Continuously Variable Transmissions

Continuously Variable Transmissions, or CVT's, as they are called in the trade, are used in snowmobiles, some all terrain vehicles (ATV's), and a few automobiles. A continuously variable transmission works just like it sounds. It continuously varies the gear ratios between the engine and the final drive. There is no need to select different gears: just place the shifter in forward and away you go.

Why use a CVT rather than a conventional automatic or manual transmission? The answer is efficiency; engine efficiency. With a CVT, the engine goes from an idle to a pre-programmed rpm immediately so the engine input is constant, and the transmission varies the output speed for smooth, seamless acceleration. Keeping the engine at a constant rpm allows the engineers to optimise ignition timing, camshaft design, and manifold tuning for excellent volumetric efficiency and low emissions.

Other reasons for using CVT's include simplicity of design, and smooth power application to the ground. The simplicity part comes by using fewer parts. Vehicles with reverse gear obviously have more parts than a simple forward drive, but there are still fewer parts and gears to manufacture.

The smooth power application of CVT's is useful in off-road vehicles. Power can be applied without any jerks or surges that could cause the vehicle to lose traction on steep climbs or loose terrain.

So how do they work? The two most common systems use a belt or a chain. Let's look at snowmobiles first. They use a belt. On a snowmobile there are two pulleys connected by a rubber drive belt. Both pulleys are "V" shaped and the width of the "V" can be varied. The drive pulley is connected to the engine and the width of the pulley is controlled by engine speed. At idle, the pulley is wide and the belt is not gripped. Push on the throttle, and the governor causes the pulley sides to move together. When engine speed reaches it's maximum, the pulley continues to become narrower as vehicle speed increases, causing the drive belt to climb up and keeping the engine at its peak power.

The driven pulley also varies its width, but its main job is to keep the slack out of the belt. The driven pulley halves are spring loaded to force them together, and as the drive pulley closes up, the belt climbs up the drive pulley causing the belt to tighten, forcing the driven pulley apart. The variable width of the pulleys and the variable distance of the belt from the centre of the pulleys provide the continuously variable drive.

Automobiles with CVT's use a drive chain instead of a rubber belt. The chain is stronger and more durable on a much heavier vehicle. Although much more complex, automotive CVT's use variable width pulleys just like snowmobiles. Hydraulics and computer controls are used to vary the width of the drive pulley.

Carbon fiber, new aluminum structure lighten 2014 Corvette Stingray


The all-new 2014 C7 Corvette is a lightweight materials-fest. The base model gains a carbon-fiber hood (inner and outer) and roof panel. Quarters, doors, and hatch are in lighter-density SMC than the previous fenders, and the fascias are in TPO.

“We had very aggressive weight-reduction targets on this program,” said Leonard Brohl, Lead Engineer for Closure Panels on the 2014 C7 Chevrolet Corvette, unveiled Jan. 13 at a media event preceding the Detroit Auto Show. General Motors has resurrected the Stingray name for the latest generation of its iconic sports car, which continues to be a lightweight-materials wellspring for the automaker.

The C7, which enters production in 3Q13, boasts an all-new aluminum chassis/passenger cell structure that is 57% stiffer in torsion and 99 lb (45 kg) lighter than the previous C6 steel-and-aluminum structure, said GM engineers. At the car’s world debut, GM had not yet published a production curb weight for the car. It is expected to be slightly lighter overall than the base C6 coupe's 3208 lb (1455 kg).

Besides reducing mass while increasing strength, the development team aimed to retain the Corvette’s ideal 50/50 front/rear weight distribution deemed essential for superior handling.

Compared to the C6, which uses continuous hydroformed main frame rails with a constant 2-mm (0.08-in) wall thickness, the C7’s main rails each feature five aluminum segments, including extrusions at each end, a center main rail section, and hollow-cast nodes at the suspension interface points. Each segment is tuned by varying wall thickness from 2 to 11 mm (0.08 to 0.433 in). This tailors each section’s gauge, shape, and strength properties to optimize the structural requirements for each frame section while keeping mass to a minimum.

The frame is assembled at an all-new welding shop at the Bowling Green, KY, assembly plant using a precision laser welding process that GM claims holds tolerances to about 0.001 in (0.025 mm).

Supporting the frame’s greater strength and lower weight are complementing chassis elements, including hollow-cast aluminum front and rear cradles that are approximately 25% lighter and 20% stiffer than the solid cradles used on the C6 car’s structure. The steering column support is stiffened by a factor of five compared with the outgoing car using a new thin-wall magnesium casting.

