Table of Contents
A Brief History of the GMC Motorhome
Genesis of a Design
In the heady days after the United States landed a man on the moon, General Motor engineers set out to design the ultimate traveling machine. Drawing on the excitement of the times, this vehicle had to exemplify the cutting edge of vehicle design and construction. This was not to be just another recreational vehicle. The common design of the times for RV's was a boxy, ungainly, top-heavy vehicle on a truck chassis. The GM vehicle was to be innovative in every way. Design work began in 1970, with release planned for the 1973 model year.
The design would draw heavily on General Motors expertise in several areas. First, it was to be front wheel drive. A still rare concept in car design, much less motorhomes. The drive train and front suspension would be the same design that had been used successfully in the Oldsmobile Toronado since 1966; the 455 cubic inch Oldsmobile engine mated to a Turbohydramatic 425 transmission with torsion bar suspension. The rear suspension would draw on GM's leadership in bus design, using dual swing arms(one leading and one trailing) with a single air spring on each side. Automatic controls would be integrated into the suspension to allow the vehicle to compensate for changes in loading and maintaining a level driving condition at all times. The chassis was to be a steel ladder design. The body framing was to be aluminum and the body exterior was to be a combination of heavy gauge aluminum and molded glass fiber reinforced plastic as had been used in the Chevrolet Corvette.
The use of front wheel drive and the independent swing arm rear suspension brought many advantages to this design. The lack of drive shafts and axles passing under the coach allowed a very low floor height compared to other motorhomes. The low floor height also allowed a low overall height and low center of gravity for the coach. This gave the vehicle almost car-like driving qualities.
The emphasis for the design was to be on the traveling experience, not extended “in-the-woods” camping. This resulted in the exterior of the vehicle being dominated by large expanses of glass. Visibility from the driver's seat is panoramic to say the least. The vehicle was to be manufactured in 23 foot and 26 foot models; fairly short for a motorhome. There were no permanent sleeping areas(at least in the original design). All beds were converted from seating areas when needed. Since the floor plan is fairly compact, care was taken in the design of the beds so they did not encroach on aisle space when opened.
To allow hot water to be available while traveling, marine water heaters were used which incorporated engine coolant loops(this can present a scalding hazard as coolant temperatures generally exceed 200 deg. F). Power for the refrigerator was 12 volts DC and the “house” battery(in the original design)was a standard automobile wet cell; adequate only for overnight use without recharging.
After rumors circulated throughout the auto and recreational vehicle industries for nearly two years, the prototype was displayed in May, 1972 at the Transpro '72 trade show in Washington, D.C. Production vehicles debuted in the 1973 model year to general acclaim from the recreational vehicle community. Two models were offered, Model 230(23 feet) and Model 260(26 feet), in two variations Motorhome(provided with GM finished interior) and Transmode(bare coaches sold to RV manufacturers such as Avion and Coachman who provided their own interior).
Although the design was refined along the way, the basic vehicle was never altered. Body panels from a 1973 will fit a 1978. The most notable change came in 1977, when Oldsmobile dropped the 455 cubic inch engine for the 403. By then, the oil embargoes and energy crises of the 70's had taken their toll. “Gas guzzler” vehicles like motorhomes fell out of favor and the entire RV industry fell on hard times. The motorhome was never a high volume vehicle and was rumored never to have been profitable for the automotive giant. General Motors decided that the production facilities would be better utilized in the production of light trucks - estimating they could produce 100 light trucks for every motorhome manufactured. The formal announcement came in November of 1977 and production was discontinued in the 1978 model year after manufacturing around 13,000 total units.
A Classic Endures
Almost immediately, this timeless design attracted a fanatical following. Regional and national owners' organizations sprang up to support the vehicle. Owners wanted to modify their vehicles to make them more amenable to long term camping, and to overcome some of the “compromises” made by GM's purchasing department in their efforts to reduce costs. These club publications were often the only source of information available. As interest in the coaches continued to grow, a cottage industry sprang up around them. Small manufacturers and garages began to specialize in providing products and services for the vehicles.
The major turning point came in 1992, as General Motors prepared to scrap all tooling and remaining parts inventory. Cinnabar Engineering purchased all the motorhome property from GM and negotiated a license to provide OEM parts for the vehicles. This assured availability of quality parts for the foreseeable future. Also in 1992, GMC Motorhome Marketplace, a monthly magazine which has achieved international distribution, was introduced providing a major source of information and advertising, both commercial and classified, for the GMC motorhome owner. In 1994, Cinnabar began publishing their own quarterly newsletter, GMC Motorhome News, which details proper service, modifications and parts availability.
As testimony to the enduring nature of the design, it is estimated that, of the 13,000 units manufactured, it's estimated that 8,000 to 9,000 are still in current registration.
