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When did leaf springs appear in vehicles?

When did leaf springs appear in vehicles?

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Passenger vehicles require suspensions for ride comfort. Most today use helical springs, but leaf springs were at one time a major advance over chain or leather strap suspensions, and are still used in some applications today.

Metal springs for vehicles predate the Bessemer process. Making a leaf spring starts with forging a thin, curved piece of metal. Making a superior one calls for a smart cooling schedules (e.g. initial quench, then slow cooling) and a careful choice of materials.

When did they appear in the historical record?

Leaf spring was first adapted to the horse drawn carriage in the 14th or 15th century. It didn't see widespread use until it's production became more practical in the 18th century. It cannot be said when "every" modern smithy was capable of producing Leaf Spring as each had it's own specialization as it were. I highly doubt you could walk into any smithy and ask for leaf spring at any point in history. You would have to visit what's called a "wheelwright" in the US. The only items I can safely say would be made in all smithy's are the common place and easily produced, IE nails, horse shoes.

To answer the question in the title, apparently the leaf spring was invented in 1804 by Obadiah Elliott, a carriage builder in London, who was granted a patent for his leaf-spring-suspension vehicle on 11 May 1805.

The following extract from Leaf springs, their characteristics and methods of specification; a hand-book of useful information relating to automobile leaf springs, their manufacture, methods of specification, details and characteristics has a little more detail.

Obadiah Elliott, a noted English carriage builder of Lambeth, obtained a patent in 1804 for a means of suspending vehicles on elliptic springs. The Society of Arts awarded him their gold medal and the popularity of his product, and his success in general, were doubtless prompted by this official recognition of merit.

Making a leaf spring starts with…

A leaf spring is a spring with many leaves (or laminae) bound together. Typically made of steel (but in principle other materials could have been used, e.g. laminated wood)

When did they appear in the historical record?

According to The Steel Spring Suspensions of Horse Drawn Carriages (circa 1760 to 1900) by Gordon S Candle B.Sc., Ph.D., M.Sc., C.Eng, M.I.Mech.E. 1978:

Although there had been earlier instances of their use, it was only from about 1770 that the inclusion of laminated steel springs began to be regarded as normal practise.

Steel was commercially produced before the Bessemer converter by a "puddle" process. Replacing the puddle workers with the Bessemer process lead to the Homestead (Pinkerton) riot.

Good spring steel is more than low carbon. It also requires alloying with larger metal constituents to pin the metal polycrystals in place.

History of the First Truck: 1896

The first truck in the world was designed by Gottlieb Daimler in 1896.

One of the greatest talents of inventor and German engineer Gottlieb Daimler was finding new areas of application for his engine. He invented the motor cycle, then went to the motorized trolley car, and a motorized firefighting hose. In 1896, almost inevitably, Daimler invented the truck, according to Daimler.

The first truck in the world looked like a cart with an engine and without a drawbar. The engine, called "Phoenix", was a four-horsepower-strong two-cylinder engine located at the rear, with a displacement of 1.06 liters, originating from a car. Daimler linked it to the rear axle by means of a belt.

There there were two helical springs to protect the engine, which was sensitive to vibrations. The vehicle rolled on hard iron wheels. Daimler steered the leaf-sprung front axle by means of a chain. The driver sat up front on the driving seat as with a carriage. The engine was at the rear of the vehicle. The fuel consumption was approximately six liters of petrol per 100 kilometers. In the terminology of the day, that would be "0.4 kilogrammes per horsepower and hour".

It is noteworthy that the first truck already anticipated 125 years before the planetary axles that are still common today in construction vehicles: because the belt drive sent the power from the engine to a shaft fitted transversely to the longitudinal axis of the vehicle, both ends of which were fitted with a pinion.

Each tooth of this pinion meshed with the internal teeth of a ring gear which was firmly connected with the wheel to be driven. This is how the planetary axles of the heavy Mercedes-Benz Trucks up to the current Arocs series have worked in principle.

In 1898, Gottlieb Daimler and Wilhelm Maybach shifted the two-cylinder Phoenix engine of the six-hp vehicle, which had been located at the rear, to a position under the driver's seat, with the four-gear belt drive also being transferred forward. However, this solution still left a certain amount to be desired.

In 1898, Gottlieb Daimler and Wilhelm Maybach shifted the two-cylinder Phoenix engine of the six-hp vehicle, which had been located at the rear, to a position under the driver's seat.

In the same year, the truck was then given the face which clearly distinguished it from the car and was to level the path towards ever-increasing output and payload: the engine was then placed right at the front, in front of the front axle. It conveyed its ten horsepower via a four-gear belt drive and a front-to-rear longitudinal shaft and pinion to the internal ring gears on the iron wheels at the rear.

For these vehicles, Daimler made the crucial improvement not only to the drivetrain, but to the engine itself. Instead of a hot tube ignition, the new low-voltage magnetic ignition from Bosch ignited the petrol-air mixture in the cylinders of the 2.2L two-cylinder engine, and the radiator had a completely new design.

According to reports, Daimler &ndash probably because of the large number of innovations &ndash was cautious at first before presenting his new five-tonner to the public. The vehicle which was highly modern at the time underwent "Customer testing" which is how the test procedure would be called today. For months, Daimler subjected his new five-tonner to the daily grind of work at a brick factory in Heidenheim, and he painstakingly remedied the shortcomings it showed.

The first purchaser of the very first truck came from the home of industrialisation: England. There, steam-driven vehicles had long since made the shift from rails to the road, and did not die out until the 1950s. It was a good thing that the Red Flag Act was abolished in 1896. Nevertheless, it was not until 1901 that a truck proved itself to be superior to a contemporary steam-driven wagon in a comparison test carried out in Liverpool.

The Daimler truck was a welcome guest in Paris, too. Daimler undertook the long journey to vibrant Paris to publicise his new product at the world exhibition. There, an automobile show was held in the Tuileries park, following a contest organised by the Automobile Association of France on the subject of "motorised vehicles for city travel" at the exhibition, Gottlieb Daimler presented his new five-tonner and a four-horsepower-strong belt-driven vehicle. "Huge crowds of people, many vehicles of all kinds and our truck are very popular," Daimler's wife Lina noted with satisfaction in June 1898.

The Daimler Manufacturing Company (DMFG) was an American production company from 1898 to 1907. From 1888 to 1898, the company was known as the Daimler Motor Company (DMC), founded as part of a partnership between Gottlieb Daimler of the Daimler-Motoren-Gesellschaft and William Steinway of the piano manufacturers Steinway & Sons. The company, with its headquarters in Long Island City, Queens, New York City, close to the headquarters of Steinway in Astoria, sold Daimler engines for yachts and launches as well as for commercial vehicles such as buses and trucks.

The second generation of Daimler trucks manufactured from 1899 to 1903 consisted of new basic types with a payload of between 1.25 and 5.0 tonnes, for which two-cylinder and four-cylinder engines from four to twelve horsepower were sufficient.

In detail, the almost complete range of the DMG in 1905 comprised: light vans with three payload classes from 500 kg 1000 kg to 1500 kg payload, powered by two-cylinder engines with eight to sixteen hp. Four-cylinder engines with 16 to 35 hp powered the heavy-duty class with two to five tonnes payload.

The "Roots" Of Supercharging

In the Beginning
Back in my school days, history was never one of my strong points. Like many of you, auto shop was my main interest and I paid much more attention to that than anything else--well, almost anything else anyway. Now that I'm youthfully challenged I find I'm spending more time reflecting on the past. So when we got together and drew out a game plan for this issue and decided on an engine performance focus, I decided to put some of that reflective effort into investigating the origins of supercharging. With this goal in mind, I retreated to the confines of my office and the wonders of the Internet to delve into the past and see what I could find. I have to admit that upon first glance some of the info didn't seem relevant at first. But as I continued, it kind of all came together. Without further adieu here's some of what I learned. I hope you find it as interesting as I ultimately did.

Way back in 1878 Paris, a gent by the name of Dr. Nicholaus Otto successfully built and demonstrated the first four-stroke internal combustion engine. This development instigated huge interest and spurred others to experiment with, build, and make improvements of their own. By 1896 Rudolf Diesel had filed his first patent for using a supercharger with his compression ignition engine (the first diesel engine), and in 1901 Sir Dugald Clark discovered that if he used a device to artificially increase the volume of air charge entering a four-stroke engine, it produced substantially more power. Right around the same time, back in France, a dude named Rateau developed the centrifugal compressor, and a guy named Renault patented a centrifugal fan, which blew air into the mouth of a carburetor. It was all happening very quickly.

In 1907, back here in the good old U.S. of A., Lee Chadwick, working with J.T. Nicholls, developed the idea of pressurizing an engine's carburetor to increase volumetric efficiency. Initially, they used an 8-inch diameter, single-stage centrifugal compressor driven at five times engine speed by a belt from the flywheel. It worked well beyond their expectations, but like any gearhead worth their salt, they craved even more power. To this end, they decided to install a three-stage blower driven at six times engine speed. The new, improved blower utilized three impellers, each with twelve blades, all of 10-inch diameter but of different widths. This hot-rodded compressor provided three-stage compression, which fed the carburetor with even more pressurized air. Things were definitely starting to get interesting!