C7’s use of materials includes a standard carbon-fiber hood and roof panel, supplied by Plasan Carbon Composites’ new Walker, MI, plant. Plasan has innovative manufacturing processes that shatter previous autoclave-type processing times, getting per-part processing down to 17-min machine cycles.

The unique balsa-wood-sandwich floor construction of the C6 Corvette has been superseded on C7 by a new carbon nano-composite floor pan that is lighter while maintaining strength and stiffness, said Chief Engineer Tadge Juechter.

C7’s front fenders, doors, rear quarter panels, and the rear hatch panel are made with lighter-density sheet molding compound (SMC) than the previous generation. The door outer panel measures 1.2 mm (0.047 in) thick and the inner panel 0.8 mm (0.031 in). Combined, the body materials and their design/engineering save approximately 37 lb (17 kg) vs. the C6 body structure.

C7 seat frames are a new magnesium structure on both the standard GT seat and the Competition Sport seat with more aggressive side bolstering.

Juechter said that the Stingray's 50/50 weight balance combined with its estimated 450 hp (335 kW) output (final SAE ratings are not yet finalized) offers the new Corvette a power-to-weight ratio that is superior to those of the Porsche 911 Carrera and Audi R8.

A Torsen limited-slip differential

A Torsen ("TORque SENsing") limited-slip differential isn't technically a limited slip differential. It's to call it just a Torsen differential or a helical differential.

The Torsen differential* is a purely mechanical device; it has no electronics, clutches or viscous fluids.

­The Torsen (from Torque Sensing) works as an open differential when the amount of torque going to each wheel is equal. As soon as one wheel starts to lose traction, the difference in torque causes the gears in the Torsen differential to bind together. The design of the gears in the differential determines the torque bias ratio. For instance, if a particular Torsen differential is designed with a 5:1 bias ratio, it is capable of applying up to five times more torque to the wheel that has good traction.

These devices are often used in high-performance all-wheel-drive vehicles. Like the viscous coupling, they are often used to transfer power between the front and rear wheels. In this application, the Torsen is superior to the viscous coupling because it transfers torque to the stable wheels before the actual slipping occurs.

However, if one set of wheels loses traction completely, the Torsen differential will be unable to supply any torque to the other set of wheels. The bias ratio determines how much torque can be transferred, and five times zero is zero.



Hummer!

The HMMWV, or Hummer, uses Torsen® differentials on the front and rear axles. The owner's manual for the Hummer proposes a novel solution to the problem of one wheel coming off the ground: Apply the brakes. By applying the brakes, torque is applied to the wheel that is in the air, and then five times that torque can go to the wheel with good traction.

Inside Bruce Crower’s Six-Stroke Engine

Inside Bruce Crower’s Six-Stroke Engine

Bruce Crower has lived, breathed and built hot engines his whole life. Now he’s working on a cool one—one that harnesses normally-wasted heat energy by creating steam inside the combustion chamber, and using it to boost the engine’s power output and also to control its temperature.

“I’ve been trying to think how to capture radiator losses for over 30 years,” explains the veteran camshaft grinder and race engine builder. “One morning about 18 months ago I woke up, like from a dream, and I knew immediately that I had the answer.”

Hurrying to his comprehensively-equipped home workshop in the rural hills outside San Diego, he began drawing and machining parts, and installing them in a highly modified, single-cylinder industrial powerplant, a 12-hp diesel he converted to use gasoline. He bolted that to a test frame, poured equal amounts of fuel and water into twin tanks, and pulled the starter-rope.

“My first reaction was, ‘Gulp! It runs!’” the 75-year-old inventor remembers. “And then this ‘snow’ started falling on me. I thought, ‘What hath God wrought…’”

The “snow” was flakes of white paint blasted from the ceiling by the powerful pulses of exhaust gas and steam emitted from the open exhaust stack, which pointed straight up.

Over the following year Crower undertook a methodical development program, in particular trying out numerous variations in camshaft profiles and timing as he narrowed the operating parameters of his patented six-stroke cycle.

Recently he’s been trying variations of the double-lobe exhaust cams to delay and even eliminate the opening of the exhaust valve after the first power stroke, to “recompress” the combustion gasses and thus increase the force of the steam-stroke.

The engine has yet to operate against a load on a dyno, but his testing to date encourages Crower to expect that once he gets hard numbers, the engine will show normal levels of power on substantially less fuel, and without overheating.

“It’ll run for an hour and you can literally put your hand on it. It’s warm, yeah, but it’s not scorching hot. Any conventional engine running without a water jacket or fins, you couldn’t do that.”

