Someone mentioned the original Seven had a de Dion rear axle. I
thought a history of the Seven might be interesting. Most of this is
from Dennis Ortenburger's book, Legend of the Lotus Seven.
The Evolution of the Lotus Seven
1954 The Mark 6 This was based on Ford (UK) rather than
Austin engine, transmission and brakes. It would be sold as
components including body, chassis, front and rear suspension,
instruments, windscreen, radiator, and gas tank. The space frame
design weighted 55 lbs and was the basis for Chapman designs
until the Lotus 25. (The welding jig was an old iron bed frame,
which explains why there is barely enough room for the two of us.)
It used a swing axle front suspension which started life as a beam
axle and was cut in half and bushings added. The rear live axle
located by Panhard rod. The engine was flathead Ford Prefect but
engine mounts were offered for Consul and MG-TF engines.
Weight was 1000 lbs, 0 to 60 was 12.25 seconds and oversteer
could be induced at will. Rumors were that a hot MG engine could
push this car to 120 mph.
The Mark 8, 9, and 11 all followed and were advanced streamlined
competition cars. Chapman had planned to produce real cars and
was going to introduce the Seven and the Elite.
"The Seven was the car I dreamed about as a school boy. When I
got the chance to build it, it was the most basic, lightest, high-
performance little car we could come up with...A student's car, if
you will- a four wheeled motorbike."
1957 Chapman takes a week to design the car at home. He
started with the Eleven Clubman with independent front and solid
rear axle. Edward Lewis build a special out of a Mark 6. He
added a De Dion axle, Climax engine and funny coil-over shocks
in the front. The body was cycle fenders in front and looked a
little Austin-Healy 3000 rear. Chapman offered Lewis the first
production Seven in exchange for the special. The Seven is
surrounded by the controversy of this special being the first Seven.
The Seven was based on the Eleven with fewer tubes. The loss of
triangulations was compensated for by the riveted undertray,
transmission tunnel and body sides. Front suspension came from
the Mark 12 Formula 2 car with lower wishbone connected to the
coil-over shocks. The upper was formed by the intersection of the
top arm and the sway bar. The steering rack was originally behind
the axle. (The steering incorporated a negative Ackerman effect.
This gave easily controlled understeer!) The rear was a live axle
located by two trailing arms. A diagonal tube located the
differential laterally and coil-over shocks provided the bounce.
The Seven F used a Ford engine of 40 hp. Spare tire was optional
and tires were 4.50 x 15.
The Super Seven came with the Coventry Climax FWA with 75
hp. 15 inch wire wheels were standard as were tachometer and a
16 inch alloy steering wheel.
The Seven A used the BMC engine from the Sprite with 37 hp.
The car was introduced at Earls Court Motor Show in October of
1957 along with the Elite and sold for $1643. (MGA $2750, TR3
$2665, Austin-Healy 100/6 $3195!)
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