1973 GMC Motorhome (26-ft model)
|Manufacturer||GM Truck and Coach Division (General Motors)|
|Assembly||Pontiac West Assembly, Pontiac, Michigan|
|Designer||Michael Lathers, GM Design Center|
|Body and chassis|
|Body style||Class A Motor Home|
|Layout||Longitudinal front-engine, front-wheel drive|
455 cu in (7.5 L) Rocket V8|
403 cu in (6.6 L) Oldsmobile V8
|Transmission||3-speed TH-425 automatic|
140 inches (3,600 mm)|
160 inches (4,100 mm)
23 feet (7.0 m)|
26 feet (7.9 m)
The GMC Motorhome was manufactured by the GM Truck & Coach Division for model years 1973-1978 in Pontiac, Michigan, USA — as the only complete motorhome built by a major auto/truck manufacturer and serving as a "halo" vehicle for GMC. The motorhome was conceived not as just a "camper," but as a vehicle for comfortable travel as well. The design was radical for the day with front-wheel drive and a low profile, fully integrated body.
Motorhomes are typically manufactured on drivetrain equipped frames supplied by a chassis manufacturer. GMC built the bodies and in most cases the interiors in-house, and designed the chassis and drivetrain to create the motorhome. Empty shells were supplied to other RV manufacturers for upfitting the interiors and also to specialty manufacturers for a range of custom purposes ranging from mail delivery and mobile training facilities to people movers and ambulances. The GMC Motorhome was built in 23 and 26 ft (7.0 and 7.9 m) lengths.
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Prior to the introduction of the GMC Motorhome, a handful of other manufacturers made use of a similar front-wheel drive configuration and inspired the GMC configuration. These included the Cortez Motor Home from the Clark Equipment Corporation which initially offered a four-speed manual transmission with front-wheel drive, available from 1963 to 1970 until the division was sold to Kent Industries. From 1971 to 1977, a redesigned Cortez-SD was manufactured, initially by Kent and later a group of investors, using the same Oldsmobile 455 and three-speed automatic transmission that the GMC motorhome would adopt in 1973.
Another parallel design was the Revcon motorhome, which starting in 1971 was an all-aluminum body front-wheel drive coach, initially with the same Toronado drivetrain as the later GMC. Beginning in 1978, the Revcon took on a more aerodynamic design similar to the just-canceled GMC Motorhome, which included a slant nose and dual rear axle, while adopting a Chevrolet 454 engine and Turbo-Hydramatic 475 transmission. These were in production through 1990, with one coach built in 1991 using remaining components before the factory closed.
Design and specifications
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Industry rumors had been circulating for some time that GM was going to build a motorhome. On February 7, 1972, it was made official. About this time the new vehicle was known as the TVS-4, Travel Vehicle Streamlined. The motorhome design continued to evolve in the two main areas of styling and chassis. The Design Center was continuing with both the external and interior designs. There were twelve designers working with sketches and 1/8 scale (A-scale) clay models. Three or four of these 1/8 scale clay models were made, each with unique design characteristics, each refining their shapes closer to the final form. Once these models were completed, evaluated and approved, full sized drawings were made using 1/4 inch tape to outline the front, rear and side design. These drawings would guide the designers in the next stage: a full size clay model.
The clay full scale 26-foot (7.9 m) motorhome was created. Once the shape was completed, the clay surface was “polished” with a sponge and cold water and finished with a silver-blue film of DI-NOC, replicating the painted surface of a vehicle. Upon completion of the full scale clay, plaster cast segments were made of it. Dimensional drawings were made of this final design for tooling and early fiberglass prototype parts for the first prototype bodies.
The motorhome had a front-wheel-drive transaxle, which GM called Unified Powerplant Package, originally used in the Oldsmobile Toronado and Cadillac Eldorado with an Oldsmobile 455 cu in (7.5 l) V8 from the Toronado, but the later models made use of the 403 cu in (6.6 l) V8. Both used the GM-designated Turbo-Hydramatic 425 automatic transmission, with a wide roller 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. The engine was fueled with regular gasoline stored in two 25-US-gallon (95 l) tanks.