Here's an early image of what started it all: the Otto designed internal combustion engine. In 1878, Otto successfully demonstrated the first four-stroke engine. He invented it barely two years earlier, though the actual concept belonged to Beau de Rochas who came up with the idea in 1862.

In May of 1908, Chadwick entered his car in the Great Despair hill climb in Pennsylvania and won. It's believed that this was the first competitive event in which a blown car was entered, never mind the winner. Over the next two years, the car dominated lots of events, the most notable being the 200-mile road race at Fairmont Park in 1910. Chadwick produced 260 replicas of this car, which had a top speed of over 100 mph, and sold them to the public, making the Chadwick the first publicly available vehicle to exceed that speed. Supposedly, Chadwick had considered an exhaust-driven centrifugal supercharger (that is, a turbocharger) before deciding on the belt-driven type.

Meanwhile, back in Europe, in 1911 and 1912 Sizaire and Birkigt, again in Paris, were experimenting with centrifugal blower- and piston-type compressor designs, as well. Birkigtt designed a Hispano Suiza-based engine, which used two of its six cylinders to supercharge the other four. That is, essentially a four-cylinder engine with a built-in two-cylinder compressor for supercharging. From what I gather, that experiment wasn't very successful.

Aviation Realizes the Benefits of Supercharging
During the course of World War I, supercharger development went a lot further with its use in aircraft engines in the continuous attempts to gain altitude for early fighters and bombers. Initial developments centered on the "Roots"-type positive displacement blower, but the potentially more efficient centrifugal compressor quickly replaced this. Because of the need for the high speed of the compressor, step-up geardrives had to be used. There were a lot of problems with these early systems, mainly due to rotational inertia. Spring drives, flex drives, fluid couplings, and centrifugal clutches were all tried at one point or another.

The main line of development of aircraft superchargers in Europe continued with mechanical drive. The Rolls Royce aircraft engine set the trend for a long line of engine developments by using a three-speed gearbox system to drive a two-stage centrifugal supercharger. In the Americas, the use of geared centrifugal compressors for aircraft engines was altered around 1925 as a result of General Electric's development of a practical turbocharger.

Back to the Blacktop
Following a lapse of 12 years since Chadwick's work back in the United States, the Duesenberg engine appeared in 1924 and won the Indianapolis 500 race. It had a two-litre engine with a centrifugal compressor, installed with the impeller at right angles to the line of the crankshaft. This was the first supercharging system to suck air through the carburetor, and subsequently showed an improvement when compared with positive displacement blowers, due to fuel cooling. There also began the widespread use of alcohol fuels in racing. With the exception of Mercedes, who persisted in downstream carburetor positioning until 1937, the practice of mounting the carburetor in front of the supercharger became normal.

From 1925-38, the Grand Prix formula led to the supercharging of virtually all racing engines there was a steady increase in power, coupled to increased boost pressures and the use of alcohol fuel. By 1938-39, Grand Prix racing was completely dominated by the enormously powerful Mercedes and Auto Union cars. The Auto Union contender had a six-litre engine delivering 520 hp at 5,000 rpm, running on methanol fuel, with a compression ratio of 9.2: 1, and a boost pressure of 1.8-bar. The Mercedes M125 produced 646 hp. Both Mercedes and Auto Union used two-stage supercharging with Roots blowers, and in 1939 were getting up to 2.65-bar pressure on three-litre engines.

Known by various names Italmeccanica, I. T. Superchargers, S.Co.T. - Supercharger Company of Turin (Torino), Italy was one of the most popular "Roots"-style blower kits available in the 1950s.

After World War II, when European racing finally resumed, Formula 1 Grand Prix was 4.5 liters un-supercharged or 1.5 liters supercharged, and many of the pre-war supercharged designs competed successfully. In 1950-51, the non-supercharged Ferrari engine became dominant and the decline of the supercharged cars started. The only significant attempt to continue with supercharging came with the ill-fated V-16 BRM car, which used a Rolls Royce aircraft-type, two-stage centrifugal supercharger. At 5,000 rpm, the 1.5-litre engine produced only 100 hp, but at 8,000 rpm it jumped to a more than respectable 330 hp, backed by a similar, rapidly rising torque curve--a combination that must have made it quite a handful to drive!

The period between the two World Wars was the heyday of supercharging. Not only did the major racecars of the time run blowers but, as you might expect, so did several of the more racy production models, both here and in Europe. However, the economic Depression and then WW II finally put an end to supercharged luxury sports cars and, shortly after war's end, the changing of rules put a stop to the supercharger's advantage in racing. Consequently, after the 1940s, superchargers virtually disappeared from the automotive scene.

The Progressive Engine Products Company (PEPCO) designed and marketed PEPCO supercharger kits in the United States beginning around 1950. These "Roots"-type blowers were simple, efficient, reliable, and designed to rev up to 8,000 rpm. Employees at Lou Fageol's Porsche dealership, Emmer Kelley and Arthur Hilf designed and put into production these wonderful compressors. Shortly after their introduction, PEPCO superchargers were manufactured and distributed by Fageol Products, 789 Stow St., Kent, Ohio

Leave it to the hot rodders
It was just before and after World War II that hot rodding really began to exist. The youngsters who raced stripped-down Model Ts and As on dirt ovals and dry lakebeds were a far cry from the sophisticated European Grand Prix and U.S. Indy race car builders. But they'd been paying close attention to the way the pros built race engines and they knew superchargers made horsepower. In the hot rodding world there was no restriction on blowers the major hurdle then was cost.

Even though, there were still a few early examples of blowers being run on the lakes, even in the Depression days before the war. A few rodders snagged centrifugal blowers from production American cars like the Graham, and adapted them to the Ford flathead V-8. However, Graham blowers produced meager boost and when anyone tried to spin 'em faster to get more pressure they usually ended up tearing up the blower's drive gears. Around that time McCulloch introduced a centrifugal supercharger as an aftermarket bolt-on kit for the Ford V-8 (most likely the first aftermarket blower kit), and some of the more bucks-up builders tried them at the lakes.

The first example that I found of a Roots-type blower being fitted to a hot rod was in the late '30s when the Spalding Brothers scoffed up a Mercedes Benz blower and put it on their flathead Ford. After the war, Don Blair bought this blower from the Spaldings and adapted it to his unlimited-class roadster for the 1946-47 seasons. Running alcohol through two Stromberg 48s, and driving the blower with two V-belts--the car turned 141 mph.

The person usually credited with the first installation of a Jimmy (GMC) blower on a hot rod was Barney Navarro. Barney had been aware of blowers for some time, but they were scarce and expensive. Then one day in 1948, Kong Jackson showed up with a 3-71 GMC off a World War II landing craft, and offered it to Navarro for $60. Barney was manufacturing his own line of V-8 heads and intake manifolds at the time, so he modified one of his manifold patterns to fit the blower and cast an intake manifold for it. He built his own drive using four V-belts and mounted four Stromberg 48 carbs on top of the blower to run alcohol through a de-stroked, 176-cube V-8 in his '27 roadster. This setup made around 16 pounds of boost and pushed the car to 147 mph. The only internal modification that Barney made to the blower was to bore the case slightly larger for increased rotor-to-housing clearance so he could really wind it out.

Barney not only ran the roadster at lakes, but also raced it on the dirt circle tracks, possibly the only supercharged hot rod to do so. And though he never had any serious mechanical problems with the blower itself, the V-belt drive drove him nuts since they had a tendency to heat up and disintegrate. Barney finally overcame this malady by drilling a bunch of holes through the pulleys to help keep the belts cool.

This shot's from March of 1961. It's an image of a Hemi-headed small-block Chevy on Isky's dyno for a bit of tuning. This engine made 638 hp with a 301ci small-block, a 6-71 blower, an Isky cam, a Vertex mag, and a two-port Hilborn injector on alcohol.

Tom Beatty, who worked for Navarro, built a similar system for his own lakes roadster, adapting a 4-71 GMC to an Oldsmobile OHV V-8 for his belly tank lakester. Beatty eventually manufactured manifolds and drive "kits" for the Jimmys, based on the Navarro V-belt design, and helped pioneer the more widespread use of GMC blowers. In fact, Beatty once stuffed one of his blown race engines into his '40 Ford sedan delivery to use as a street driver and push truck.

Supposedly, Navarro was also one of the first to run a blower at the drag races, since he entered his roadster at the first running of the Santa Ana drags in 1950. However, Barney did not pursue drag racing with a blown engine because he kept blowing quick changes to pieces.

