Story Of A Classic: The GMC Motor home Part 1/3

Story Of A Classic: The GMC Motor home Part 1/3

Produced by General Motors from 1973 through 1978, the innovative GMC Motorhome gained a following that is still as strong — if not stronger — today. This three-part series explores the fascinating history of a motorhome still considered by many to have been far ahead of its time.
Following World War II and a lapse of auto production of nearly four years, former GIs and the general public longed for new cars.
Once the pent-up postwar demand was satisfied, auto companies started offering innovative, attractive new designs in an effort to capture a greater market share. At auto shows and Motoramas we saw Thunderbirds and Edsels, Chrysler 300s, Corvettes, GTOs, and Eldorados. New V-8 engines were everywhere; small blocks, big blocks, Hemis; horsepower and cubic inches ruled. New styles were longer, lower, wider, with chrome everywhere and tail fins that soared.
Then came the energy crunch in October 1973, and it all changed. The automotive talk turned to cost and availability of fuel, more efficient cars with new four-cylinder and V-6 engines, and downsizing.

The “pie wagon” or “chicken coop” was used for initial demonstration of the hardware for the rear tandem suspension. The goal was improved ride and handling over a truck-type suspension
Cars became smaller, lighter, less powerful, and with increased fuel economy standards mandated by the federal government.
Automobile companies are always searching for ways to gain more sales, to build a greater market share, and to keep their assembly lines flowing.
New ideas are constantly evaluated, but few see the light of day.
Occasionally, however, a niche is found and a new market is developed.
Truck chassis were successfully marketed to the RV industry in the 1970s by the Big Three.
In 1971 Dodge sold 28,000 chassis to 50 different coach builders. Each RV manufacturer was building its version of what it thought a motorhome should be. There were lots of choices for the motorhome buyer, nearly all of them on a truck chassis. What if someone offered an attractive, advanced design on a custom chassis, unique and specifically made for just that purpose?
One of those niches GM was looking at in 1969-1970 involved ideas for a multipurpose vehicle — a vehicle that could be adapted for use not only as a motorhome, but as an ambulance, a small transit bus, an airport shuttle, a mobile medical clinic, or a display or service van. Evaluations began at the GM Tech Center in Warren, Michigan. Competing motorhome specifications were scrutinized, and floor plans were evaluated. Initially, it was decided to go with 20-foot and 24-foot
motorhome designs.
John Locklin was the GMC employee responsible for motorhome body engineering.
He retired in 1977 and was presented a 1/6-scale model of a GMC motorhome as a gift
Relying heavily on interior designs by GM’s Frigidaire Division, drawings of the numerous floor plans under evaluation lined the Tech Center’s walls.
A full-scale plywood (fiberboard) seating buck was built in the Tech Center’s basement to evaluate the different interior designs. Seating bucks are used to define a vehicle’s requirements for both internal and external packaging. Styling must not violate these requirements if their designs are to remain true for the final production version.
The first chassis built to demonstrate the unique vehicle design was assembled with the now familiar tandem-rear wheel assembly incorporating leading-trailing cast nodular iron arms at the rear, supported with a hydro-air spring from the Saginaw Division of GM.
The power steering pump was used for hydraulic pressure for this suspension system. The engine and drivetrain used the Oldsmobile Toronado front-wheeldrive unit with its 455-cubic-inch engine, 425 Hydra-Matic transmission, and 3.07:1 differential gear ratio from the Toronado trailer-towing option.
The design of this “development mule” allowed for a low-profile chassis with its attendant handling and ride improvements.
The front section of the frame made use of the Toronado design and bolted up to the center Cchannel side rails.
The rear frame extension was unique to the motorhome and was “kicked up” to allow for an adequate departure angle.
A modified van body built by the Union City Body Company, of Union City, Indiana, was mounted on the frame. The chassis had been designed with only 4 inches of ground clearance.
Called the “pie wagon” or “chicken coop” by those working on the project, this development mule was outfitted with windows and bus seats, and sand bags were strategically placed inside to represent the weight of an equipped motorhome. Since spy photographers often took pictures of test vehicles driving around the GM Proving
Grounds, full fender skirts covered the wheels to hide the vehicle’s unique suspension.
The major purpose of this vehicle was to demonstrate to GM management its superior handling and ride in comparison to the truck chassis normally used for motorhomes. It is reported that GM management was favorably impressed and approved further development of the project.
Initially, Chevrolet wanted the motorhome project, but the GM corporate guidelines defined vehicles below 10,500 pounds gross vehicle weight rating (GVWR) as Chevrolet responsibilities and vehicles above that weight as GMC responsibilities.

