For much of the 20th century, General Motors was at the forefront of design innovation in the widest variety of transportation devices. Nowhere was the company's spirit of ingenuity more evident than in the creative development, engineering, and marketing of the 1972 to 1978 GMC MotorHome program.
Although I have never taken a vacation in a recreational vehicle, not even a travel trailer, I have long been fascinated by all forms of what are essentially portable hotel rooms. When it comes to the most inventive recreational vehicles ever built, the leading candidates in my opinion are the revolutionary motorhomes GMC built from 1973 to 1978.
That's right, GMC. Now, I know what you're picturing: a motorhome built on a GMC chassis, not a GMC-designed and manufactured motorhome. But you would be just as wrong as I was when I first came across these classics. The 1973 to 1978 GMC front-wheel-drive motorhomes remain the only such recreational vehicles built in house by a major automotive manufacturer.
General Motors designed the GMC MotorHomes from the ground up at a time when America's car company owned 50 percent of the domestic market. In those heady days, no concept, no matter how outlandish at first glance, was beyond the company's grasp.
Designed to be a halo vehicle for the entire GMC line, the motorhome would leverage the expertise GM teams had accrued in designing and building both trucks and commercial buses. GM's experience with reinforced plastics literally underpinned the construction of the RV's space-age-looking body.
Powered by a modified version of the Oldsmobile Toronado's innovative big-block, front-wheel-drive drivetrain, the GMC MotorHome set standards for recreational vehicle design that remain unsurpassed.
Moreover, almost 35 years after the last unit rolled off the specialized assembly line, these classics of the American road have engendered a cult-like following among classic motorhome aficionados.
I discovered these unique vehicles almost by accident while on a knowledge quest for background information on the Cadillac Eldorado. (The Eldorado is related to the Toronado due to the similarity of their front-wheel-drive drivetrains.)
Unlike most of its contemporaries--boxes built upon a rear-wheel-drive truck chassis supplied by one of the Big Three--the GMC MotorHomes were built on a chassis specially developed for use as a motorhome. The GMC team constructed a totally integrated package that placed all drivetrain components up front, resulting in a flat floor just 14 inches above the road. Combined with a very low step-in height (about the same as a contemporary truck-based body-on-frame SUV), it broke away from all motorhome conventions of the time.
The GMC MotorHomes were powered by a front-to-back-mounted 455-cubic-inch Oldsmobile V8 (downsized to 403 cubic inches for the last two years of production, 1977-1978). The engine was combined with a GM-designed Turbo-Hydramatic 425 automatic transmission placed alongside the engine. The result was an extremely compact layout.
This marvel of packaging efficiency employed a wide chain drive to connect the output of the longitudinally oriented engine to the transmission. The final drive was connected directly to the transmission, and power was fed to the front wheels using half-shafts that ran under the front portion of the engine.
To maintain the flat floor front to rear, the engineers at the GM Tech Center in Warren, Michigan eliminated any sort of traditional rear axle. In its place, they substituted an equally innovative rear suspension: a tandem pair of wheels on each side mounted on bogies, which rode on pins attached to the sides of the low-profile frame. The result was minimal intrusion into the cabin. With the exception of the wheel wells--which are concealed behind cabinets--the rear suspension does not intrude into the living space.
A further innovation was the use of airbags for the suspension system. These gave the GMC MotorHome the benefit of an automatic leveling system that could adjust ride height, as well as level the cabin when parked at a campsite.
Compared to the competition, GMC MotorHomes were exceptionally compact, measuring either 23 feet long on a 140-inch wheelbase or 26 feet long on a 160-inch wheelbase. Yet they were surprisingly spacious on the inside. No matter the length, all GMC MotorHomes measure 96 inches wide (the maximum allowed at the time) and less than 110 inches high (a figure that includes the standard roof-mounted air-conditioning unit).
Inside the cabin, the floor-to-ceiling height measures 76 inches. The vehicles boasted a low center of gravity, which contributed to class-leading driving dynamics of which other motorhomes could only dream.
The GMC MotorHome deviated even more from its competitors in the area of body construction. Instead of using the typical wood frame covered with aluminum, GM engineers employed a rigid welded-aluminum frame mounted on a traditional steel ladder frame using body isolators to save weight. The body itself was designed with weight reduction in mind throughout.