Into the '70s and Beyond
As far as supercharging for the majority of street cars are concerned, the history is rather brief. After the prestigious supercharged road cars of the '20s and '30s, the next appearance of blowers was a handful of bolt-on supercharger kits that suddenly appeared on the market about 1950. These included the McCulloch, the Frenzel, the S.COT/Italmecanica, a few assorted blower kits based on reworked GMC 3-71s or 4-71s like the J.E.M. and Speed-a-Motive offerings, and later the Judson and Latham superchargers. Then, in the mid-'50s after Chevrolet introduced its new small-block V-8, Ford and other manufacturers suddenly found themselves in the position of playing catch up. Since Ford's new V-block was no match for the Chevy, Ford turned to supercharging as one way to beat those darn Chevys on the NASCAR tracks and on the beach at Daytona. They recruited McCulloch to design a special centrifugal blower for the racing Fords, and then offered the standard McCulloch variable-speed, belt-driven blower as optional equipment on '57 Fords and T-Birds. The same year Studebaker offered the McCulloch on their Golden Hawks and on some of the last Packard models. As late as 1963, the McCulloch/Paxton was used as standard equipment on the Studebaker Avanti.

Here's an image of "Big John" Mazmanian's blown '61 Vette. This supercharged beauty turned low 11s at 130 mph back in 1962!

From this time on, however, Detroit turned to the turbocharger for supercharging production models. Through the '60s and early '70s, there were isolated examples of supercharged street-driven hot rods, but most of these were way out of the norm. The sight and sound of a working GMC blower on the street, not to mention the potential power they provided was exciting to say the least. But GMC blowers were scarce, parts to adapt them to a street engine were nearly non-existent, and getting one to work right in traffic took lots of trial and error.

Within the last couple of decades, however, blowers have come of age for street machines. People have discovered that, with proper clearances, bearings, and drive ratios, there is no reason why a Roots-style blower should be any "hassle" on the street. First, a variety of companies offered complete drive kits for Jimmies on street motors--which incorporated water pumps, fans, alternators, and so on. Then, a couple of companies started fabricating or modifying blower manifolds to fit street motors other than small-block Chevys and Hemis. Heck, these days you can choose from a variety of complete bolt-on street-blower kits, including polished and ready-to-run blowers, manifolds, drive assemblies, carbs, and everything else you might need. In addition, several companies have recently introduced new superchargers and installation kits designed specifically for street performance engines--many designed to work directly with today's electronically controlled fuel-injected engines, producing big power gains with virtually no other engine modifications. And finally, with advances in design and efficiencies, we are seeing factory/OEM availability of belt-driven superchargers for the first time since the 1950s. Supercharging is indeed alive and well.

How automobile bodies evolved through history from wood to carbon fiber

Steve Jobs enjoyed driving powerful luxury cars. Could this have been the early inspiration for Apple to get involved with autonomous automobiles?

Another creative genius, Frank Lloyd Wright, also enjoyed fast and beautiful vehicles. He tried designing a few, but he had better success as an architect than as a carchitect. At the time he practiced his art, the automobile was in its infancy. Cars were crafted from wood, just as horse-drawn wagons had been constructed for hundreds of years. Heavy they were, but weight did not matter at a time when fuel was inexpensive and plentiful.

Today, the auto industry is shedding weight wherever it can to improve fuel consumption and lessen emissions. New materials are helping designers and engineers to accomplish that objective. Why then is it a good thing that we praise carbon frames and carbon body panels when we condemn carbon fuel? That's a 'weighty' question.

It had started with wood. Why would wood not be the choice material in the early automobiles, when it was well known for centuries in wagons wheels and cherished chariots of all types. When horseless carriages were converted into 'auto-buggies', they retained their wood frame. Skilled craftspersons also created the body structures. These were covered with treated canvas, before being painted. (BTW, that feature is making a modern comeback.)

As in every occupation, people experimented: Some cars were built differently, using diverse materials: Already the Model T combined wood and metal a Hanomag of the 1920s had a wicker body the budget version of the steel version.

Even when steel frames were used, many manufacturers sent the running gear (called 'chassis', from French) to coachbuilders to complete the automobile by fitting a wood body to the frame. Boat builders were skilled in this type of work, and the style of car we still know today as a ' boat-tail' is a holdover from that era.

As the automobile matured, fewer skilled craftspersons were on hand, and steel and aluminum panels were used to cover the wood-framed body. Already during the second decade of the last century, forward-thinking individuals were envisioning a better way to make automobiles. During a lecture at an early meeting of the Society of Automotive Engineers (SAE), someone interrupted the presenter H. Jay Hayes by asking, "What do you think about the controversial theory of combining the body and frame into one unit?"

He surprised his audience by announcing that his coach-building company would produce 3,000 cars just like that, starting the week after the SAE conference, named the Ruler Frameless. Hayes explained the advantages of a combined frame and body unit: making the car smaller and lighter, reducing cost and vibration.

It was difficult for automakers to abandon the frame, and complicated to produce cars in that radical new way. It took many years before one of the mass-producers attempted to fabricate a unibody. 'Unibody' is also known as 'monocoque' (from the Greek mono (single) and the French coque, meaning shell.)

In the meantime, frames made progress in their own right new alloys were developed, ladder frames advanced into perimeters frames the X-frame improved roll-stiffness for better handling, and so on.
The first popular mass-produced unibody car came in 1928 from DKW (now Audi) with a fabric-covered wood frame. Today, Audi builds cars with an aluminum ' spaceframe'. The Chrysler Airflow and the Citroen Traction Avant of 1934 used stressed body panels, and the Opel Olympia of 1935 was General Motors' first unibody car.

The Volkswagen Beetle had a platform frame to which the body attached, making it extremely stiff. An additional benefit of the platform frame made it possible to adopt different body shapes, the early Porsche, Karmann Ghia, the VW 'Micro Bus', dune-buggies, and others.

Most pickup trucks, vans, and SUVs of today still use a body-on-frame construction, while the ' crossovers' are frameless. Honda's Ridgeline is a unibody exception. Manufacturing cars that way is almost universal today.

Open-wheel racecars (IndyCars and Formula 1) and prototype sports cars ( Le Mans type) have gone a step further in monocoque construction. Through the marvels of modern chemistry, the body of these cars is stronger than steel and lighter than aluminum.

Fiberglass cars (and boats) have proven their advantage over many years, but compared to mass-produced cars, their numbers are still small. Because of the urgent need to lower weight and fuel consumption, and thereby emission, modern cars utilize innovative materials, stronger and lighter than fiberglass, namely carbon fiber.

You may know that fiberglass takes hours to 'cure' or harden. Efforts are underway to 'bake' carbon fiber and resin combinations in autoclaves to reduce manufacturing times to less than six minutes. Under high pressure and temperature, resin is injected into the mold where a cloth-like weave of carbon and other fibers is placed. Variations of the chemical ingredients dictate whether a composite part is flexible or rigid – leaf springs are produced from fiberglass regularly.

After all the progress, wood still has a place in many motorists' mind: the eternal popularity of the 'Woodie'. Even recent engineering students are exploring the strengths of wood and others fibers when they built the 'Splinter' supercar. Long live the Woodie!

As newer fuel efficiency rules and CO2 restrictions are pending, many manufacturers prepare to mass-produce major components and complete unibody vehicles from carbon fiber composites. Stronger than steel, but less than half the weight, these new cars are 'paving the road' for zero emission electric vehicles.

New styles with good performance and efficiency are surpassing cars of the ICE (internal combustion engine) age they will assure sustainable personal mobility for millions of future motorists in the current r EVolution of the automobile.

The Anatomy of the Landing Gear

Snorri Gudmundsson BScAE, MScAE, FAA DER(ret.) , in General Aviation Aircraft Design , 2014

Leaf-spring Landing Gear (A)

The leaf-spring landing gear, as the name implies, consists of a relatively flat but stiff cantilever beam that reacts landing loads in bending. The primary advantage of such landing gear is that it is inexpensive, stout, durable, and is relatively easy to mount to an airplane. It really represents the simplest form of the landing gear. The leaf-spring landing gear is generally used as the main landing gear. Its relatively low thickness-to-chord ratio renders it a relatively low-drag external structure, although the wheels, tires, and braking calipers generate substantial drag and should be covered using a wheel fairing. The primary drawbacks are high reaction loads in the airframe, as the spring beam tends to have a large moment arm. Also, the landing gear does not lend itself well to a retractable configuration. Some Cessna aircraft feature retractable cantilevered landing gear that resembles leaf-spring gear, but really consists of tubular geometry. The leaf-spring has limited structural damping, but works well because of the damping provided by the scrubbing motion of the tires. It has a poor efficiency as a shock absorber, something remedied by the scrubbing motion as well. To the best knowledge of the author, the largest aircraft to currently use a leaf-spring landing gear is the de Havilland of Canada DHC-6 Twin Otter, with a maximum gross weight of 12,500 lbf.