Indeed, the test unit has no external cooling system—no water jacket, no water pump, no radiator; nothing. It does retain fins because it came with them, but Crower indicates the engine would be more efficient if he took the trouble to grind them off. He has discarded the original cooling fan.

So far he has used only gasoline, but Bruce believes a diesel-fueled test engine he is now constructing—with a hand-made billet head incorporating the one-third-speed camshaft—will realize the true potential of his concept.


Potential…and Questions

Crower invites us to imagine a car or truck (he speaks of a Bonneville streamliner, too) free of a radiator and its associated air ducting, fan, plumbing, coolant weight, etc.

“Especially an 18-wheeler, they’ve got that massive radiator that weighs 800, 1000 pounds. Not necessary,” he asserts. “In those big trucks, they look at payload as their bread and butter. If you get 1000 lb. or more off the truck…”

Offsetting that, of course, would be the need to carry large quantities of water, and water is heavier than gasoline or diesel oil. Preliminary estimates suggest a Crower cycle engine will use roughly as many gallons of water as fuel.

And Crower feels the water should be distilled, to prevent deposits inside the system, so a supply infrastructure will have to be created. (He uses rainwater in his testing.) Keeping the water from freezing will be another challenge.

But the inventor sees overriding benefits. “Can you imagine how much fuel goes into radiator losses every day in America? A good spark-ignition engine is about 24 percent efficient; ie., about 24 cents of your gasoline dollar ends up in power. The rest goes out in heat loss through the exhaust or radiator, and in driving the water pump and the fan and other friction losses.

“A good diesel is about 30 percent efficient, a good turbo diesel about 33 percent. But you still have radiators and heavy components, and fan losses are extremely high on a big diesel truck.”

Bottom-line, Bruce estimates his new operating cycle could improve a typical engine’s fuel consumption by 40 percent. He also anticipates that exhaust emissions may be greatly reduced. It’s all thanks to the steam.

“A lot of people don’t know that water expands 1600 times when it goes from liquid into steam. Sixteen hundred! This is why steam power is so good. But it’s dangerous…”

The danger of a boiler explosion has long been a factor in engineering—and in operating—steam powerplants of all kinds, and Crower is properly wary of the miniature boiler he has conjured up inside his test engine. That’s one reason he chose to use one originally manufactured as a diesel, for its inherent strength, though he installed a carburetor and ignition system so it could burn gasoline at first.

The original diesel fuel injector system now supplies the water spray to generate the steam-stroke.

In addition to producing extra power, the injected water cools the piston and exhaust valve, which suggests to Crower that he could raise the compression ratio. “I’ve done this many times on regular engines: 15-to-1 on gasoline for the first five seconds works pretty good until you get some chamber heat and then suddenly it gets into pinging. But with the chamber being chilled, I bet 12-, 13-to-1 will be no problem on cheap fuel.

“So what we can maybe do is have fuels that aren’t quite as good…It’ll save a nickel a gallon not having to keep three grades going.”

As for his hope of lowering emissions, Bruce speculates the steam might purge “cling-on hydrocarbons” out of the combustion chamber. “This thing may turn out to be so clean that you won’t have to have a catalytic converter.

But he admits that’s unknown, saying “there’s a lot of experimenting still to be done.” Which prospect makes him smile. He thrives on this kind of challenge.


Bruce’s Background

“You’ve kinda got to be in the cam business and know the dynamics of engines,” Bruce Crower says about how the idea occurred to him. And he certainly has that background.

He was building and racing hot rods (and hot bikes), manufacturing speed equipment and operating his own speed shop in his home town of Phoenix when he was still a teen.

After moving to San Diego in the 1950s, among other exploits he dropped a Hemi into a Hudson and drove it to a 157-mph speed record at Bonneville.

Inevitably, the inventive and inexhaustible Crower built up a major equipment business in superchargers, intake manifolds, clutches and, especially, camshafts. He’s also credited with first suggesting a rear wing to Don Garlits—in 1963, three years before Jim Hall’s winged Chaparral. Bruce Crower is now in Florida’s Drag Racing Hall of Fame.

Crower actually had introduced a wing two years earlier, during practice on Jim Rathmann's 1961 Indianapolis car—five years before Jim Hall’s winged Chaparral. Bruce had been crewing at the Speedway since 1954 (Jimmy Bryan, second place), and had been part of Rathmann's 1960 victory effort. He was likewise on the winning teams in 1966 (Graham Hill) and 1967 (AJ Foyt). Three decades later, in 1998, Eddie Cheever won with Crower cams.