With their expertise in molding the complex panels for the Corvette, GM's designers specified that lower body panels for the GMC MotorHome be constructed from molded fiberglass below the body's waistline. The upper side body and roof panels between the ends are sheet aluminum.
Without the wood frame found in most other recreational vehicles, GMC MotorHomes have very little on them susceptible to rot, which contributes to their unrivaled longevity. The GMC version had more in common with the construction of aircraft than with other RVs against which it competed (think boxy, unaerodynamic Winnebagos).
The design of the GMC MotorHomes provided for unrivaled flexibility when it came to outfitting their interiors. The 23-foot models typically sleep four, while the 26-foot models easily sleep six in comfort. As the brochures from the era illustrate, there is nothing claustrophobic about a GMC MotorHome. With their huge windows, the interiors are bright and airy. Customers had their choice of myriad interior configurations and a seemingly limitless number of trim combinations.
While GMC offered ready-to-drive motorhomes for purchase at GMC dealers, the company also sold a shell--the Transmode--that could be outfitted by outside vendors. This allowed for even more floor-plan and personalization options.
Many owners have lovingly maintained their motorhomes' interiors in period-correct Seventies' style, with plaid upholstery and colorful vinyl. Others have modernized their classics, outfitting them with all the amenities of a 21st-century recreational vehicle. It is not uncommon to find interiors as luxurious as those on a private jet, complete with state-of-the-art galleys, flat-panel televisions, and high-end A/V systems.
Scan the ads on eBay and Craigslist, and you're sure to find running examples of GMC MotorHomes for as little as $5,000. At that price, expect the interiors to require a total renovation. Still, all but the worst basket cases are candidates for restoration.
Well-maintained examples typically start at $15,000 or so, with high-end restorations easily topping $30,000. Bethune Sales is one of the online sites offering a great cross section of GMC MotorHomes for sale.
And yes, for you Bill Murray fans, it was a converted GMC MotorHome that became the EM-50 Urban Assault Vehicle immortalized in the 1981 blockbuster and comedy classic Stripes.
With their big V8 engines, aerodynamic bodies, advanced suspension, and high-tech construction, it should come as no surprise that the GMC MotorHomes set benchmarks for performance and efficiency. In spite of weighing more than 12,000 pounds, they are capable of reaching 100 miles per hour while delivering eight to 10 miles per gallon.
Their drivetrain components were incorporated into countless GM vehicles built in the Sixties, Seventies, and early to mid Eighties, so maintaining a GMC MotorHome is surprisingly easy. Prospective buyers will find strong club support and an established supplier base.
For those of you interested in even more details about the design and engineering innovations in these road-going Holiday Inns, take a look at Bill Bryant's three-part series in the February, March, and April 2004 issues of Family Motor Coaching.
The equally excellent GM Motorhome Enthusiast website (where I located many of the brochures and images seen here) offers compelling reading if you are as intrigued as I am by these technological marvels.
Over its 103-year history, General Motors has been responsible for many landmark vehicles: the V16-powered Cadillacs of the Thirties, the Tri-Five Chevys of the Fifties, the Pontiac GTO, and, of course, the Corvette, America's sports car. GM trucks and tanks helped win the Second World War. The Suburban, marketed by both Chevrolet and GMC, is considered by many to be the grandfather of today's SUV.
And as much as any company in the United States, GM laid the foundation for the middle class. From its assembly line workers to management, the company gave a generation of Americans the ability to buy homes, raise families, and enjoy the fruits of their labor. During the affluent Sixties, Americans hit the road in record numbers, the summer vacation now a staple of suburban life. Recreational vehicles became ingrained in the fabric of post-War America.
The GMC MotorHomes were conceived at a time when GM could marshal the resources necessary to build almost any transportation device its designers imagined. Although priced beyond the means of many (starting at $15,000), this was the RV to aspire to.
Almost four decades after the last one was produced, the 1973 to 1978 GMC MotorHomes remain the standard against which all others are measured. State of the art at introduction, many of its current owners believe that it has yet to be surpassed in terms of ingenuity and versatility --and most would not be seen behind the wheel of any other recreational vehicle.