History and Identification of Chevy 10 and 12 Bolt Chevy Differentials

Chevy 10- and 12-bolt axle assemblies have been standard equipment on GM passenger cars, muscle cars, and trucks for decades. The rugged, reliable, and efficient Chevy 12-bolt has established itself as the preeminent rear differential for GM muscle cars since its debut in 1965. However, the smaller 10-bolt unfairly gained the reputation as a weak and inadequate rear end for high-performance applications. But there are several models in the 10-bolt line-up. The smaller 7.5- and 8.2-inch 10-bolt rear axles can’t transmit horsepower loads in excess of 400 hp. However, the 8.5- and 8.6-inch 10-bolts are extremely stout and effective rear differentials that can transmit up to 1,000 hp to the rear wheels.

This Tech Tip is From the Full Book, CHEVY DIFFERENTIALS: HOW TO REBUILD THE 10- AND 12-BOLT. For a comprehensive guide on this entire subject you can visit this link:

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The GM 10-bolt rear end is quite possibly the most misunderstood and undervalued rear differential ever created. Even though it has been used in every major GM rear-wheel-drive platform, the 10-bolt has a bad reputation for being a low-performance unit. Nothing could be further from the truth. The 10-bolt can handle just about anything you throw at it, as long as you use the right axle, either the 8.5- or 8.6-inch. That is the great caveat there are four sizes of 10-bolt GM rear ends: 7.5/7.625-, 8.2-, 8.5-, and 8.6-inch. These sizes refer to the diameter of the ring gear, and the one you use makes a big difference in the performance potential. The 8.5- and 8.6-inch provide superior performance and have a larger ring and pinion gear surface to handle high horsepower. Also, these surfaces run cooler because of their sheer size.

This is the Moser Engineering 12-bolt axle assembly. As you can see, the Chevy 12-bolt differential is one stout axle, and it was the rear axle of choice for GM muscle cars and many GM competition cars. Big-block Chevelles, Camaros, and other GM high-performance vehicles were fitted with the 12-bolt limited-slip axle to maximize torque transfer and traction. (Photo Courtesy Moser Engineering)

10-Bolt Identification

You need to be able to accurately identify the GM 10-bolt. Therefore, you need be able to choose the more desirable 8.5- or 8.6-inch and avoid the smaller 7.5/7.625- and 8.2-inch units. Identifying the 10-bolt axle is easy. The nomenclature actually refers to the number of ring gear bolts. The outer cover matches 10 bolts hold the cover onto the housing.

This ring-and-pinion gear has suffered catastrophic failure. Be sure the mesh is correct and that the installed parts are correct so you don’t destroy components. If you take off the center section cover and discover this kind of damage, you need to identify the cause so you don’t repeat this type of failure.

8.2-Inch Units

The key to identifying the 8.2 is the shape of the housing and the spacing between the lower bolts on the cover. The 8.2 has a smooth, round lower case area, with an 11-inch cover that has a diagonal indentation at the top or a 10 5/8 -inch irregular-shaped cover. The pinion nut should measure 1 1/8 inches, as long as it is the OEM pinion nut.

Inside the 8.2, the ring gear bolts have 9/16-inch socket heads with 3/8-24 threads. The pinion diameter is 1.438 inches with 25 splines. The axles are retained by a set of C-clips on the inner end of the axle shaft inside the carrier.

8.5-Inch Units

Most 8.5-inch 10-bolts have two lugs on the bottom of the housing at the 5 and 7 o’clock positions. These should be square blocks, each with the outer side 90 degrees (vertical) to the road and the bottom-side surface horizontal to the road. The covers are often 11 inches round with a bulge on the driver’s side for the ring gear or a 10 5/8 -inch irregular shape with the same bulge. The distance between the lower cover bolt and either adjacent bolt is 3 3/4 inches. The pinion nut is 1 1/4 inches.

The 8.5-inch differentials have 10 3/4 -inch hex head bolts with 7/16-20-inch left-hand thread or reverse-thread bolts that hold the ring gear to the carrier. The pinion shaft diameter is 1.625 inches with 28 or 30 splines, which is the same as the GM 12-bolt design. Most 8.5 10-bolts are C-clip axles, so a set of C-clips retains the inner end of the axle shaft inside the carrier.

Buick and Oldsmobile bolt-in axles mount at the bearing flanges on the housing ends. They retain the axle shafts in the event of a failure. The four bolts that hold the drum back plate on also retain the flange. Note that this axle has been converted to disc brakes.

Bolt-in axles include (right to left) the axle, retainer plate, split washer shim, press-on bearing, and housing end. To remove the axle shafts, you need to remove the four bolts.

The rear cover’s shape and the number of bolts are identifying features for GM rear differentials. The round 10-bolt cover with a bulge for the ring gear identifies this axle assembly as an 8.5-inch 10-bolt. The two lugs on the lower case at the 5 and 7 o’clock positions are also identifying features. The 8.2-inch differential does not have these lugs.

A pair of long flat areas on the front side of each axle tube is a clear indicator of an 8.5-inch Chevy 10-bolt.

To help you identify the 8.2-inch housing, remember that it may have an irregular-shaped cover or a round cover, but it does not have lugs as on the 8.5-inch.

A variant of this axle assembly was used in 1971–1972 Buick GSs and Skylarks, Oldsmobile Cutlasses, and some 1969–1972 Pontiac Grand Prixs, as well as the 1970–1972 Monte Carlos. These axle assemblies had bolt-in axles and were used sporadically in A-Body wagons as well. These are highly sought after, and as such, are hard to find. In this version, the axles bolt to the housing ends just as on a Ford 8- or 9-inch. This means that in the event of an axle break, the wheel stays on the car.

7.5/7.625-Inch Units

To positively identify the Chevy 10-bolt in the 7.5/7.625-inch size, you need to measure it because it is very similar to the 8.5-inch housing. The case has a similar pair of lugs at the base of the center of the housing, which are located at 5 and 7 o’clock. However, the 7.5-inch lugs are smaller, with the outer side running at an angle and the inner side cut with a radius. The oval-shaped cover measures 8 5/16 inches by 10 9/16 inches. The distance between the lower center cover bolt and its adjacent bolts is 3 1/4 inches. Inside, the ring gear bolts are the same as the 8.5 corporate unit. However, the pinion shaft measures 1.438 inches. The axles are retained by a set of C-clips on the inner end of the axle shaft inside the carrier.

Chevy 10-Bolt Models

Although the 8.5- and 8.6-inch rear axles are more than capable of handling 400 hp (and with some setups a bit more), the 10-bolt name has a bad reputation due to the inherently weaker 7.5 and 8.2 designs. Because these two sizes are so common in pre-1971 (8.2) and 1975– 2002 (7.5) vehicles, the 8.5 is lumped into the same group. This design was used in all GM rear-drive cars from 1964 through 1972. The 8.2 was phased out starting in 1971 it was replaced by the 8.5-inch “corporate” 10-bolt, and was installed in everything from Camaros and Chevelles until the mid-1980s. It remained in the 1/2-ton trucks until 1999, when the 8.6 replaced it, using the same basic design.

By far, the most common 10-bolt is the 7.5/7.6, and it has been around since 1975. It was installed on small trucks and vans up to the 2005 model year. There is very little aftermarket support for this axle assembly because it couldn’t handle high-horsepower loads and therefore its performance potential was marginal. In street applications, the 7.5 is good for 350 to 400 hp with street tires and lots of wheel spin. When sticky traction bars and/or sticky tires were installed, owners found that 400 hp can quickly turn the 7.5 into shrapnel.

In the final analysis, this axle is simply too small for high-horsepower cars, and so these axles should be avoided for most muscle cars and certainly any racing applications. Although gear sets and a locking differential are available, these are only suitable for a mild street engine or possibly a dirt track car. In the world of dirt track racing, some classes require a GM 7.5-inch 10-bolt and because there is no traction on dirt, this rear works very well.

Millions of 8.2-inch axle assemblies were built and many can be found in salvage yards. And like the 7.5 axle, it has a fair amount of aftermarket support but the ring gear is too small and therefore it cannot handle much torque. If installed on a 400-hp or stronger engine, it often fails. And unfortunately, there simply isn’t enough room to install bigger axles, so it isn’t a viable option for a high-performance car. To support high torque and horsepower loads, the axle shafts need a larger diameter and spline count. Combined with the small outer bearing races, the 8.2 is limited to 28-spline axles.

For performance vehicles, the 8.2 can typically handle up to 400 hp with street tires, but that’s the limit for this axle. If you bolt on even a set of drag radials, the axles bend or break, along with having the potential for breaking the gears and carrier themselves. You can build these for performance, but if you use sticky tires, the superior traction and consequent strain from the grip will kill it quickly on the drag strip.

There are temporary fixes for the 8.2, such as a carrier girdle, but they don’t provide a reliable and suitably strong solution. When too much torque or traction is fed through the axle, it will eventually break the axle.