Bruce even produced his own complete Indy engine, a flat-8 that didn’t quite make the field in 1977 and then was rendered obsolete (due to its width) by the advent of ground-effect tunnels. But the Crower 8 and its automatic clutch did win an SAE award for innovation.

Today, Crower Cams and Equipment Company employs about 160 people in five facilities, and manufactures not only cams but crankshafts and connecting rods—including titanium rods for (unnamed) Formula One customers.

Bruce Crower can’t be called retired now, but he’s happy to let the company he founded “roll along” while he “plays with cars.” That’s how he looks at the intensive R&D work he carries out in the privacy of his 13-acre horse property near the rural community of Jamul.

One of several projects is building up Honda S2000 engines for the Midget raced by his granddaughter, Ashley Swanson. (“I think she’s on par with Danica Patrick,” says the proud grampa.)

But his prime focus is proving his six-stroke engine is as revolutionary as he believes it is. “I’ve been trying to find something wrong with the whole basic idea for almost a year,” he says, “but I think we’re going to have a very marketable item.”

Then he adds philosophically, “If it turns out to be great, fine. If it doesn’t, it’s just another year out of my life that I’ve had a lot of fun doing something.”

Parx Super Car Show 2013 revs up Mumbai's weekend

 The fifth edition of the Parx Super Car Show took place at the Polo Grounds, RWITC (Mahalaxmi Race Course). Retired world champion rally driver Hannu Mikkola was present as the guest of honour. This year's event was divided into two days- day one being the static display and day two was the Super Car parade.

A major highlight of the show was the showcasing of the Lamborghini Aventador Roadster and the facelifted Audi R8. Also, the Y2k hyperbike was on display at the show.

Like its previous editions, the show displayed cars from manufacturers like Audi, Mercedes, Lamborghini, Aston Martin, Porsche, Ferrari, Bentley and Rolls-Royce for car enthusiasts in the city The second day of the event saw the super cars drive past the streets of Mumbai.

All Car Logo

Grail Engine

It's a very high-tech two-stroke engine that uses forced induction, direct injection and other technologies for impressive power and efficiency.

How it differs from conventional two-stroke engine ?

The engine is based on The Grail Cycle," which is a combination of one type of ignition or homogeneous charged compression ignition while simultaneously operating in the Miller Cycle.

Engine produces power every revolution per-cylinder. because of only two strokes.

The engine can operate on literally any combustible, including propane, natural gas and diesel.

 The piston and compression chamber constantly have cool air moving through the center of their masses, heat soak is reduced, which allows fuel injection to occur at any time and in turn reduces NOx emissions.

It's cheap to produce—there are very few parts involved and many can be simple castings so it is light for its power output.

The Grail Engine has the potential to be the first two stroke engine that does not exhibit cross contamination of fuel and oil. This results in lower emissions yet produces more power and torque using less fuel than larger engines.

Applications :

It could be applied to every area of life, from automobiles to aircraft, and recreational and industrial engines.

Advertisement Of An Antique Gasoline Engine

 The well-known Otto engine was invented by Dr. Nicholas Otto, of Germany, and was patented in this country in 1877. It follows the cycle that has been described by Beau de Rochas , now known as the four-cycle, or sometimes as the Otto cycle. The engine was first known as the Otto-Silent, to distinguish it from the free-piston engine, which was rather noisy. It immediately established the internal-combustion engine on a firm footing, and the engines of the four-cycle type sold today show merely minor improvements. The sliding valve on 1876 has been replaced by poppet valves, and the flame ignition has been replaced by the electric spark. Otherwise, the Otto cycle of 1876 has persisted and at this time thousands of them are being manufactured.

Top 4 Emerging Auto Industry Innovations

Cars may not yet be airborne, as predicted by the reliable forecaster Back To The Future. But they’re still capable of wowing the masses with their ever-expanding arsenal of technologies.

January is a key month for the automotive industry, with the world’s largest electronics gathering in Las Vegas as well as the expansive auto show in the car capital Detroit. A main focal point at each of these events is forthcoming cutting edge automotive innovations. Intelligent cars are creating widespread industry buzz, as the world increasingly relies on intuitive machines to accomplish everyday tasks. At the Detroit Auto show, major brands are pushing each other aside to tout their cutting-edge capabilities.

The business of cars is getting bigger every year. Here are the four emerging innovations that will be coming soon to a showroom near you.

Going Green

Cars are becoming more alike as the gap between luxury and affordable rapidly closes. They’re also striving to be fuel efficient in an era where America’s level of oil consumption is being questioned.

