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GMC build a motorhome it had a front wheel drive transaxle used in the Oldsmobile Toronado and Cadillac Eldorado with an Oldsmobile 455 cu. (7.5 liter) V8 from the Toronado, but the later models made use of the 403 cu in. (6.6 liter) V8. Both used the GM-designated Turbohydramatic 425 automatic transmission, with 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. The engine was fueled with regular gasoline stored in two 25-gallon tanks. The GMC was equipped with front disk 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 designed only about 14" above the roadway. The low 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 two-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 motorhomes were built in either 23 feet or 26 feet 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 for the 23' coach and 160 inches for the 26' coach. All GMC motorhomes are 96 inches wide and about 9 feet tall including the usually installed roof air conditioner. Interior head room is 76 inches. Gross vehicle weight rating for the 23' coach was 11,500 pounds and 12,500 pounds for the 26' coach. Most GMC's with factory interiors have a 30-gallon freshwater tank and a 30-gallon 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. GMC's are notable for their large expanse of windows, which redefined the RV industry at the time. By avoiding materials that can rot in the body skin and frame of the motorhome, the GMC's retain a reputation as being the most restorable and rebuildable of vintage motorhomes. Many formerly abandoned GMC's have been successfully brought back to life because of the durable design.
By: Robert Lz Copyright © All Rights Reserved
Taken: November 11, 2007
Uploaded: November 11, 2007
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