The design of Electrathon America car 555 (formerly numbered 777) was started in 2002. Over 90% of its parts were modeled in 3D CAD to optimize fit inside the small body. It's monocoque chassis is made of carbon fiber and Kevlar, vacuum bagged around a balsa wood/foam core skeleton. It used our own custom molds, since donated to a local school. There were also a few thin-wall structures where carbon fiber was formed over 1/8" thick plywood. Strength comes from the carbon fiber/Kevlar laminations, and the wood helps to hold it in the correct position.
Most tubular suspension structures shown are made from 4130 Chrome-moly steel with 0.028 to 0.035" wall thickness. This was later found to be too thin for some areas (see article "555 modifications"). All plate steel shown is also 4130.
While it was 90% complete and primered in 2003, the car was only track tested a few times until the summer of 2007. That's when was painted and prepared to travel to Bonneville Salt Flats where it achieved a world record top speed (meeting Electrathon vehicle rules of that time) of 96.4mph on its 3rd of 5 passes. It has competed in several events following. A favorite, being Portland International Raceway in Oregon, on Memorial Day weekends. So far, we have chosen not to run it in small tight tracks, to avoid the close traffic damage that often occurs on those courses.
Here's the car with the top off.
The front (front suspension) mount wall is 20.5" back from the car nose.
The rear (front suspension) mount wall is 32.5" back from the car nose.
The front-wheel spindles (axles) are 31.25" back from the nose of the car.
(not the top of the bolt shown).
This rack & pinion worked excellent and was easy to install. This was an improvement from the original steering design and is available on our web store.
The front edge of the red backrest section is 53.25" back from the nose.
The front edge of the pocketed composit roll bar is 68.5" back from the nose.
The centerline of the rear swing-arm axis is 70.5" from the nose. The white & red handle is the external power shut-off, required by competition rules.
Rear-axle is 7'-11" (95") from the nose of the car.
Kingpin caster angle is 13 degrees from a line perpendicular to the floor. This angle was chosen to add camber (banking angle) to the wheels when turning.
Below is a closer view of the angle shown above.
Motor axle-to-wheel-axle distance is about 16.25". A short distance helps to prevent the chain from derailing in hard corners, since we don't lean like a motorcycle.
Trailing-arm and caliper-mount plates are welded to the back of the spindle assembly.
The three main tubes that form each "A" arm are 3/4" in diameter x, 0.035" wall 4130 (chrome-moly steel).
View showing front mount-point of the left swing arm. Hat-bushings were pressed into the steel tube.
Compare the image above to the one below to notice a nut is on both sides of the carbon fiber wall. These two nuts are tightened together on the wall, to stabilize the pivot bolt. Black plastic spacers are used to consume the remaining space on all mount points. This allows for swing-arm positioning options and more forgiveness (tolerance) when building.
The distance from left-to-right tire centers is about 43" (at axle level).
We run various tire sizes. This one is 20"x1.75".
We usually run 100 to 110 PSI tires.
The rear wheel/tire is back as far as we could put it (with this tire size). The axle is located about 13" forward from the tail.
Finally, an early dimensioned sketch showing body dimensions. While supplies last, this body is available at our web store as part#1437.
We hope you found this useful!