For several years, the Toyota Prius has dominated the hybrid market with its landmark vehicle Prius. Now Ford has entered the space with its own sleek hybrid the “C-Max.” Mileage efficient vehicles are becoming a priority across the industry, as America looks to wean itself off its fuel addiction.

Dashboard Infotainment Systems

Connectivity is upon us. With Ford unleashing its new cloud-based SYNC system, the driver’s external existence is seamlessly transferred into the driving experience. You can customize your favorite entertainment tools, retrieve real-time traffic information, and even have your store your personal in-car preferences.

And companies like Hyundai are integrating voice-command activation into their new vehicles. The way cars use navigation is changing before our eyes with services like Inrix Parking, which shows drivers real-time availability and rate information. Major brands like Toyota, Ford and Audi have already realized the value of smart parking.

Driver-less Driving

One of the cooler news stories of 2012 was Google’s unveiling of its “driverless car.” Imagine the possibility of taking a nice long drive up the California coast while simultaneously being able to catch up on work from your laptop.

While Google has been extensively testing its “computer-led driving,” it still seems like something out of a science fiction movie. “The Google Connected Car,” also Lexus has one too: http://www.digitaltrends.com/ces/lexus-steps-up-to-google-with-its-own-self-driving-car-at-ces-2013/

Self-Parking Vehicles

We’re still a ways off from cars that can auto-drive, brush your hair, floss your teeth all while fixing up a cafe latte. Now that would be something. But we’re actually much closer than you think to cars that can intelligently park themselves.

Some people struggle mightily with the parallel parking, and soon that task will be completely obsolete. This innovation has the potential to disrupt the entire valet parking industry. The Audi A7 can park itself, and then be summoned to pick up the driver by smartphone. Amazing.

Increased mileage

Photo Courtesy of The Auto Channe

Read more at http://www.business2community.com/automotive/top-4-emerging-auto-industry-innovations-0379051#lOmB56Q6q85B6M3v.99 

Formula One

Formula One, also known as Formula 1 or F1 and referred to officially as the FIA Formula One World Championship, is the highest class of single-seater auto racing sanctioned by the Fédération Internationale de l'Automobile (FIA). The "formula", designated in the name, refers to a set of rules with which all participants' cars must comply. The F1 season consists of a series of races, known as Grands Prix (from French, originally meaning great prizes), held throughout the world on purpose-built circuits and public roads. The results of each race are evaluated using a points system to determine two annual World Championships, one for the drivers and one for the constructors. The racing drivers, constructor teams, track officials, organisers, and circuits are required to be holders of valid Super Licences, the highest class of racing licence issued by the FIA.

Formula One cars are among the fastest circuit-racing cars in the world, owing to very high cornering speeds achieved through the generation of large amounts of aerodynamic downforce. Formula One cars race at speeds of up to 350 km/h (220 mph) with engines limited in performance to a maximum of 18,000 revolutions per minute (RPM). The cars are capable of lateral acceleration in excess of 5 g in corners. The performance of the cars is very dependent on electronics – although traction control and other driving aids have been banned since 2008 – and on aerodynamics, suspension and tyres. The formula has had much evolution and change through the history of the sport.

While Europe is the sport's traditional base, and hosts about half of each year's races, the sport's scope has expanded significantly during recent years and an increasing number of Grands Prix are held on other continents. Formula One had a total global television audience of 527 million people during the course of the 2010 FIA Formula One World Championship.

Such racing began in 1906 and, in the second half of the 20th century, became the most popular type internationally. The Formula One Group is the legal holder of the commercial rights. With annual spending totalling billions of US dollars, Formula One's economic effect and creation of jobs is significant, and its financial and political battles are widely reported. Its high profile and popularity make it a merchandising environment, which results in great investments from sponsors and budgets in the hundreds of millions for the constructors. Since 2000 the sport's spiraling expenditures have forced several teams, including manufacturers' works teams, into bankruptcy. Others have been bought out by companies wanting to establish a presence within the sport, which strictly limits the number of participant teams.

History of Cars part C

Antique or Brass Era (1905 - 1914)
"The antique or brass era lasted from roughly 1905 through to the beginning of World War I in 1914. This era saw the first mass produced vehicles with gasoline engines, immortalized by Henry Ford's model T. The brass era was named for the widespread use of the fancy brass fittings and brass lanterns that adorned the new 'horseless carriage'.1905 was a signal year in the development of the automobile, marking the point when the majority of sales shifted from the hobbyist and enthusiast to the average user. Brass began to be phased out about 1914 in favor of nickel, which was eventually abandoned in favor of chrome.