The project, therefore, went to GMC. This decision, however, did not stop the interdivisional rivalry, which continued throughout the motorhome’s production years.
Chevrolet was a major supplier of truck chassis for the RV industry and considered the GMC Motorhome another competitor.
Chevrolet management made sure that the motorhome carried all of its cost burdens and received no special corporate advantages.
Early in these developmental stages, GMC Engineering was defining just what this multipurpose vehicle should be.

The GMC styling idea was along the lines of the Sportscoach motorhome of the period, with styled front and rear fiber-glass caps, but with straight sidewalls.
This type of design allowed for a reasonably attractive appearance, though ordinary, while minimizing tooling and manufacturing costs.
The GM Design Center had been at work for about two years at this point on various multipurpose vehicle designs. Not surprisingly, those designs looked much different from what GMC had in mind.
There were three-wheeled designs that followed the arc of the sun while parked; panels that extended to add more living space; and scale models of attractive and futuristic designs, as well as numerous sketches and drawings that were well far out

The use of the Oldsmobile Toronado front-wheel-drive unit should not have been a surprise. Four other motorhome manufacturers were utilizing that same system during this time period:
Revcon, Cortez, Travoy, and Tiara. The Revcon was the most successful of the group. Cortez had evolved from the Clark. Travoy was a Riverside, California, company. And the Tiara evolved from the Ultra Van, which had originally used the Corvair engine.
The individuals responsible for the development of the GMC Motorhome were members of a group of bright young professionals. Martin J. Caserio, General Motors vice president and GMC Truck and Coach general manager, envisioned a “Chevrolet” of motorhomes — that is, reasonably priced with a view toward large-volume sales. Caserio’s replacement in 1973, Alex C. Mair, wanted a vehicle more like the “Cadillac” of motorhomes, more upscale than the early models.
A 1/6-scale model of a GMC motorhome
A bright, young, enthusiastic engineer, Kurt Stubenvoll, was in charge of product development for the motorhome. Ralph Merkle headed up chassis development and was responsible for everything from “the frame to the pavement.” Known as “the idea man,” Merkle had a number of patents to prove it. John Locklin came to GM with an aeronautical degree and had responsibility for the motorhome body engineering (he brought new assembly methods and ideas to the auto industry). Michael Lathers from the Design Center was in charge of the motorhome styling (it was to become obvious to all the fine job he did).
Many other talented engineers contributed to what was to become a classic as well.
On February 7, 1972, GM made official what had been rumored in the industry for some time.
The national press reported that GM was to “play a role in the motorhome market.” By this time, the motorhome’s lengths had been identified as 23 and 26 feet.
The increase in length was the result of additional interior content that designers and salespeople felt was necessary for a well-equipped motorhome. GM Sales had identified the need for the 23- foot motorhome as a price leader. Prices were reported to be between $12,000 and $16,000. Major motorhome competitors claimed they were not worried; still, their stock prices fell several points the next day. Smaller motorhome companies indicated immediate concern about the erosion of their market share with giant GM entering this field.
About this time the new vehicle was known as the TVS-4 (Travel Vehicle Streamlined model 4).
Part of the reason this vehicle is so different from other motorhomes of the era is that it was not conceived as just a “camper,” but as a vehicle for comfortable travel as well. Slogans used later in GMC Motorhome advertisements demonstrated this; for example: “It doesn’t ride like a truck, it doesn’t look like a box.” “Our goal was to make getting there as much fun as being there.” “It’s as easy to live with on the road as it is standing still.” “The show place that goes places.” All of these slogans placed great emphasis on the traveling aspects of motorhoming and not just how a motorhome functioned while parked at the campsite.

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