The 8.5- and 8.6-inch 10-bolts have larger ring-and-pinion gears, which makes an important difference. These rear axle assemblies can handle up to 400 hp. Among the Chevy 10-bolt family of axles, these provide the best performance and durability. The car versions were in production from 1971 to 1987. General Motors has been using this axle assembly in cars for 16 years and in 1/2-ton trucks for 30 years. The 2010-up Camaro uses a similar design (8.6 10-bolt) in the center section of its independent rear suspension.

The 8.5 is limited to 30-spline axles, but can withstand 1,000 hp with slicks when properly built. The factory installed the 8.5-inch 10-bolt in the Buick Grand National, and that’s the biggest claim to fame for this OEM axle. In stock form, the 8.5 can support wheel-standing launches from the turbocharged 6-cylinder. At just 3/8-inch smaller than the 8.875-inch 12-bolt differential, the 8.5-inch ring gear is strong enough for high-performance applications.

The aftermarket fully supports the 8.5. Gears of all sizes, limited-slip or Posi-Traction, lockers, and spools are offered. Affordable performance is what the 8.5 is all about. Considering the challenges of the typical 12-bolt swap for most muscle cars, when the 10-bolt units are often a bolt-in swap, the 8.5 10-bolt starts to look really good.

10-Bolt Carriers

Several differential carriers are offered for the 10-bolt axle assemblies. However, only certain gear sets are offered for the carriers, especially if you change gear ratios. Typically, 10-bolt carriers are specific to a series of gears. A 2-Series carrier holds 2.56:1 and higher gears (numerically lower) such as 2.41. These are very high gears, good for top speed, not for off-the-line performance. The 3-Series carriers are good for 2.73 and lower gears, so 3.08 and 3.73 gears work well.

To help you identify the 8.2-inch housing, remember that it may have an irregular-shaped cover or a round cover, but it does not have lugs as on the 8.5-inch.

In this photo, you clearly see the clutch packs with springs, so indeed these are limited-slip differentials. A Yukon aftermarket clutch-type limited-slip differential is on the left the GM Posi-Traction differential from a 1971 Buick Gran Sport 8.5 10-bolt is on the right. As you can see, the Yukon casting is much thicker and so are the springs.

The stock axles for both Chevy 10- and 12-bolt differentials use C-clips unless you have one of the rare bolt-in axle units. A small bolt in the center of the carrier retains the crossbar.

The C-clips are not the strongest method for retaining the axle shafts many owners convert the Chevy 10- and 12-bolt axles to a flange type, which retains the axle if it fails. To remove the C-clip, you push the axle in to allow room to snag the C-clip with a pick. Once the C-clip has been removed, the axle slides out of the housing.

The placement of the casting numbers on an 8.2-inch 10-bolt varies by year and model. When you decode these numbers you can conclusively identify your axle.

Engine torque and suspension loads are placed on the rear axle assemblies, which are also subjected to moisture, dirt, and anything the road can throw at it. You may need to clean the rear housing before you can decode the casting numbers. You can simply clean the area around the casting pad, but a power washer and some hot soapy water can work wonders for 40 years of grime.

10-Bolt Housings by the Numbers

Before you rebuild any axle, you should identify which axle you have. Once you have identified the housing, you must order the correct parts for the particular axle. The casting numbers for 10-bolt rear differentials are typically located either on the forward side of the passenger-side axle tube or on the driver’s side. These numbers are approximately 3 inches from the center section.

The two examples at right show you how to decode 10-bolt housings.

1970 axle code: COZ 01 01 G E

1971+ rear axle code: CB G 112 1 E

10-Bolt Gears by the Numbers

Gears are also “coded” with their teeth count dividing the number of ring gear teeth by the number of the pinion gear teeth yields the ratio.

A full range of pinion gears is offered for the Chevy 10- and 12-bolt axle assemblies so you are able to select the correct gear set for your vehicle, application, and setup. These are two pinion gears for the 8.5-inch 10-bolt. The pinion on the left is part of a 4.11:1 gear set the one on the right is a 3.08:1 pinion. You can see the dramatic difference in not only teeth but in overall diameter.

A full range of pinion gears is offered for the Chevy 10- and 12-bolt axle assemblies so you are able to select the correct gear set for your vehicle, application, and setup. These are two pinion gears for the 8.5-inch 10-bolt. The pinion on the left is part of a 4.11:1 gear set the one on the right is a 3.08:1 pinion. You can see the dramatic difference in not only teeth but in overall diameter.

The tooth count is stamped on the head of each pinion for both the pinion and the ring gear. As you can see, 13 is the hypoid gear countfor the pinion and 40 is the ring gear count. Pinion gears and ring gears are not interchangeable because they are designed for the specific (correct) mesh. Therefore, the specified pinion and ring gears must be used together.

The tooth count is stamped on the head of each pinion for both the pinion and the ring gear. As you can see, 13 is the hypoid gear count for the pinion and 40 is the ring gear count. Pinion gears and ring gears are not interchangeable because they are designed for the specific (correct) mesh. Therefore, the specified pinion and ring gears must be used together.

12-Bolt Identification

When it comes to GM muscle cars and sports cars, the 12-bolt axle has been the top high-performance axle assembly for decades. Compared to the Ford 9-inch, the 12-bolt positions the pinion gear higher on the ring gear. This reduces the load on the pinion, resulting in less parasitic loss from the friction and load.

The 12-bolt was introduced in 1964 and installed in cars and trucks until 1972. From 1972-on, General Motors installed its 10-bolt in cars and it remained an option for trucks until 1987.

Unlike the various 10-bolts, the 12-bolt axle assembly has different components for cars and trucks. The passenger car 12-bolt has an oval-shaped differential cover, and it measures 10 15/16 x 10 5/8 inches.

This 1967 Chevy truck used a trailing-arm design with coil and leaf springs. The half-leaf spring (left) serves as an overload spring for heavy loads or trailering.

General Motors installed different axles for different applications. Axles for high-performance or heavy-duty applications commonly used higher spline-count axles while common passenger car axles use lower spline counts. The top axle is an 8.5-inch 10-bolt with 30 splines the bottom axle is an 8.5-inch with 28 splines. Note the thicker head on the bottom axle where the C-clip rides. This is specific to the carrier. The carrier and axles must match.

General Motors used several different suspension designs in their passenger cars throughout the 1960s and 1970s. This 8.5-inch 10-bolt came from a 1971 Buick GS. The large bushings at the top of the differential housing connect to the triangulated four-bar trailing arm system that the Buick used. It is more difficult to swap these housings from car to car if they do not share the same suspension design.

Camaros, Novas, and 1968 and later trucks used leaf springs like these. The axle may be over or under the leaf, depending on the application.

C2 and C3 Corvettes (built from 1963 to 1981) used a non-standard 10-bolt design. They used an independent rear suspension with transverse leaf springs. As a result, these cars use a specialized axle housing for this suspension, and it’s not easily upgraded. You need to machine the housing to accept a 12-bolt carrier, which also requires custom axles. Essentially, the housing is machined to clear the larger gears and carrier, and it’s not a job for the novice.

Trucks have a smaller inner pinion shaft (1.438 inches versus 1.675 inches) and bearing, and the pinion rides lower on the ring gear. In addition, the truck 12-bolt has an irregular shape. The early truck 12-bolts had large axle splines with only 12 splines. The differential carriers are also narrower than on the passenger car units, and they do not interchange. That does not mean that the truck units are not capable of performance builds because aftermarket 30-spline carriers and axles are available.

The truck 12-bolt axles are much more affordable than the car units because they are more plentiful but these units have fewer splines so they are not as strong as the axle in the car assemblies. In addition, the trucks typically have larger axles and brakes.

Most passenger car 12-bolts used a four-bar trailing arm mounting system, with the exception of the Camaro and Nova, which used leaf springs. GM trucks from 1961 through 1967 used a two-bar trailing arm mount, while the 1968-up trucks used leaf springs. There is some crossover on the trucks, as some earlier trucks had leaves and some later trucks had the trailing arms.

All GM 12-bolts use C-clip–style axles. Aftermarket 12-bolt housings are based on the passenger car design.

12-Bolt Carriers

The 12-bolt carriers also use the same series-specific system as do the 10-bolts each carrier only works with certain gear sizes. The types are 2-, 3-, and 4-Series. The 2-Series is by far the most common.

12-Bolt Housings by the Numbers

The casting numbers for the 12-bolt housings are typically found on the upper rear of the driver’s side of the center section. The casting numbers are simple to decode.

The first letter is the month of the year A is January, B is February, and so on. The next digit is the day it was built, and the last digit is the year it was built. For example, a 12-bolt axle that was built on March 28, 1967, is C287.

The Chevy 12-bolt axle assemblies for passenger cars feature an oval cover with a diagonal indentation. This is a 1969 Chevelle 12-bolt housing.

Truck 12-bolts have an irregular cover with a ring gear pocket. This example is a 1967 Chevy C10. The truck housings are not as durable as the passenger car housings due to a narrower carrier and a smaller inner pinion bearing.

