Welcome!
This article will show one way to build a 1:25th scale sprint car to compete in the Scale Open-wheel Racing Enthusiasts organization. The goal will be to set a base line for a scale representation of a USAC style sprint car. I say a base line as detail touches will come later after the basic design proves to be worth building upon. Enjoy :)
BACK STORY
The Scale Open-wheel Racing Enthusiasts grew out of the Miniature Auto Racing Association and has kept with the practice of using factory produced stamped steel and brass chassis in an effort to keep with the principals out lined in it’s Mission Statement. By keeping as many of the basic parameters of the chassis constant it is hoped to provide a level playing field for all who participate. This does present some interesting challenges and compromises in relation to attempting a scale representation of a sprint car. As the build progresses I will occasionally grumble and moan about those compromises, but it must be kept in mind that the basic principle SCORE has laid down is to create a level playing field for all involved.
BASIC DESIGN
It was by accident that the car that will follow was made. My intention was to create a silhouette of a sprint car as accurate as possible with the limiting factors being, the SCORE rules, limitations of scale and my skills. The current SCORE slot cars have their roll cages soldered to the top of the chassis. This in effect cuts off the bottom 4” to 6” (1:25 scale) of the car. For the most part it wasn’t really noticed because the scale tire size chosen is approximately the same as the missing frame dimension. My goal was to make a sprint car frame and use it to straddle the WOMP chassis. This concept requires some parts of the Sprint frame to be removed because of width limitations like at the rear axle tabs. The WOMP chassis is to wide at this point to allow the Sprint frame to fit over them and still be within the 1 1/8”mandated width.
I chose 1/16" Brass wire for the Sprint frame simply because the tracks it would be run on are small and flat. The motor of choice for SCORE is the FALCON 1 and the track power for each of the tracks is either a car battery with a trickle charger or in the case of Pit Road Raceway, a Pyramid PX26 set to 12 volts. The speed achieved by these cars would be within the limits of the brass wire. It will get banged up a bit but it is easier to bend brass wire for the frame than piano wire. For solder it is Radio Shack’s silver bearing#64-305-E although the current part number appears to drop the -E and is now 64-035. The make up is; 1 x Spool, 1.0oz., Diameter 0.015", Rosin Core Silver-Bearing (62%-tin, 36%-lead, 2%-silver) Solder. For flux, Harris Stay Kleen #40002 liquid acid flux or occasionally KESTER acid paste flux SP-30.