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Engineering and Design
Designing and building your own car is very different
than assembling a kit car. Besides designing the overall body, I
faced several other engineering and design challenges:
• Front Suspension:
The 1937 Cord front fenders were originally modeled
from early streamline aircraft wheel covers. The deep pontoon shape
features provide little room for modern suspensions. The challenge
I faced was to find a suspension that could fit under the front fenders.
Two candidate suspensions provided the correct geometry. They were
Corvair and Pinto. I ended up picking Pinto and proceeded to model
the geometry on the computer. I explored the effect of upper arm
location and camber, roll center and tire scrub. In the end I picked
a compromise that provided minimal camber change (excellent cornering)
and minimal tire scrub (minimal tire wear).
• Retractable Headlights:
Original 1937 Cord headlights were raised and lowered
individually with a crank in the cockpit. The original design is
complicated and inconvenient. New design is electromechanical featuring
off-the-shelf limit switches (Digikey) and miniture DC motor and gear
box (McMaster Carr).
• Convertible Roof:
Designed a convertible roof mechanism that completely
disappears within the body of the car. Major design contraint was
the rear cowl support/roll bar. I worked around strucure by separating
roof frame and roof fabric.
• Frame stiffness and strengh:
Performed FEA on similar frame to ensure safety and
maximize torsional stiffness. Performed Instron tensile tests of
weld samples (arc weld). Achieved 90% of ultimate strength of parent
material. All critical welds feature reinforced plating.
• Front Brakes:
The Pinto front brakes feature relatively small discs.
The larger the disc, the greater the stopping power. Stopping power
is much more important than engine horsepower. To
maximize my stopping power I replaced the Ford Pinto discs and calipers
with 10 inch diameter Ford Granada discs and calipers. I designed
and engineered the adapter bracket that allowed the Granada caliper to
be attached to the Pinto spindle. Stress analysis showed a safety
factor of four assuming 1 G deceleration and entire weight of car is applied
to the front suspension.
• Windshield Wiper:
Converted standard windshield wiper motor and linkages
into counter rotating windshield wiper blades system (like old Corvette).
This was done for aesthetics as it looks very cool.
• Gas Tanks:
Designed and frabricated composite dual gas tanks located
behind the seats. Challenge was to find materials that were immune
to both gasoline and alcohol. Currently Minnesota gasoline has 10%
alcohol. It turns out that alcohol is pretty agressive. Used
polyvinyl ester resin and fiberglass to fabricate tanks. Sealed
the inside with an aircraft quality polysulfide compound. Performed
accelerated life test on sample material to verify alcohol immunity.
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