On the passenger-side front tube, the stamped axle code designates either 1969-and-earlier units or 1969-and-later builds. The 1969- and-earlier codes have two letters, then a four-digit number, followed by a letter, and possibly a shift number, for which 1 is the day shift and 2 is the night shift.

And finally, a Posi-Traction number was used.

For 1969 and later, the code typically features six to eight digits, including three letters, three numbers, and sometimes an additional number and letter. The first two letters indicate the gear-ratio code, the third letter notes the build plant, and three numbers designate the build day from 001 to 365. Sometimes the shift code is stamped, and if the unit has a Posi-Traction, you see a P stamp.

Written by Jeferson Bryant and Posted with Permission of CarTechBooks


Development of the MGB started at least as early as 1958 with the prototype known by its Abingdon codename MG EX205. [4] In structure the car was a progressive, modern design in 1962, utilizing a unitary structure, instead of the traditional body-on-frame construction used on both the MGA and MG T-types and the MGB's rival, the Triumph TR series. [5] However, components such as brakes and suspension were developments of the earlier 1955 MGA, with the B-Series engine having its origins in 1947. The lightweight design reduced manufacturing costs while adding to overall vehicle strength. Wind-up windows were standard, and a comfortable driver's compartment offered plenty of legroom. A parcel shelf was fitted behind the seats.

The MGB achieved a 0–60 mph (97 km/h) time of just over 11 seconds. The three-bearing 1,798 cc B-Series engine produced 95 hp (71 kW) at 5,400 rpm – upgraded in October 1964 to a five-bearing crankshaft. From 1975, US-market MGB engines were de-tuned to meet emission standards, ride height was increased by an inch (25 mm), and distinctive rubber bumpers were fitted to meet bumper standards.

The MGB was one of the first cars to feature controlled crumple zones designed to protect the driver and passenger in a 30 mph (48 km/h) impact with an immovable barrier (200 ton). [6] [7] Nevertheless, the British AA motoring association has described the car, like many other classic models, as much less safe than modern cars. The issue received public attention following a 2013 case in which a driver in a hired 1963 MGB was killed in a collision with a taxi. [8]

A limited production of 2,000 units of the RV8 was produced by Rover in the 1990s. Despite the similarity in appearance to the roadster, the RV8 had less than 5% parts interchangeability with the original car.

All MGBs (except the V8 version) used the BMC B-Series engine. This engine was essentially an enlarged version of that used in the MGA with displacement being increased from 1,622 to 1,798 cc. The earlier cars used a three-main-bearing crankshaft, 18G-series. In February 1964 positive crank-case breathing was introduced and the engine prefix changed to 18GA, until October 1964, when a five-bearing crankshaft design was introduced, the engine prefix became 18GB. Horsepower was rated at 95 net bhp on both five-main-bearing and earlier three-bearing cars with peak power coming at 5,400 rpm with a 6,000 rpm redline. Torque output on the MGB had a peak of 110 lb⋅ft (150 N⋅m) and fuel consumption was around 25 mpg. [9] US specification cars saw power fall in 1968 with the introduction of emission standards and the use of air or smog pumps. In 1971 UK spec cars still had 95 bhp (71 kW) at 5,500 rpm, with 105 lb⋅ft (142 N⋅m) torque at 2,500 rpm. Engine prefixes became 18V and the SU carburettor needles were changed for reasons of the latest emission regulations, under ECE15. By 1973 it was 94 bhp (70 kW) by 1974 it was 87, with 103 lb⋅ft (140 N⋅m) torque by 1975 it was 85 with 100 lb⋅ft (140 N⋅m). Some California specification cars produced only around 70 hp (52 kW) by the late 1970s. The compression ratio was also reduced from 9:1 to 8:1 on US spec cars in 1972.

All MGBs from 1963 to 1974 used twin 1.5-inch (38 mm) SU carburettors. US spec cars from 1975 used a single Stromberg 1.75-inch (44 mm) carburettor mounted on a combination intake–exhaust manifold. This greatly reduced power as well as created longevity problems as the (adjacent) catalytic converter tended to crack the intake–exhaust manifold. All MGBs used an SU-built electric fuel pump.

All MGBs from 1962 to 1967 used a four-speed manual gearbox with a non-synchromesh, straight-cut first gear. Optional overdrive [10] was available. This gearbox was based on that used in the MGA with some minor upgrades to cope with the additional output of the larger MGB engine. In 1968 the early gearbox was replaced by a full synchromesh unit based on the MGC gearbox. This unit was designed to handle the 150net bhp of the three-litre engine of the MGC and was thus over-engineered when mated with the standard MGB B-Series engine. The same transmission was used in the 3.5-litre V8 version of the MGB-GT-V8. An automatic three-speed transmission was also offered as a factory option, but was unpopular.

Electrically engaged overdrive gearboxes were an available option on all MGBs. The overdrive unit was operational in third and fourth gears (until 1977, when overdrive was only operational in fourth) [11] but the overall ratio in third gear overdrive was roughly the same as fourth gear direct. The overdrive unit was engaged by a toggle switch on the dashboard. The switch was moved to the top of the gearshift knob in 1977. [11] Overdrives were fitted to less than 20% of all MGBs.

There were three different types of overdrive transmissions fitted to the MGB.

  • Laycock Type D OD (note external solenoid)
  • A hole in the bell housing where the starter nose poked through
  • "Shield" shaped access cover
  • 1020 TPM for OD and 1040 TPM for non-OD

The gearbox input shaft, flywheel and engine backing plate were changed with the advent of the five-main-bearing engine in 1965. Therefore, the transmission for a three-main-bearing engine (1962–1964) differed from its later counterpart. [11]

  • Laycock Type LH OD
  • Rectangular shaped access cover
  • Oval clutch fork boot
  • Dipstick (for checking oil)
  • Black label on the OD solenoid cover stamped "22/61972"
  • 1280 TPM for OD and non-OD
  • Speedometer drive gear (on the mainshaft) was blue
  • Speedometer driven gear (on removable drive housing) was white with 21 teeth
  • Laycock Type LH OD
  • Rectangular shaped access cover
  • Square clutch fork boot
  • Side fill plug (no dipstick)
  • Blue label on the OD solenoid cover stamped "22/62005"
  • 1000 TPM for OD and non-OD
  • Speedometer drive gear (on the mainshaft) was red
  • Speedometer driven gear (on removable drive housing) was red with 20 teeth

Overdrive operated in fourth gear only in units made from February 1977 onward. [11]

Early MGBs used the "banjo" type differential carried over from the MGA with the rear axle ratio reduced from the MGA's 4.1 (or 4.3) to 3.9 to 1. (Compensating for the reduction from 15 inch to 14-inch (360 mm) wheels). MGB GTs first began using a tube-type rear axle in 1967. This unit was substantially stronger, being, like the later gearbox, designed for the three-litre MGC. All MGBs used the tube-type axle from 1968.

All MGBs were fitted with 11-inch (280 mm) solid (non-ventilated) disc brakes on the front with drum brakes on the rear. The front brake calipers were manufactured by Lockheed and used two pistons per caliper. The brake system on the MGB GT was the same as the roadster with the exception of slightly larger rear brake cylinders. A single-circuit hydraulic system was used before 1968 when dual-circuit (separate front and rear systems) were installed on all MGBs to comply with US regulations. Servo assistance (power brakes) was not standard until 1975. Many modern and contemporary testers have commented on the very heavy brake pedal pressure needed to stop the non-servo-assisted cars. [ citation needed ]

The MGB initially had an extremely simple electrical system. Dash-mounted toggle switches controlled the lights, ventilation fan, and wipers with only the direction indicators being mounted on a stalk on the steering column. The ignition switch was also mounted on the dash. Like the MGA, the MGB utilized two 6-volt batteries wired in series to give a 12-volt positive earth configuration. The batteries were placed under a scuttle panel behind the seats making access difficult the location gave excellent weight distribution and thus improved handling. The charging system used a Lucas dynamo. Later MGBs had considerable changes to the electrical system including the use of a single 12-volt battery, a change from positive to negative earth, safety-type toggle (rocker) switches, alternator in lieu of dynamo, additional warning lights and buzzers, and most common functions moved to steering column stalks.

From 1972 there were two different Pirelli Cinturato radial tyre sizes factory-fitted to new cars, depending on whether the car was a roadster,(155/80x14) or a GT,(165/80x14).The original tyres for the majority of MG B's were 165HR14 Pirelli Cinturato. [12] With the 1974.5 arrival of the rubber bumper cars the factory-fitted tyre size was simplified to 165/80x14 for all cars, irrespective of whether the car was a roadster or a GT, and also irrespective of the wheel type (wire or RoStyle). The factory built V8s were fitted with alloy wheels and full profile 175HR14 tyres. The "Jubilee" model, made to celebrate the 50th anniversary of the company in 1975 had the alloy wheels from the V8, allegedly because the V8 was not selling and they had a large stock. With a pre-war British racing green colour, tinted glass, gold body stipes and other gold trim 751 Jubilees were made. One was destroyed in an advertising stunt that went wrong. There are thought to be about half of them left as of 2021. [13] The final 1,000 LE models were the last cars to leave the factory with alloy wheels.

