than side-by-side. This creates more space in the combustion chamber roof for the use of larger valves and also straightens the airflow passages through the cylinder head. These improvements significantly improve the engine's airflow ("breathing") capacity, which can result in relatively high power output from a given piston displacement. With a hemi combustion chamber, there is minimal quench and swirl to burn the fuel-air mix thoroughly and quickly; the spark plug is frequently located at or near the centroid of the chamber to facilitate complete combustion. Engines with hemispherical combustion chambers often use dome-topped pistons to attain the desired compression ratio.

The advantages of the hemi cylinder head come at the disadvantage of requiring intake and exhaust valve stems that point in different directions, requiring a much more complex rocker arm geometry in both cam-in-block and overhead cam engines. This also increases the space taken up by the cylinder head. Also, the hemi design lacks the quench area that exists with wedge combustion chamber designs, making the hemi more sensitive to fuel octane—a given compression ratio will require higher octane to avoid ping in a hemi engine than in an engine with wedge combustion chambers.

Wankel Engine

04.10.2008 15:08

The Wankel engine is a type of internal combustion engine which uses a rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. Its four-stroke cycle is generally generated in a space between the inside of an oval-like epitrochoid-shaped housing and a roughly triangular rotor. This design delivers smooth high-rpm power from a compact, lightweight engine.

The engine was invented by engineer Felix Wankel. He began its development in the early 1950s at NSU Motorenwerke AG (NSU) before completing a working, running prototype in 1957. NSU then subsequently licenced the concept to other companies across the globe, who added more efforts and improvements in the 1950s and 1960s.

Because of their compact, lightweight design, Wankel rotary engines have been installed in a variety of vehicles and devices such as automobiles and racing cars, aircraft, go-karts, personal water craft, and auxiliary power units.

Ford Model B (1932)

04.10.2008 15:27

The Model B was a new Ford automobile produced in model year 1932. It was a much updated version of the Model A and was replaced by the 1935 Ford Model 48. Strictly speaking the Model B was a four-cylinder car with a Ford Model A engine, but it was at this time that Ford began producing a very similar car with Ford's new Flathead V8 engine. The V8 car was marketed as a Model 18, though it is commonly called the Ford V-8 today, and was virtually indistinguishable from the Model B. Until this time, Ford had always produced only one basic car at a time.

There were two versions of the ’32 – a four-cylinder and the V8 flathead. They came in two body styles, the "5-window" (two door windows, two quarter panel windows and the rear window), and the rare "3-window" Deluxe Coupe that featured front opening doors, also known as Suicide Doors. The Deuce was called Model 18, the “1” standing for “first” and the “8” for V-8. The less popular Model B was the four-cylinder model, a refined version of the four-cylinder Model A.

The ’32 Model 18 was the first successful V-8 in a low-priced car. The 65-hp engine was used in some models costing $460. There were 14 different body styles – like the roadster, coupe, sport coupe, two-door and four-door sedans, cabriolet and phaeton. Prices ranged from $460 for the roadster and the coupe's $490 to the $650 convertible sedan. Production totals numbered only 520 for the roadster and 28,904 for the two-door coupe. Nowadays, the roadster and coupe are notable, as these body styles are more used in making the models into streetrods.

Today, the 1930s Model B is a highly collectible car that people will pay thousands of dollars to restore to exact original style. During the WWII period, when they were first getting old, the Model Bs and V8s were frequently altered into hot rods. This continued into the 1960s on a large scale. Since the 1970s, 1932 bodies and frames have been expensive, which has reduced the number of "rods" being created. Those that are made, however, are quite evolved and often very expensive. A typical auto-show hot rod is a $60,000 proposition or much more, in a few cases.

Ford Model A (1927)

04.10.2008 15:27

The Ford Model A (1927 - 1931) was the second huge success for the Ford Motor Company, after its predecessor, the Model T. First produced on October 20, 1927, but not sold until December 2, it replaced the venerable Model T, which had been produced for 18 years. This new Model A (a previous model had used the Model A name back in 1903) was designated as a 1927 model and was available in four standard colors, but not black.

The successor to the Model A was the Model B which featured an updated 4-cylinder engine, followed by the Model 18 which introduced Ford's new V8 engine.

