1970 Ford Mustang Boss 302 - Thoroughbred Restoration
Dan Koerselman's Thoroughbred Restoration Is Basically A New Boss 302
Assembling a garage full of high-dollar old parts isn't what makes this level of restoration so difficult. There are many dabs of paint, stamps, chalk marks, and tags that make no sense to an observer at a car show, but a judge looks for them and understands them as significant. For example, Dan's Boss was built in Ford's Metuchen, New Jersey, assembly plant, which means its markings, undercoating, and paint overspray vary from the Boss 302s produced at Dearborn. One well-documented and easy-to-spot difference is that Metuchen cars had the bottoms of their trunk lids painted body color; Dearborn-built Bosses have black paint on the underside of the decklid to match the Boss treatment on top.
"There's a lot of homework with any restoration," Jim says, "and the best way to lay the foundation is to take notes and pictures of every piece you remove during disassembly. All those dots and marks meant something as the car went down the assembly line, and they must be returned if the restoration is to be considered accurate."
Jim is a stickler for assembly line accuracy. For example, on this Boss, he found a small hole in one of the rear framerails that had clearly been created by accident during Ford's unibody welding process. He insisted on retaining the partially hidden blemish to maintain the car's history.
Running changes and fixes on the assembly line account for some oddities in the restoration process, especially with the specialized models.
"Ford got a lot of complaints about the lightweight plastic rear wings on the '69 cars," Jim says. "Sunlight caused them to warp and sag, so stiffer, heavier fiberglass was used for '70. Most of the trunk lid springs were too weak to support the new wing, so assembly line workers had to open and close the trunk three times in order to test the strength. If the lid stayed open on its own, the car moved down the line to the next station; if the lid closed, the worker would drill a hole in the pot-metal end cap on the passenger side and install a prop rod.
"There's no documentation to say whether a specific car got the prop rod or not, so knowing whether or not an earlier owner added or deleted one is important for authenticity. Dan's car came with the rod."
Billy Jay, a professional pinstriper and letterer by trade, worked with Jim during final assembly. He helped install the interior and align the sheetmetal, and he reproduced the dozens of factory markings throughout.
People sometimes confuse Thoroughbred and Concours classes, but there's a world of difference that can only be appreciated by the hardcore enthusiast. Thoroughbreds are built from irreplaceable N.O.S. parts that will never be used for their intended purposes. When a 30-year-old carburetor goes from its dusty old blue-and-white box to the top of an intake manifold, there is minimal chance a drop of gasoline will ever wet its venturis. The only fluids a Thoroughbred enjoys are those that prevent internal rust on moving parts. Concours cars, on the other hand, are restored to and judged by high standards, but they're allowed to have any number of reproduction parts, as long as they meet certain criteria. They also can be fired up and driven, though usually from a trailer to a parking spot at a show.
One factor that makes Thorough-breds such high-maintenance artifacts is that their metal parts must have only as much protection from rust as the factory originally provided, whereas Concours owners are allowed to use specific coatings and clear paints to prevent short-term oxidation.
"I've only seen about 10 to 12 Thoroughbred Boss 302s on the show circuit," Jim says. "There are about as many Boss 429s in that class as well."