The roadster was the first of the MGB range to be produced. The body was a pure two-seater a small rear seat was a rare option at one point. By making better use of space the MGB was able to offer more passenger and luggage accommodation than the earlier MGA while being 3 in (76 mm) shorter overall. The suspension was also softer, giving a smoother ride, and the larger engine gave a slightly higher top speed. The four-speed gearbox was an uprated version of the one used in the MGA with an optional (electrically activated) overdrive transmission. Wheel diameter dropped from 15 to 14 inches (360 mm).

In late 1967, sufficient changes were introduced for the factory to define a Mark II model for the 1968 model year. [16] Changes included synchromesh on all four gears with revised ratios, an optional Borg-Warner 35 automatic gearbox (except in the US), a new rear axle, and an alternator in place of the dynamo with a change to a negative earth system. To accommodate the new gearboxes there were significant changes to the sheet metal in the floorpan, and a new flat-topped transmission tunnel.

To meet US safety regulations for the 1968 model year, the MGB received a plastic and foam rubber covered "safety" dashboard, dubbed the "Abingdon pillow", and dual circuit brakes. Other markets continued with the steel dashboard. Rubery Owen RoStyle wheels were introduced to replace the previous pressed steel versions in 1969 and reclining seats were standardised. [ citation needed ]

1969 also saw three windscreen wipers instead of two to sweep the required percentage of the glass (US market only), high seat backs with head restraints and side marker lamps. The next year saw a new front grille, recessed, in black aluminium. The more traditional-looking polished grille returned in 1973 with a black "honeycomb" insert. In North America, 1970 saw split rear bumpers with the number-plate in between, 1971-1974 returned to the earlier single-piece full-length style chrome bumper. [ citation needed ]

Further changes in 1972 were to the interior with a new fascia.

To meet impact regulations, 1974 US models had the chrome bumper over-riders replaced with oversized rubber ones, nicknamed "Sabrinas" after the British actress Sabrina. In the second half of 1974 the chrome bumpers were replaced altogether. A new, steel-reinforced black rubber bumper at the front incorporated the grille area as well, giving a major restyling to the B's nose, and a matching rear bumper completed the change.

New US headlight height regulations also meant that the headlamps were too low. Rather than redesign the front of the car, British Leyland raised the car's suspension by 1-inch (25 mm). This, in combination with the new, far heavier bumpers, resulted in significantly poorer handling. For the 1975 model year only, the front anti-roll bar was deleted as a cost-saving measure (though still available as an option). The damage done by the British Leyland response to US legislation was partially alleviated by revisions to the suspension geometry in 1977, when a rear anti-roll bar was made standard equipment on all models. US emissions regulations also reduced horsepower.

In March 1979 British Leyland started the production of black painted limited edition MGB roadsters for the US market, meant for a total of 500 examples. Due to a high demand for the limited edition model, production ended with 6,682 examples. The UK received bronze-painted roadsters and a silver GT model limited edition. The production run of homemarket limited edition MGBs was split between 421 roadsters and 579 GTs.

The last MGB roadster produced at Abingdon returned to Abingdon County Hall Museum on 1 December 2011, with the help of British Motor Heritage. [17] It was lifted up 30 feet through a first floor window of the Grade I listed building with inches to spare [18] and now forms part of the collection on display in the main gallery. [19]

Work on a successor for the MGB had been undertaken as early as 1964 with the EX234, but due to the excellent sales of the MGB and Midget, BMC cancelled it in 1966. [20] In 1968 a second proposed replacement was developed, the ADO76, but British Leyland had ceased work on that project by the end of 1970 the ADO76 would ultimately become the rubber-bumper version of the MGB in 1974. [21] When the Abingdon factory finally closed in late 1980, British Leyland did not replace it, with the EX234 prototype finally being sold at auction in 2016.

The decision to discontinue the MGB came about largely due to the poor sales performance of the Triumph TR7, which had largely taken over as BL's contemporary offering in the small sports car market. BL management felt that continued production of the MGB was cannibalising the TR7's sales and this therefore was a justification for taking it off the market. However the TR7 failed to sell and was axed a year later. The MG marque was subsequently used to badge engineer sports versions of the Austin Metro, Austin Maestro and Austin Montego throughout the 1980s, prior to the re-emergence of the MGB in late 1992 as the MG RV8.

Trial in the Desert

DARPA Grand Challenge winner Stanley (L), runner-ups Sandstorm® and H1ghlander (middle). The winning Stanley VW Touareg team was headed by Stanford Artificial Intelligence Laboratory professor Sebastian Thrun. Carnegie-Mellon’s Sandstorm and sister Humvee H1ghlander lagged just behind. All used similar technology, refined from the less successful 2004 event. Credit: Courtesy of Carnegie Mellon University

In 2004, the U.S. Defense Advanced Research Projects Administration (DARPA) challenged dozens of teams then working on autonomous vehicles to compete for a $1 million prize. The hope was that a third of military vehicles would drive themselves by 2015.

Sebastian Thrun, team leader for Stanley, winner of the 2005 Grand Challenge. Thrun lost a friend to an auto accident in his youth, which motivated him to research self-driving. When he led the Stanley team he was Director of the Stanford AI Lab. He later co-founded Google’s self-driving effort and Google [x]

The first year’s crop of entrants failed miserably, traveling barely a few miles before crashing. But the next year an odd flotilla of driverless cars and trucks were crossing huge swathes of California’s Mojave desert with nary a scratch. By 2007 the Urban Challenge had extended those successes to a mock city environment. While European researchers had laid the groundwork in self-driving, the U.S. was now a serious contender. Several factors made the difference: Better software for road-following and collision avoidance, and improved radar and laser sensors. Good mapping also helped. While machines lag behind animals in interpreting their environments, a car that always “knows” what’s around it can focus its interpretive skills on variables that change.


Although we may take bikes as a given, their technological evolution is far from over. Manufacturers are constantly competing to make lighter, more aerodynamic, and stiffer frames for racing, pushing the boundaries of current manufacturing technology to further improve the speed and efficiency of bicycles. Bikes are used around the world for commuting and are currently gaining in popularity across the US and other parts of the world as people seek out greener alternatives to cars, buses, and trains. In addition, the recent rise of electric bicycles has resulted in an entirely new world of bicycling in which bicycles need not be human powered at all.

Off Road Suspension 101: An Inside Look

When it comes to truck suspension, many four wheelers see it only as an instrument to fit the desired tire size they want under their truck. They are concerned only with lift, not function whereas engineers have much more to consider. “Packaging is a big factor,” says Craig Hall of Craig Hall Designs, “We look at the tire size, shocks, suspension travel needed and the working limits of the CV joints, spherical bearings, and other hardware. Once you factor in the limits of the hard parts you are using, the laws of physics will dictate what the final design becomes.”

The specialized off-road racing vehicles that Craig Hall creates may not look like your truck but they use the same basic suspensions designs found on production vehicles. In its most simple role, your suspension needs to hold your truck up and keep your tires planted on the ground. There are several ways to get that done but each has strengths and weaknesses.

You cannot compare factory suspension designs without talking a little about caster and camber. Caster angle is built into the front suspension so the steering is more stable and will return to center. Camber is the angle of the tire to the road – negative camber is when the tire leans in at the top and in contrast, positive camber is when the tire to leans out at the top, seen below.

Old Faithful, The Solid Axle

First let’s look at the solid axle. A solid axle is just that, an axle that runs from one side of the vehicle to the other. The entire axle moves as the suspension cycles. Simple and durable, the leaf spring/solid axle configuration has been used by most manufacturers for decades. It is still coveted by hardcore four wheelers.

The reason this design has survived for so long is because it does double duty as leaf springs suspend the vehicle and locate the axle. Attached solidly to the axle with U-bolts, the leaf springs run parallel to the frame. The springs are mounted to a solid perch on one end and a shackle that pivots on the other end. When the axle hits an obstacle, the leaf spring compresses getting flatter and longer, the shackle allows the spring to move without binding.

According to Fernando Gutierrez of Atlas Spring, “Most coil springs have a linear spring rate. Because of the leaf spring’s multi-leaf design, they have a progressive spring rate. The more they compress, the higher the spring rate rises. By varying their width, length, arch, thickness and number of leaves, they can suspend anything from a Suzuki Samurai to a cement truck. They work best with a shock that has the necessary damping to control the springs in rebound. Leaf springs are large and they need space to work. That’s why you see them used mostly in the rear and/or on larger trucks. Smaller more compact trucks and SUVs sometimes don’t have enough room to run leaf springs, especially in the front.”