The GMC was equipped with front disc brakes and drums on all four rear wheels. The front-drive configuration eliminated the driveshaft and rear differential and solid axle found on most front-engined motorhomes. As a result, the floor could be built with about 14 inches (36 cm) clearance above the roadway. The floor was too low for a rear cross axle, and GM designed the rear suspension as a tandem pair of wheels, mounted on bogies which rode on pins attached to the sides of the low-profile frame. With the exception of the wheel wells, the rear suspension does not intrude into the living space. The rear bogies are suspended using a double-ended convoluted air bag that is pressurized by an automatic leveling system to maintain the designed ride height. The leveling system can also be manually controlled to level the coach at a campsite. The overall chassis design, from the use of an existing GM E platform powertrain and a modified rear suspension has been considered an early ancestor of the crossover.
The motorhomes were built in either 23-foot (7.0 m) or 26-foot (7.9 m) length, with about 90% of the total production being the latter. The wheelbase from the front wheels to the centerline of the rear tandem pairs is 140 inches (360 cm) for the 23-foot (7.0 m) coach and 160 inches (410 cm) for the 26-foot (7.9 m) coach. All GMC Motorhomes are 96 inches (240 cm) wide and about 9 feet (2.7 m) tall including the usually-installed roof air conditioner. Interior head room is 76 inches (190 cm).
Gross vehicle weight rating for the 23-foot (7.0 m) coach was 10,500 pounds (4,800 kg) and 12,500 pounds (5,700 kg) for the 26-foot (7.9 m) coach. Most GMCs with factory interiors have a 30 US gallons (110 l) freshwater tank and a 30 US gallons (110 l) holding tank.
Body construction consisted of a rigid frame made of welded aluminum extrusions. The body frame was mounted on the chassis steel ladder frame using body isolators. The floor was marine plywood, except where it sloped up at the extremities, where they were plate aluminum. The body panels are fiber reinforced plastic (fiberglass) below the waistline frame extrusion and at the ends. The upper side body and roof panels between the ends are sheet aluminum. GMCs are notable for their large expanse of windows, which redefined the RV industry at the time. They often had luxury features common on upper models of GM brands, such as cruise control, air conditioning, AM/FM/8-track sound systems, an aluminum/fiberglass body, as well as air suspension.
Rear lower compartments provide space for generators and propane tanks. GMCs were optionally supplied with generators from Onan in 4,000 watts and 6,000 watts, many of which are still in service.
A total of 12,921 GMC Motorhomes were produced from model years 1973 to 1978. The interior of the motor home was constructed at the Gemini Corporation plant in Mt. Clemens, Michigan. Peter R. Fink, owner of Travco motor homes, was the CEO of Gemini. The Gemini operation featured a progressive team concept with teams of workers constructing rooms of the motor homes in full, rather than performing repetitive tasks on an assembly line. Beginning operation in 1972, the plant featured state-of-the-art equipment including one of the first programmable routers. Gemini closed a few years after General Motors discontinued production of its motor homes. Over 7,000 are currently listed in an international registry. Estimates suggest that at least 8,000 to 9,000 of the original production are still in running condition.
A press release datelined Pontiac, November 11, 1977 read as follows: “GMC Truck & Coach Division of General Motors plans to discontinue producing luxury MotorHomes and similar TransMode multi-purpose vehicles and convert those plant facilities to expand truck operations, a GM vice president said today. Robert W. Truxell, general manager of GMC Truck & Coach said, “As a result of this action, GMC will be able to utilize production facilities more effectively for servicing growing truck demands.”
The GMC Motorhome has made many theatrical appearances, such as animation series, movies, music video, and television. Along with influencing the toy industry with Mattel produced over 100 different models of GMC Motorhome Hot Wheels and the Barbie Star Traveler Motorhome.
A 1973 GMC Motorhome appeared in the Ben 10 franchise.
In the 1996 movie Twister, the GMC Motorhome was used as the mobile support weather station by "the bad guys team".
A GMC Motorhome appeared in The Six Million Dollar Man Episode The Pal-Mir Escort
A 1973 GMC Motorhome was used as the exterior of the Aquabats' Battletram.
A GMC Motorhome, Birchaven model, was used in the Shooter Jennings music video featuring George Jones in the 4th of July in 2005.
A GMC Motorhome was featured on the reality TV show "Ozzy and Jack's World Detour". The GMC was the choice of Ozzy Osbourne because of his fond memories of touring in one during the 1970s.
- http://www.bdub.net/publications/sob-fwd/index.html Bdub's Place: Other Toronado Powered Front Wheel Drive Motorhomes
- "Archived copy". Archived from the original on 2010-09-06. Retrieved 2010-10-10.
- http://policeinterceptor.com/Revcon.htm PoliceInterceptor.com: Support Page for wide-body 1987-1991 Revcon RV's
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