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Old 02-24-2016, 12:07 PM   #2
Mitch G.
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Join Date: Apr 2009
Location: Ponte Vedra Beach, FL
Age: 60
Posts: 1,106

Default Re: progression of sprint cars

Jake, glad to have you aboard this site, lots of great members, and stuff. Here's a quick history, open to debate among old guys like me. Sprint cars more or less came about in the 1920's, Harry Miller was America's first race car producer, he started a company that built race cars not of stock origin. In the early days, racers would take a Model A Ford, take the body off, narrow the frame rails, hop up the engine, and race. Miller used stamped steel rails of his own design, all aluminum body of his own design, and engines of his own design. His cars were raced in the Indianapolis 500, but found there way to fairgrounds 1/2 mile dirt ovals, and raced as "Champ", cars or "Big Cars". By the late 1930's early 40's more purpose built race cars were showing up. Frank Kurtis revolutionized race car building in America after World War II, by using chrome moly tubing for his race car frames, as well as torsion bar suspension. Sticking with all aluminum body's, his cars were the standard for performance and beauty. By the 1950's and 60's all sprint cars, midgets, champ cars, were tube frame cars, most became "space frame", having a upper rail, and lower rail, much like the frame on your modern day car. Some builders as late as the 1970's used a "Single tube" frame design, re: Steve Stapp, who's cars won races well into the 1980's. By the early 1970's sprint car frames were pretty much the same from builder to builder, using .095 wall, 4130 condition "N" aircraft grade tubing, some frames had different roll cage designs, Grant King's, looked different than Don Edmunds, but the basic design was similar. By 1990 with "Down Tubes", sprint car frames became nearly identical. Frank Kurtis in the 1940's and 50's, used chrome moly tubing, 2 inch diameter for his main "single tube" frames, as did most builders. Here are some reference photo's covering the sport from the 1920's till today, feel free to ask any questions, I'm not a builder, just a long time fan, I raced midgets from 1982 till 1996 in the Colorado area.

Harry Millers shop in Los Angeles, CA in the 1920's.

A Harry Miller Indy car, which also raced as a Champ car, and Big Car.

What was to become a "Sprint car", from the late 1930's.

Frank Kurtis uses 1-1/2" diameter chrome moly tubing for his race car frames after World War II, 1945 to present.

Look close, the #48 is a old pre war car using the steel "Rail frame", design, while A.J. Foyt is in a state of the art (for that time) tube frame sprint car.

You can clearly see the "Space frame" design in these 2 sprint cars from the late 1960's. Bolt on roll cages were to follow, then integral roll cages.

Here's a Steve Stapp frame from the mid 1970's, upper and lower main frame rails are 1-3/8" diameter, .095 wall chrome moly. Smaller tubing for frame uprights, and diagonal supports, were usually .049 wall chrome moly.

Early 1970's, space frames, but bolt on roll cages.
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