1967 Harley-Davidson Softail Prototype

Mecum Auction: 1967 Harley-Davidson Softail Prototype


  • 2,400 miles since build
  • 1967 Pan-Shovel Roadworx sub-shock
  • 3 inch stretch chassis
  • Prototype for Harley-Davidson Softail
  • 1 of 36 produced by Roadworx before being bought out by Harley Davidson
  • 1 of 6 produced with 3-inch stretch
  • Harley-Davidson VIN no. on engine block
  • Roadworx build no. on chassis
  • 1967 Shovelhead engine double plug
  • New Ultima 4-speed transmission
  • Le Pera seat
  • S&S carburetor
  • Fat Boy rear brake
  • Big Dog master cylinder
  • Wide Glide front, all new
  • Extra seat and sissy-bar included
  • Extensive documentation including build receipts, Certificate of Authenticity and magazine article
  • Buyer to receive two vintage bike magazines, backing up Roadworx' invention of the Softail frame
  • Receipts from restoration, Roadworx assembly instructions and mail order brochure included

This remarkable 1967 Harley-Davidson is modified by Bill Davis’ Road Worx in the original, prototypical version of what became known as the Softail. It’s one of 36 machines produced with the Sub Shox rear subframe, the second-generation version of the Davis’ softail concept, to make a normal swingarm Harley-Davidson look like it has a rigid frame while retaining a full range of motion for the rear wheel. This motorcycle started life as a 1967 FL with a “Pan-Shovel” (generator Shovelhead) engine.

Bill Davis was an engineer for McDonnel-Douglas in the mid-1970s and also designed and built frames for the family-owned Osborn Racing of St. Louis, Missouri. In the 1960s, Davis, in an inspired conception, applied his skills to designing an aftermarket motorcycle subframe that gave clean lines and good handling to an apparently rigid frame; it was also a direct bolt-on accessory to any post-1935 Harley-Davidson Big Twin rigid frame. It took seven years of trial and error prototypes to get the first design to work. It featured a triangulated swingarm that pivoted at the bottom of the motorcycle frame, with a hydraulic shock at the top of the frame. Davis built 25 of these frames, which used a drum rear brake.

In 1975, Davis redesigned his subframe, moving the pivot point to the center of the subframe, laying the shock beneath the motor for a cleaner aesthetic and better weight distribution, and incorporating a disc brake at the rear. This proved a much better solution, and Davis patented his design. Davis built 11 of these second-generation frames; the first six were built with a 3-inch stretch with reduced fork rake for proper handling. In August 1976, Davis invited Wille G. Davidson to inspect his design, and while he was pleased with the design and the handling of the motorcycle, Davidson informed Davis that the factory was “not yet ready” to purchase his design.

Davis put together a team to produce his frame, marketing them through magazines as the Road Worx Sub-Shock and producing a slick catalog and detailed step-by-step instructions on assembly. Orders began coming in, but only a few were built before internal problems with a partner in the small Road Worx company stopped production. Shortly after that, Harley-Davidson CEO Jeffrey Bleustein apparently asked Davis to Harley-Davidson with one of his kits to prove it was really a bolt-on accessory, which he did as promised. Bleustein negotiated with Davis, coming to a purchase agreement in January 1983 to sell the patent, tooling and Davis’ own personal prototypes to Harley-Davidson. The factory made a few modifications for production, and the first FXST Softail was announced in June 1983.

This 1967 Harley-Davidson FL can be considered the third Softail built, as this second-series Bill Davis rear subframe is the type ultimately adopted by Harley-Davidson. The first of the series, Davis’ personal prototype with Road Worx Serial No. HD STL 0001, is currently sitting in the Harley-Davidson Museum. This machine bears Road Worx Serial No. HD STL 0003. This machine has also been modified with professionally installed twin-plug cylinder heads, an Ultima gearbox, La Pera seat, 18K Colony showbike hardware, a Fat Boy rear disc brake and Big Dog master cylinder, new Wide Glide forks, new shotgun exhaust with black jet coat, new generator and starter, and an S&S carburetor. The speedometer is also new and shows 2,400 miles since the bike was completely refurbished. As a piece of unusual Harley-Davidson history it has few peers, as the factory generally did not purchase engineering improvements from independent engineers. With its flame paint job and blacked-out details, it’s also one awesome motorcycle, showing off Bill Davis’ original Softail concept to terrific effect.





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そこで、いつも遠隔でテクニカルなアドバイスをしていただいている先生、Old Bikerのヒロ川口氏に相談。
「グレード 8 ボルトが求めらるが、原因はショックダンパーがヘタリ出してる。ダンパー強化で、反対側にも追加ショック装着するとボルトへの負荷が軽減される。ソフスペンションのキットのダンパー 1本では直ぐに圧が抜けてフワフワになるのでソフテール純正ダンパーを追加して2本にすると良い。スペースが無ければ細い外径のショックが良い。」とのアドバイスをいただいた。




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