Within the 15 years of this era, the various experimental designs and alternate power systems would be marginalized. Steam power proved too cumbersome and electric motors were limited by battery technology (as they still are today), but gasoline was cheap and plentiful, encouraging both two-stroke and four-stroke development."

Far from luxurious these vehicles were mainly owned by the rich. With no doors, windscreen wipers or heaters and with the inconvenience of headlights lit by a match, they must have been an encumbrance to drive around. The engine was started with a crank and in wet and windy weather it was a real horror.

My grandmother bought a car of a later type in which we motored many a happy mile. But by that time they were second hand and almost giveaways as the newer more streamlined limousines came into being. The one she purchased had doors but it started only with a crank and was very high off the ground. It had a running board on either side of the vehicle on which you first stepped to enter it. As a teenager I also had great fun as with some friends we motored around Sydney in a similar vehicle, usually laughing our head off and freezing in the drafts coming through the perspex side windows, or blinds.

They made great jalopies for the young and it is probably in that context that most people would remember them. If not physically at least through movies and television shows. The were a real thrill and it is probably why the original owners flocked to get one. As they had never seen anything better they probably did not mind the inconveniences.

"The early Model T Ford revolutionized the automotive industry with the introduction of assembly-line production, which in turn made it possible for Ford to offer their car for sale at a much more affordable price. Prior to the introduction of the Model T, automobiles were built by hand, one at a time, and usually sold for anywhere from twice the average worker's salary to several times that amount."

History of Cars Part B

Veteran Era (1888 - 1904)

"The first production of automobiles was by Karl Benz in 1888 in Germany and under license to Benz, in France by Emile Roger. By 1900 mass production of automobiles had begun in France and the United States. The first company to form exclusively to build automobiles was Panhard et Levassor in France. Formed in 1889, they were quickly followed by Peugeot two years later. In the United States, brothers Charles and Frank Duryea founded the Duryea Motor Wagon Company in 1893, becoming the first American automobile manufacturing company. However, it was Ransom E. Olds, and his Olds Motor Vehicle Company (later known as Oldsmobile) who would dominate this era of automobile production. Its large scale production line was running in 1902. Within a year, Cadillac, Winton, and Ford were producing cars in the thousands (formed from the Henry Ford Company).

"Within a few years dizzying assortments of technologies were being produced by hundreds of producers all over the western world. Steam, electricity, and gasoline-powered autos competed for decades, with gasoline internal combustion engines achieving dominance in the 1910s. Dual and even quad-engine cars were designed, and engine displacement ranged to more than a dozen liters. Many modern advances, including gas / electric hybrids, multi-valve engines, overhead camshafts, and four-wheel drive, were attempted and discarded at this time."

In 1895 a patent was granted to a USA manufacturer, Sheldon, but it may have hindered the industry in that country rather than helped it. By granting a license to successive car manufacturers afterward he collected a fee on every car produced. Well, that was probably a good business outcome for him.

There were great handicaps to motoring in those times. The roads were bad, fuel was scarce, breakdowns were frequent, and the noise of a horseless carriage frightened the hacks pulling buggies around.

Restoring one of these vehicles is fraught with difficulties. Parts are not available and usually must be hand made or located with great effort. But that has not stopped collectors from coveting them and many are restored to their former glory. At one stage there were over a thousand manufacturers in the USA alone making the task even harder.

Caster , Camber , Toe in & out

THE EFFECTS OF CASTER

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if it's tilted forward, then the caster is negative.

Positive caster tends to straighten the wheel when the vehicle is traveling forward, and thus is used to enhance straight-line stability. The mechanism that causes this tendency is clearly illustrated by the castering front wheels of a shopping cart (above). The steering axis of a shopping cart wheel is set forward of where the wheel contacts the ground. As the cart is pushed forward, the steering axis pulls the wheel along, and since the wheel drags along the ground, it falls directly in line behind the steering axis. The force that causes the wheel to follow the steering axis is proportional to the distance between the steering axis and the wheel-to-ground contact patch-the greater the distance, the greater the force. This distance is referred to as "trail."

Due to many design considerations, it is desirable to have the steering axis of a car's wheel right at the wheel hub. If the steering axis were to be set vertical with this layout, the axis would be coincident with the tire contact patch. The trail would be zero, and no castering would be generated. The wheel would be essentially free to spin about the patch (actually, the tire itself generates a bit of a castering effect due to a phenomenon known as "pneumatic trail," but this effect is much smaller than that created by mechanical castering, so we'll ignore it here). Fortunately, it is possible to create castering by tilting the steering axis in the positive direction. With such an arrangement, the steering axis intersects the ground at a point in front of the tire contact patch, and thus the same effect as seen in the shopping cart casters is achieved.