Model 260(26 feet long)
Model 230(23 feet long)
VIN Decoding Example TZE167V102359
T Manufactured by General Motors
Z 3 Axle Motorhome
E Gasoline Engine
1 Interior Code
“1” - GM Interior from 1975 to 1978
“0” - GM Interior from 1973 to 1974
“2” - Twin Bed Interior from 1976 to 1977
“3” - Transmode(sold without interior or windows)
“6” - Model 260(26 feet long)
“3” - Model 230(23 feet long)
7 Model Year(1977)
V Manufacturing Plant Code
“V” - Pontiac, Michigan
1 First Digit of Production Series Number
All production started with “1”
0 Since total production was less than 13,000, all GMC Motorhomes had a zero in this position
2359 Production sequence number
GMC had some notable interior designs in 1975. This was the only year that Avion Coach Travel Trailer Division designed a custom interior for the GMC coach.
Service Parts Identification Label
If the motorhome was furnished with a GMC interior, this label in the glovebox identifies the interior finish model.
- 641 Kingsley
- 681 Glenbrook
- 683 Edgemont
- 685 Coca Cola
- 690 Sequoia
- 692 Painted Desert
- 693 Glacier
- 695Canyon Lands
- 696 Eleganza I
- 698 Palm Beach
It’s even had a movie career, starring in the 1981 Bill Murray comedy Stripes. But for those of you who grew up in the 70s, the GMC will always be known as Captain America’s van.
That’s pretty remarkable for an RV that only had a six-year production run. But there are many, many remarkable things about the GMC. For starters, it was the first RV created and built by an automaker—and to this day, no other automaker has taken that risk.
GM called the project TVS-4 (‘Travel Vehicle Streamlined, model 4’). For maximum grunt, it dropped in a mighty 455ci V8—the engine that powered the 1966 Toronado. A claimed 260 horses were fed through a three-speed gearbox to the front wheels; with no driveshaft running to the back axle, this gave the living area an extra-low floor and lots of headroom.
The GMC looked sharp from the start, sitting low on its haunches. But the front wheel drive gave traction problems on uphill grades, especially in heavy rain or snow. Handling was otherwise decent, helped by a low center of gravity and an air spring setup for the four wheels at the back.
You got the choice of a six-berth 26-foot or a (relatively rare) four-berth 23-foot. The sleek styling gave an amazingly low drag coefficient of 0.39. And the interior was funky even by 70s standards, designed with the help of House and Garden magazine. The wraparound glass looked cool, but in hot weather the large windows put a huge strain on the roof-mounted air conditioner.
At launch, the GMC cost between $12,000 and $16,000. And what a launch it was: the stock prices of all the other major RV manufacturers fell the very next day. Their vehicles suddenly looked very old. As the GMC sales brochure said, you could now buy a “motorhome that doesn’t look like a box or ride like a truck.”
GM originally pitched its motorhome as a ‘multi-purpose vehicle’ for extended living. That was mostly a marketing fantasy, but in 1975 GM did launch an unfurnished Transmode model. Soon, GMCs were being turned into everything from mobile recording studios to laboratories. The Transmode shells were farmed to conventional coachbuilders such as Coachmen, and even Coca-Cola got into the game, offering custom ‘Gadabout’ models as prizes.
And then, suddenly, the wheels came off the bus. The fuel crisis played a part: the GMC’s 8 to 10 mpg thirst was actually pretty good for a Class A with a big V8, but the running costs became too much for the American middle classes.
In 1977 GM shrank the engine to 403 cubes, but the sticker price had already soared to $38,000. There was no place for the world’s coolest RV any more: in 1978, the production line in Pontiac, Michigan was shut down.
12,921 GMCs were made in all, and many are still on the road today. Winnebago released a thinly-veiled copy in the late 80s called the Spectrum 2000, and small numbers of other GMC replicas have been produced by companies such as Silver Motor Coach.
Today, thirty years on, the originals are relatively easy to keep on the road. Rebuilt engines are available for $3,000 or thereabouts, and the bodies are made from long-lasting aluminum and fiberglass.
Some owners restore their GMCs to showroom condition, while others update the interiors in superyacht or Airstream CCD style. The only real bugbear is the underlying frame—which could cost up to $10,000 to fix if decayed. But a thriving restoration industry makes it easy to keep the mechanicals in good running order, led by specialists such as Cooperative Motor Works.
GM itself briefly raised hopes for a Mk II Motorhome with the award-winning GMC Pad design concept in 2005. But nothing more has been heard of this. The future of modern RV design probably lies more in the direction of VW’s acclaimed 2001 Microbus Concept.
There are plenty of GMC links to stoke your appetite, from Flickr sets to extensive histories. The best GMC fansite of all is probably bdub, with its archive of GMC brochure eyecandy and a thorough GMC FAQ for newbies. If you’re hankering after a GMC for yourself, keep an eye on eBay or the big RV classifieds such as rvt.com.
Just remember to set aside $20,000 on top of the purchase price, and then you can create a personalized RV that looks like it’s just rolled off the set of The Jetsons. A much better—and cheaper—proposition than a 40-foot white box with cheesy graphics.
1976 Edgemont, significantly up-graded. Fin & Mary Beven, South Pasadena, CA FinBeven@MSN.com
Richard & Susan Waters and their Palm Beach GMC: