Auto Racing Memories | Vintage Race Cars

Auto Racing Memories | Vintage Race Cars (
-   General Discussion about Racing History (
-   -   progression of sprint cars (

jAKE5J 02-24-2016 08:10 AM

progression of sprint cars
Hi everyone my name is Jake and im a 17 year old student and im doing a school project for my engineering class. I am currently racing 305 sprint cars and love this sport and want to do my final term paper on it. I need some information on the chassis of the old sprint cars like the type of metal how thick and how it was constructed, more or less i just need some good ol racing designs that maybe failed or maybe are even still in use today. Im having a hard time finding anything online and hope you guys/gals could help me out with the design of some old sprint cars. Thanks Jake!!

Mitch G. 02-24-2016 12:07 PM

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.

Mitch G. 02-24-2016 12:13 PM

Re: progression of sprint cars
From a 1981 Don Edmunds catalog, sprint car frame, 4-bar, cross torsion bar suspension, add down tubes, a few modern changes on pick up points for radius rods, and engine placement, not much different from what they build today.
From a 1982 Circle Track Magazine article, look at the 1930's frame, compared to modern day construction.

Mitch G. 02-24-2016 12:19 PM

Re: progression of sprint cars
Correction, Steve Stapp used a "Spring front design", not single tube frame, my mistake in typing that. When many cars had gone to 4 bar cross torsion, Stapp was till successful with a spring front car well into the 1970's. Other builders used spring fronts, but most had gone to 4 torsion bar design.

Mitch G. 02-24-2016 04:20 PM

Re: progression of sprint cars
Here's a typical mid 1970's 4-bar, cross torsion, design.
This car has the spring front design, "Buggy spring", or transverse spring was used on race cars from the beginning of American open wheel race car design.
In this photo (an Indy car, but used widely on midgets, sprints, and other race cars) you can see the passenger car "Friction Shock", being used along with the more modern tubular shock absorber. Also known as a lever action shock absorber. Nearly all midgets, sprint cars, Indy and dirt champ cars used the friction shock from the late 1930's into the 1950's.

jAKE5J 02-25-2016 06:50 AM

Re: progression of sprint cars
Awesome stuff! I really appreciate your time of sharing your knowledge on this sport. I should be able to use this for a good start for my term paper!

Mitch G. 02-25-2016 08:56 AM

Re: progression of sprint cars
Would love to see the term paper after you turn it in for your grade, it would make a great post on here!

Quick Time 02-28-2016 10:27 PM

Re: progression of sprint cars
Way to go Mitch, this was great. You sure helped Jake with some great history. Proud of you!!!

Mitch G. 03-02-2016 08:04 AM

Re: progression of sprint cars
The progression of the sprint car is sort of unique in American auto racing. Midget racing came about, sort of, with big car fans building miniature versions of their favorite champ car, and racing them as exhibitions, before big car races. The term "sprint car" is also up to debate as to when it started being used on a regular basis. Champ car, what became known as Indy cars, usually raced 50 or 100 lap races on 1 mile dirt tracks, horse racing tracks, or 1-1/2 to 2 mile board tracks, and then the Indianapolis Motor Speedway. As promoters tried to lure the champ cars to run 1/2 mile fairgrounds tracks, and shorter duration "sprint" races, the term sprint car sort of sprung from that era. In the late 1930's, early 1940's and even into the 1950's "Big car racing" referred to "sprint cars". If you read through old racing magazines, the reference to Champ cars, Big cars, and Midgets, is prevalent. Every now and then, you may run into a old time fan who to this day will refer to sprint cars, as "big cars". Neat stuff.

jAKE5J 03-02-2016 09:22 AM

Re: progression of sprint cars
That's something that has always crossed me and my family's mind is the name "sprint car" and how it came to be. It's really neat to see how far the sport has come with set up, safety, and the amount of support the fans have done for the sport. Its one of the reasons why I choose this topic is to show my class that its much more than a "go Kart" that many people assume they are. The information I have so far shows that these machines actually have quite a bit of engineering and skill that goes into all the hard work to make it happen. Once again I really appreciate the help!

All times are GMT -6. The time now is 09:40 PM.

Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.