The tilted steering axis has another important effect on suspension geometry. Since the wheel rotates about a tilted axis, the wheel gains camber as it is turned. This effect is best visualized by imagining the unrealistically extreme case where the steering axis would be horizontal-as the steering wheel is turned, the road wheel would simply change camber rather than direction. This effect causes the outside wheel in a turn to gain negative camber, while the inside wheel gains positive camber. These camber changes are generally favorable for cornering, although it is possible to overdo it.

Most cars are not particularly sensitive to caster settings. Nevertheless, it is important to ensure that the caster is the same on both sides of the car to avoid the tendency to pull to one side. While greater caster angles serve to improve straight-line stability, they also cause an increase in steering effort. Three to five degrees of positive caster is the typical range of settings, with lower angles being used on heavier vehicles to keep the steering effort reasonable.

Like a shopping cart wheel (left) the trail created by the castering of the steering axis pulls the wheels in line.

WHAT IS CAMBER?

Camber is the angle of the wheel relative to vertical, as viewed from the front or the rear of the car. If the wheel leans in towards the chassis, it has negative camber; if it leans away from the car, it has positive camber (see next page). The cornering force that a tire can develop is highly dependent on its angle relative to the road surface, and so wheel camber has a major effect on the road holding of a car. It's interesting to note that a tire develops its maximum cornering force at a small negative camber angle, typically around neg. 1/2 degree. This fact is due to the contribution of camber thrust, which is an additional lateral force generated by elastic deformation as the tread rubber pulls through the tire/road interface (the contact patch).

To optimize a tire's performance in a corner, it's the job of the suspension designer to assume that the tire is always operating at a slightly negative camber angle. This can be a very difficult task, since, as the chassis rolls in a corner, the suspension must deflect vertically some distance. Since the wheel is connected to the chassis by several links which must rotate to allow for the wheel deflection, the wheel can be subject to large camber changes as the suspension moves up and down. For this reason, the more the wheel must deflect from its static position, the more difficult it is to maintain an ideal camber angle. Thus, the relatively large wheel travel and soft roll stiffness needed to provide a smooth ride in passenger cars presents a difficult design challenge, while the small wheel travel and high roll stiffness inherent in racing cars reduces the engineer's headaches.

It's important to draw the distinction between camber relative to the road, and camber relative to the chassis. To maintain the ideal camber relative to the road, the suspension must be designed so that wheel camber relative to the chassis becomes increasingly negative as the suspension deflects upward. The illustration on the bottom of page 46 shows why this is so. If the suspension were designed so as to maintain no camber change relative to the chassis, then body roll would induce positive camber of the wheel relative to the road. Thus, to negate the effect of body roll, the suspension must be designed so that it pulls in the top of the wheel (i.e., gains negative camber) as it is deflected upwards.

While maintaining the ideal camber angle throughout the suspension travel assures that the tire is operating at peak efficiency, designers often configure the front suspensions of passenger cars so that the wheels gain positive camber as they are deflected upward. The purpose of such a design is to reduce the cornering power of the front end relative to the rear end, so that the car will understeer in steadily greater amounts up to the limit of adhesion. Understeer is inherently a much safer and more stable condition than oversteer, and thus is preferable for cars intended for the public.

Since most independent suspensions are designed so that the camber varies as the wheel moves up and down relative to the chassis, the camber angle that we set when we align the car is not typically what is seen when the car is in a corner. Nevertheless, it's really the only reference we have to make camber adjustments. For competition, it's necessary to set the camber under the static condition, test the car, then alter the static setting in the direction that is indicated by the test results.

The best way to determine the proper camber for competition is to measure the temperature profile across the tire tread immediately after completing some hot laps. In general, it's desirable to have the inboard edge of the tire slightly hotter than the outboard edge. However, it's far more important to ensure that the tire is up to its proper operating temperature than it is to have an "ideal" temperature profile. Thus, it may be advantageous to run extra negative camber to work the tires up to temperature.

(TOP RIGHT) Positive camber: The bottoms of the wheels are closer together than the tops. (TOP LEFT) Negative camber: The tops of the wheels are closer together than the bottoms. (CENTER) When a suspension does not gain camber during deflection, this causes a severe positive camber condition when the car leans during cornering. This can cause funky handling. (BOTTOM) Fight the funk: A suspension that gains camber during deflection will compensate for body roll. Tuning dynamic camber angles is one of the black arts of suspension tuning.

