Articles |
Chassis Come Down to the Ground
by Jim Allen, March 3, 2003
In 1965, the space frame chassis was all the rage. If you were
scratchbuilding slot car chassis, you were most likely building
space frames, whose name and conceptual scheme were borrowed
directly from 1:1 sports and racing cars.
On each side of a space
frame chassis are two long rods, arranged above and below one another,
running from axle to axle, front to back. Several short braces reach top to bottom, and
longer cross-members stretch from left to right, connecting the two sides.
The space frame was strong enough for slot racing and wrecking,
and simple enough to picture in your mind and then scratchbuild.
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Typical space frames, about 1965
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By 1967, 2 short years later, all competitive chassis were built flat to the ground,
completely in two dimensions, except for the uprights needed to hold the motor and axles.
This new chassis geometry had its own weaknesses, mostly solved by the adoption of the
U-shaped motor bracket.
As chassis came down to the ground, at first they were narrow, but soon spread like pancake batter
on the griddle - but that's a topic to be chewed over another time.
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Some of the earliest flat chassis, about 1967.
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It may be clear to us in hindsight, but in 1965 it was not obvious how to progress
from the space frame design. Chassis builders recognized that they could lower the
center of gravity by removing the upper rod of the space frame. However, this
weakened the chassis structurally, inducing an up-and-down flex that could
result in the motor's chin (or is that its butt?) digging into the track.
The solution to the flex problem was to solder in diagonal braces. In chassis
builders who were transitioning down from the space frame, we can track the conceptual change,
as each portion of the upper space frame rod was removed, and the chassis was
braced with diagonals. I have collected several of these Transitional Chassis, see the images below.
When the last piece of the upper space frame rod was to disappear,
U-shaped rear brackets appeared in the scratchbuilder's toolkit,
which eliminated the worst chassis flex. Most diagonal bracing disappeared.
The slot car chassis had come down to the ground.
--Jim Allen
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Transitional Chassis Step A
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Transitional Chassis Step B
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Chassis in Transition Step B from space frame to flat.
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