Chevrolet Camaro

04.10.2008 15:26

The Chevrolet Camaro is a "pony car" made in North America by the Chevrolet Motor Division of General Motors. It was introduced on 26 September 1966 as a 1967 model year and was designed as a competing model to the Ford Mustang. The car shared the platform and major components with the Pontiac Firebird, also introduced in 1967. Four distinct generations of the car were produced before production ended in 2002. A new fifth-generation Camaro will roll off assembly lines in spring of 2009.

Leyland P76

04.10.2008 15:43

The Leyland P76 was a large car produced by Leyland Australia, the Australian subsidiary of British Leyland. It was intended to provide the company with a genuine rival to large local models like the Ford Falcon, the Holden Kingswood, and the Chrysler Valiant.

Prior to P76, Leyland Australia and its antecedent BMC (Australia) had not fielded a direct competitor in this market sector, which dominated the Australian car market. P76 was intended to provide that competitor.

Previously, BMC and Leyland had tried to compete in this market segment with a variety of cars: the 1958 Morris Marshall (a rebadged Austin A95); the 1962 Austin Freeway and Wolseley 24/80 (the Freeway was an Austin A60 with Riley 4/72 tail lights, a unique full width grille and a 2.4 litre 6-cylinder version of the 1622 cc B-series engine; the Wolseley was a 6-cylinder version of the Wolseley 16/60); and the 1971 Austin "X6" Tasman and Kimberley (facelifted Austin 1800s with the 6-cylinder 2.2 litre E-series engine.)

Each of these cars was a compromise, and the motoring public ignored these cars as challengers to the dominant local models. Nonetheless, the Freeway, 24/80 and the X6s each developed a loyal following.

Launched in 1973, it was nicknamed "the wedge", on account of its shape, with a large boot (trunk), able to easily hold a 44 gallon drum. Although station wagon and "Force 7" coupé versions were designed, these never went into mass production.

Harley-Davidson

04.10.2008 15:42

In 1901, William S. Harley, age 21, drew up plans for a small engine with a displacement of 7.07 cubic inches (116 cc) and four-inch (102 mm) flywheels. The engine was designed for use in a regular pedal-bicycle frame.

Over the next two years Harley and his boyhood friend Arthur Davidson labored on their motor-bicycle using the northside machine shop at the home of their friend, Henry Melk. It was finished in 1903 with the help of Arthur's brother, Walter Davidson. Upon completion the boys found their power-cycle unable to conquer Milwaukee's modest hills without pedal assistance. Will Harley and the Davidsons quickly wrote off their first motor-bicycle as a valuable learning experiment.[11]

Work immediately began on a new and improved second-generation machine. This first "real" Harley-Davidson motorcycle had a bigger engine of 24.74 cubic inches (405 cc) with 9-3/4 inch flywheels weighing 28 pounds. The machine's advanced loop-frame pattern was similar to the 1903 Milwaukee Merkel motorcycle (designed by Joseph Merkel, later of Flying Merkel fame.) The bigger engine and loop-frame design took it out of the motorized-bicycle category and would help define what a modern motorcycle should contain in the years to come. The boys also received help with their bigger engine from outboard motor pioneer Ole Evinrude, who was then building gas engines of his own design for automotive use on Milwaukee's Lake Street.

The prototype of the new loop-frame Harley-Davidson was assembled in a 10- by 15-foot (3 by 5 meter) shed in the Davidson family backyard. Most of the major parts, however, were made elsewhere, including some probably fabricated at the West Milwaukee railshops where oldest brother William A. Davidson was then toolroom foreman. This prototype machine was functional by 8 September 1904 when it competed in a Milwaukee motorcycle race held at State Fair Park. It was ridden by Edward Hildebrand and placed fourth. This is the first documented appearance of a Harley-Davidson motorcycle in the historical record.[12]

In January 1905, small advertisements were placed in the "Automobile and Cycle Trade Journal" that offered bare Harley-Davidson engines to the do-it-yourself trade. By April, complete motorcycles were in production on a very limited basis. That year the first Harley-Davidson dealer, Carl H. Lang of Chicago, sold three bikes from the dozen or so built in the Davidson backyard shed. (Some years later the original shed was taken to the Juneau Avenue factory where it would stand for many decades as a tribute to the Motor Company's humble origins. Unfortunately, the first shed was accidentally destroyed by contractors in the early 1970s during a clean-up of the factory yard.)

In 1906, Harley and the Davidsons built their first factory on Chestnut Street (later Juneau Avenue). This location remains the Motor Company's corporate headquarters today. The first Juneau Avenue plant was a 40 by 60-foot (18 m) single-story wooden structure. That year around 50 motorcycles were produced.