Hugo Becker of BMWBLOG breaks down the history of front-wheel-drive vehicles in the face of a wrong-wheel-drive Bavarian future. — Ed.
In the beginning was the Cugnot artillery tractor. More than one version of the three-wheeled, front-wheel-drive steamer came off the drawing boards in the second half of the eighteenth century. The apocryphal story tells that it plowed off the outside of a corner and into a wall. And thus driven front wheels and understeer were forever linked.
The United States Enters The Fray
Fast forward to the opening years of the twentieth century and a cantankerous designer-inventor by the name of John Walter Christie. He created a series of transverse-engined front-wheel-drive monsters that were raced at fairgrounds across the United States. They were technological dead ends, and while seven were built, none are known to have survived.
In the 1920s, a Kansas City businessman named Ben F. Gregory built around ten front-wheel-drive cars immediately after World War I. These cars had longitudinally mounted engines with a transmission in the nose connected to a front differential. Gregory employed a novel solution to allow power and steering to take place on the same axle, adopting a de Dion tube for the front end of his vehicles.
Around the same time, motorsport visionary Harry Miller was approached by board-track hero Jimmy Murphy and his mechanic Riley Brett and asked to build a front-wheel-drive board-track "killer". Miller suggested a transverse engine layout, but Murphy and Brett wanted a longitudinal layout in order to minimize the car's frontal area. Miller did that, and the race car that resulted cleaned up its oval-track competition. He used Ben Gregory's de Dion front suspension in the process. Once tweaked and cleaned up a little by C. W. van Ranst, his design formed the basis of the Cord L29.
What's interesting is that Miller and Gregory worked with Christie during World War I, and that Riley Brett had experience building cars in Kansas City at the end of war. Unfortunately, beyond those superficial connections, no real ties have been proven to exist between those men.
Up to this point, front-wheel-drive had been hampered by the lack of a solution to the odd pulsating motion that universal joints are subject to when deflected at large angles. This normally isn't a problem on unsteered wheels (or, for that matter, on a rear-wheel-drive driveshaft) as the vertical motion of suspension travel is generally less than that of the horizontal angles necessary for steering.
Effect of angular displacement on universal joint. From Wikipedia.
Back to France
All roads lead to France at this juncture, even though constant-velocity (CV) joints were beginning to be developed elsewhere. A firm known as Tracta was founded to build cars that demonstrated a new, easily manufactured CV joint. It was developed by Jean-Albert Gregorie (odd there's another ‘Gregory' in the mix). This joint was picked up by the German firm NAG and used in cars like the Adler Trumpf. DKW also took interest in the joint and applied it to their two-stroke, transverse-engine "kleinwagen" car. Other CV joints, built by companies like Rzeppa (Ford) and Weiss (Bendix), were available at the same time, but Germany and France were the innovators, and the Citroen Traction Avant was seen as something of a breakthrough.
Across the Channel
In the mid 1950s, automotive designer Alex Issigonis found himself back at Morris, then part of the British Motor Corporation (BMC). His brief was to lay out three new cars, and work was well underway on the first two when the Suez crisis intervened. As a result of the subsequent charge towards small cars, Issignois was approached by BMC's chairman, Leonard Lord, and asked to develop a "proper" small car unlike the "bloody bubble cars". The assignment dovetailed neatly with Issigonis's minimalist thinking — he had wanted to do another small car after his well-received penning of the Morris Minor.
The thinking for third proposal was to maximize passenger space. Issigonis started drawing and calculating space on one of his ubiquitous sketch pads. The idea for the original Mini was to stuff five people and their gear into 10 feet of car along with an engine, transmission, differential, wheel wells, suspension, and all the other bits needed to make the car roadworthy. This constraint of the car's length led to the two-box design that went against prevailing styling norms.
Issigonis had previously experimented with transverse front-wheel drive on a modified Morris Minor, but up to that point, no one had attempted to mass-produce such a vehicle. He utilized a Hardy-Spicer Birfield joint (a license-built Rzeppa), previously used in submarines, to send power to the front wheels. Another issue was the potential intrusion of the wheel wells on passenger space. The solution to this was sourcing a ten-inch wheel and leaning on Dunlop to build an appropriate tire.
The suspension had to accommodate the space restrictions and the potential for the payload to equal the unladen weight of the car. Coil or leaf springs wouldn't work, and the hoped-for Hydrolastic suspension wasn't yet far enough along for a production vehicle. Instead, the initial production vehicles utilized specially developed rubber-cone springs and shock absorbers. (Hydrolastic suspension was incorporated into the car later in production.)
The Mini, which was initially targeted at adults, took a while to become hip. It took the children of those adults to turn it into a hit. And the Mini became the future.
The Road To Ubiquity
The Mini started the trend towards front-wheel-drive ubiquity, but the Fiat 128 added momentum. While Audi and GM (Toronado and Eldorado) still used a longitudinal engine placement, more and more manufacturers migrated to transverse layouts. This was to the detriment of long-standing rear-engine, rear-wheel drive vehicles like the Fiat 500/600/850, the Renault 4CV, the Chevy Corvair, and Volkswagen's entire lineup.
In time, all major entry and mid-market manufacturers would come to rely on front-wheel drive for the bulk of their offerings. Mercedes-Benz and BMW remained the lone holdouts — and while Audi and Subaru offer all-wheel-drive, those offerings are derivatives of front-wheel-drive antecedents.
What Will BMW Do?
BMW has announced that it is planning to build a subcompact (B-class) BMW-badged front-wheel-drive car in addition to its planned potential Project i models. Why would the Bavarians do this? The logical explanation is that emissions and fuel economy requirements in world markets require a lightweight anchor for more extravagant offerings (X5 M, 760Li, etc). There may be engineering reasons for choosing FWD over anything else, but history shows that rear-engined, rear-wheel-drive cars often die when their parent companies make the move toward front-wheel drive.
While this new front-wheel-drive BMW will be available in Europe, it's uncertain whether or not BMW of North America will want it. After all, it represents the potential dilution of the company's brand image in the vital North American market. And historically, Americans have rejected premium small cars. (There are a couple of exceptions and cars like potential ‘Project i' vehicles may have an impact here.) That said, 35-mpg CAFE targets are looming, and we're seeing BMW's migration to smaller, high-tech, turbocharged motors as a result. The question for BMW of America is whether or not it can make its CAFE target without an entry-level front-wheel-drive car. I believe that they'll do everything in their power to meet the CAFE goal without importing a premium front-wheel-drive model.
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