UNDERSTANDING TOE

When a pair of wheels is set so that their leading edges are pointed slightly towards each other, the wheel pair is said to have toe-in. If the leading edges point away from each other, the pair is said to have toe-out. The amount of toe can be expressed in degrees as the angle to which the wheels are out of parallel, or more commonly, as the difference between the track widths as measured at the leading and trailing edges of the tires or wheels. Toe settings affect three major areas of performance: tire wear, straight-line stability and corner entry handling characteristics.

For minimum tire wear and power loss, the wheels on a given axle of a car should point directly ahead when the car is running in a straight line. Excessive toe-in or toe-out causes the tires to scrub, since they are always turned relative to the direction of travel. Too much toe-in causes accelerated wear at the outboard edges of the tires, while too much toe-out causes wear at the inboard edges.

So if minimum tire wear and power loss are achieved with zero toe, why have any toe angles at all? The answer is that toe settings have a major impact on directional stability. The illustrations at right show the mechanisms involved. With the steering wheel centered, toe-in causes the wheels to tend to roll along paths that intersect each other. Under this condition, the wheels are at odds with each other, and no turn results.

When the wheel on one side of the car encounters a disturbance, that wheel is pulled rearward about its steering axis. This action also pulls the other wheel in the same steering direction. If it's a minor disturbance, the disturbed wheel will steer only a small amount, perhaps so that it's rolling straight ahead instead of toed-in slightly. But note that with this slight steering input, the rolling paths of the wheels still don't describe a turn. The wheels have absorbed the irregularity without significantly changing the direction of the vehicle. In this way, toe-in enhances straight-line stability.

If the car is set up with toe-out, however, the front wheels are aligned so that slight disturbances cause the wheel pair to assume rolling directions that do describe a turn. Any minute steering angle beyond the perfectly centered position will cause the inner wheel to steer in a tighter turn radius than the outer wheel. Thus, the car will always be trying to enter a turn, rather than maintaining a straight line of travel. So it's clear that toe-out encourages the initiation of a turn, while toe-in discourages it.

With toe-in (left) a deflection of the suspension does not cause the wheels to initiate a turn as with toe-out (right).

The toe setting on a particular car becomes a tradeoff between the straight-line stability afforded by toe-in and the quick steering response promoted by toe-out. Nobody wants their street car to constantly wander over tar strips-the never-ending steering corrections required would drive anyone batty. But racers are willing to sacrifice a bit of stability on the straightaway for a sharper turn-in to the corners. So street cars are generally set up with toe-in, while race cars are often set up with toe-out.

With four-wheel independent suspension, the toe must also be set at the rear of the car. Toe settings at the rear have essentially the same effect on wear, directional stability and turn-in as they do on the front. However, it is rare to set up a rear-drive race car toed out in the rear, since doing so causes excessive oversteer, particularly when power is applied. Front-wheel-drive race cars, on the other hand, are often set up with a bit of toe-out, as this induces a bit of oversteer to counteract the greater tendency of front-wheel-drive cars to understeer.

Remember also that toe will change slightly from a static situation to a dynamic one. This is is most noticeable on a front-wheel-drive car or independently-suspended rear-drive car. When driving torque is applied to the wheels, they pull themselves forward and try to create toe-in. This is another reason why many front-drivers are set up with toe-out in the front. Likewise, when pushed down the road, a non-driven wheel will tend to toe itself out. This is most noticeable in rear-drive cars.

The amount of toe-in or toe-out dialed into a given car is dependent on the compliance of the suspension and the desired handling characteristics. To improve ride quality, street cars are equipped with relatively soft rubber bushings at their suspension links, and thus the links move a fair amount when they are loaded. Race cars, in contrast, are fitted with steel spherical bearings or very hard urethane, metal or plastic bushings to provide optimum rigidity and control of suspension links. Thus, a street car requires a greater static toe-in than does a race car, so as to avoid the condition wherein bushing compliance allows the wheels to assume a toe-out condition.

It should be noted that in recent years, designers have been using bushing compliance in street cars to their advantage. To maximize transient response, it is desirable to use a little toe-in at the rear to hasten the generation of slip angles and thus cornering forces in the rear tires. By allowing a bit of compliance in the front lateral links of an A-arm type suspension, the rear axle will toe-in when the car enters a hard corner; on a straightaway where no cornering loads are present, the bushings remain undistorted and allow the toe to be set to an angle that enhances tire wear and stability characteristics. Such a design is a type of passive four-wheel steering system.