Radius Arm Setup

Some solid axle designs use coil springs instead of leaf springs. Coil springs are more compact than leaf springs but they only support the vehicle’s weight they cannot locate the axle like leaf springs do. The suspension members need to locate the axle while also allowing it to move. The radius arm design uses two arms that run parallel to the frame. They mount to a perch on the frame and solidly to the axle housing and allow the axle to pivot up and down. A track bar runs from the frame to the axle perpendicular to the radius arms to keep the axle centered on the frame. Since the radius arms are fixed at the axle end, the caster angle changes when the suspension cycles up and down, shown in the figure above. Radius arm designs have been used by Ford and Dodge among others.

Parallel and Triangulated Four-link

A variation on the radius arm suspension is the parallel four-link, shown in the figure above. Aftermarket manufacturers make kits that retrofit an existing radius arm suspension to a parallel four-link design and use coil springs and a track bar to center the axle. Instead of a radius arm with a fixed mount on the axle, it uses an upper and lower link on each side with pivots on both ends. As the axle cycles up and down, the links allow it to maintain the same relationship with the ground and the caster angle remains constant. Anytime you add a pivot, you add a wear item and the potential for deflection. What the parallel four-link gives up in strength compared to the radius arm, it makes up for in better ride quality and handling.

Another four-link design is the triangulated four-link. The parallel four-link needs a track bar to locate the axle side to side. With a triangulated four-link design, if the links are mounted at great enough angles, a track bar is not needed. When the top links are wider at the frame and narrow at the axle housing, then the lower links are mounted with opposing angles. The greater the angles, the more the links will resist side to side movement.

There is one more link type, solid axle design that is preferred by some of the most extraordinary trucks on the planet: Trophy Trucks. Trophy Trucks travel across the desert at speeds exceeding 130 mph. Running tires up to 42-inches tall, they have solid axles in the rear with trailing arms and a wishbone.

A Trophy Truck’s suspension is designed for maximum suspension travel and most are able to travel as much as 36 to 40-inches. Trophy Trucks are all custom-built from steel tubing they do not have a frame, and the long, boxed construction trailing arms run parallel to the frame. The trailing arms attach low on the chassis in the front and to mounts below the axle housing at the opposite end through either spherical bearings or heim joints on each end. The wishbone is shaped like a “V” and the wide part of the “V” mounts higher to the chassis above the trailing arms whereas the narrow end attaches to the rear end housing with a single bolt.

Not only does it allow the rear end to travel freely up and down but the single pivot on the wishbone lets it articulate freely. Without the coilover shocks and huge, custom built, position sensitive bypass shocks mounted to the trailing arms, it would be very difficult to control the huge fabricated axle assembly and heavy bead lock wheels and tires.

Ford Twin Traction Beam

This Toyota Tundra was retrofitted with an I-beam setup usually found on Fords. Notice the positive camber at full droop.

Ford has an independent suspension design that is part solid axle and part independent suspension – the Ford Twin Traction Beam or TTB. The TTB is similar to a solid axle except the drive axles and housing pivot in the center. It came from Ford with either leaf springs or coils. The two-wheel-drive version is called the twin I-beam. The TTB design works well as designed but has been maligned by many, usually due to modifications done by the end user. Complaints of unusual tire wear and bump steer are typical after installing a lift kit. Many times the culprit is the steering linkage, not the TTB design itself.

We talked to Geoff Falzone of Giant Motorsports about the TTB design. “The biggest knock on the TTB design is how it looks when it cycles,” said Falzone. “It looks strange due to the camber change. Because it pivots in the center, the wheels swing on an arc that causes the camber to change. It may look strange, but TTB is very strong due to the length of the beams. It spreads the stresses out and has a much better shock ratio than A-arms.”

“The passenger side beam needs to be gusseted if you are doing a lot of off-roading,” continued Falzone. “It’s important to maintain the bushings and steering components on a TTB suspension. A lot of complaints about handling come from worn bushings.”

Fully Independent Suspension

Four wheel drive independent rear suspension is not widely used. Manufacturers have dabbled with the design but mostly to improve performance on the pavement, not in the dirt. Production trucks have to transport people, carry cargo, tow trailers, and meet cost constraints so simpler is better to most manufacturers. Rear engine desert racing vehicles use an independent rear design using a single trailing arm on each side. In order to keep everything compact, they run a transaxle mounted directly to the engine transmission. While they are independently suspended, they are specially built for racing and only two wheel drive.

Four wheel drive independent suspension in the front is very common and has been in use for decades because it provides better ride comfort and is much more compact. Struts, coils, and torsion bars are all used to suspend the vehicle on this suspension type depending on application. On smaller trucks, the axles are pushed farther forward there is little room left for leaf springs. The most common independent suspension design up front is unequal length A-arms. Two arms mounted perpendicular to the frame attach to an upright that holds the hub assembly. Both arms pivot at both ends but the top arm is usually shorter than the bottom arm to keep the tire parallel to the ground as it cycles up and down through the range of travel. The A-arm design keeps the caster angle consistent and the camber where it needs to be during the full range of motion.

The compact nature of the design is good for packaging but the downside is that it gets crowded. The drive axle, steering linkage, shock, and spring all fight to occupy the same small space. When A-arm suspension first appeared, it offered a new challenge to aftermarket suspension companies because there were no simple ways to lift the vehicle more than an inch or two. They designed drop brackets that moved the suspension mounting points farther from the frame but they did nothing to improve the strength or performance of the factory design. This prompted several niche manufacturers to build custom long travel suspension systems that use technology developed in off-road racing. Longer and stronger arms, beefy attachment hardware, and state of the art shocks give huge performance gains over the factory set-up. Will all of their complexity, A-arms are considered to be more expensive to get large amounts of travel whereas a TTB setup allows you to get a decent amount of travel for relatively less money.

One such company that took their racing technology to the streets is Brenthel Industries. Their “Baja Kits” suspension systems allow you to bolt on race quality parts to your factory suspension mounts. Brenthel builds kits and they also design and manufacture race vehicles that compete from Baja to Dakar. Their racing experience helps when it comes time to design their Baja Kits.

“The rear straight axle and four-links on our race vehicles are very stout,” said Jordan Brenthel of Brenthel Industries. “The front end takes more hits and has less travel, it is more likely to suffer damage and wears faster than the rear when you are pushing hard. Independent suspension with long travel and four wheel drive gives you a comfortable ride with the ability to absorb the bumps at speed. The traction you need for slow speeds or deep silt and sand is there when you need it. It’s the best of both worlds.”

Brenthel may have his mind made up as to what the best four wheel drive suspension design is but the debate rages on in the Ultra4 racing series. Ultra4 started on a bet when 13 rock crawlers met on a dry lake bed in 2007 to see if they could run all the hammers trails in Johnson Valley in a single day. They did it and from that day on they would be the O.G. 13. Their challenge turned into a full blown race, the King of the Hammers (KOH), and now spawned a national series. King of the Hammers combines the high speeds of desert racing with some of the most challenging rock climbing trails in the country and is considered to be one of the toughest motorsports events on the planet. The first few years, there were many production based vehicles in the field. Competitors are now building innovative tube framed beasts for the race, filled with custom made components. In only seven years, the King of the Hammers race has become a major driver of four by four technology.

King of the Hammers Suspensions

Every year, there is an ongoing debate at KOH as to which suspension design will be superior straight axle or independent. Independent reigns supreme in the open desert whereas the straight axle rules the rocks according to some. Shannon Campbell, a two-time King of the Hammers, prefers the independent design. “Independent doesn’t beat you up,” said Shannon. “At KOH there are so many whoops, (the endless choppy bumps formed in the dirt), the independent suspension is so much better at speed. I’ve owned both types of cars the solid axle is simple and reliable but independent goes just as good in the rocks. When it comes to speed and drivability, independent is better.”

Loren Healy has also been crowned the King of the Hammers two times and both times he was driving a straight axle car. “We won the Hammers race twice with a straight axle car,” said Healy. “I prefer a straight axle in the rocks. You get much more steering angle and you don’t have to beat the car on the rocks. With a straight axle, one tire can lift the entire front end of the car. An independent front will just flex the suspension on one side. You really have to keep the tires on top of the rocks with A-arms. With a solid axle you don’t have to be so precise.” Healy just built an A-arm car and won four straight races with it. “Our new car is very fast but the races we won didn’t have the huge rocks KOH has. We are going to give the A-arm car a shot at KOH this year just to see how it does.”

The debate between the independent suspensions versus the straight axle crowd will probably never be settled. Both designs are proven capable off-road. Independent is more comfortable at speed but with it comes complexity. The solid axle may not ride the best, but the simple durable design shines when things get tough. The TTB falls somewhere in between and does allow the pre runner crowd to get more travel for less money when compared to A-arms.

Let us know what type of suspension you prefer in the comment section below and if you want to see more in-depth suspension related articles, let us know!

Watch the video: Basics of Automotive Leaf Springs and Coil Springs (May 2022).