 |
LOTUS SEVEN REGISTER |
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the web site for the
Seven made by Lotus between 1957 and 1973
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|
LOTUS SEVEN REGISTER |
|
the web site for the
Seven made by Lotus between 1957 and 1973
THE DILEMMA
FOR LOTUS:
It is said
that every Seven that was produced by Lotus up to the end of Series One
production was sold at a loss. The choice for Lotus was a simple one:
either cease production of the car altogether or radically re-design it,
making drastic cost savings. Influencing their decision was that Club
Racing in the UK was getting ever more popular as one of the entry levels
into motor sport and since the advent of the “A” Series powered “America”
cars, the U.S. market was really opening up. As we know today it was
decided to re-design the car!
Lotus Seven Series 2 Press Photograph.
CHASSIS AND
BODY:
Considerable
cost savings were made by simplifying the chassis and reducing the number
of members, particularly those towards the rear of the car. In addition,
the expensive double curvature aluminium body panels that required
specialist craftsmen, skilled in the use of the English Wheel, were
re-designed and replaced by items made with glass reinforced plastic.
These included rear and front cycle wings (‘clamshell’ wings that were
fitted to the U.S. “America” model had always been made with g.r.p.) and
the nosecone which was of a very similar style to that on the front of
Lotuses Type 18 Formula Junior race car. Further savings were made by not
having the aluminium floor extending under the rear axle and around the
engine bay. A major improvement was that there was now aluminum sheeting
behind the seat backs preventing water coming through to the seats from
the rear wheels.
General Arrangement of Lotus Seven Series 2.
SOURCING OF
PARTS:
Not many
motor manufacturers were happy to sell their car parts in bulk to the
likes of Lotus as they feared getting a bad name for unreliability. John
Standen who was Chief Buyer found that despite this there were good deals
to be had with Standard Triumph. For some years the Seven and other Lotus
models had incorporated front uprights, and trunnions from both the
Standard 8/10 and Triumph Herald as well as steering racks from the
latter.
Inside of first Lotus Seven Series 2 Brochure.
REAR AXLE:
The BMC axle
from the Nash Metropolitan had been installed in both the Eleven ‘Sport’
and ‘Club’ models since 1956 and on the Seven since production began. This
item was used because of its larger brake drums and the wide choice of
final drive ratios it offered. Standen was able to source an alternative
axle from Standard Triumph’s Standard 10 which was both cheaper and
lighter than the BMC item which still offered a choice of ratios (4.1:1
and 4.55:1). It had smaller 7” diameter brake drums which were matched by
using drum brakes from the Triumph Herald at the front. This enabled the
wheel stud spacing to be naturally common to all corners, a feature that
the Series One had always lacked.
Diagram showing Lotus Seven
Series 2 Rear Suspension.
REAR AXLE
LOCATION:
To make
further savings it was important to reduce the number of engineering
operations required on the axle to install it into the Seven. Previously
with the Series One BMC axle location was by upper and lower trailing arms
and a brace to prevent lateral movement. With the Standard 10 axle
location points for the upper trailing arms were already there and it was
decided to use an ‘A’ frame for lower location utilising the differential
drain plug thus doing away with adding any further fixing points to the
casing. So there were two upper trailing arm points and one lower ‘A’
frame location point in the centre doing the job of both lower location
and lateral bracing. Later the drain plug fixing was to be replaced with a
bracket welded to the bottom of the differential housing.
STEERING:
The first
Sevens, like the Elevens before them, had used a left hand drive Morris
Minor steering rack placed upside down. The rack was placed behind the
centre of the wheels and the column had two universal joints and was
routed along the floor alongside the engine block. Towards the end of
Series One production lhd Triumph Herald racks were used in the same way.
With the Series Two more savings were made as the steering column now took
a straight route from the dashboard to the rack now more conventionally
located as a rhd item to the front of the centre of the front wheels.
WHEELS:
The Series
One had used 15” x 4J disc wheels, firstly similar to those used on the
Turner Sports car and later as used on Triumph’s TR3 sports car or 15” x
4J MGA 48 spoke wire wheels as an option. Again, for the Series Two Seven,
Standen was able to source a good deal with Standard Triumph for the 13” x
3˝J items used on the Triumph Herald. In 1960 13” wheels had become the
fashion and had the added advantage of lowering the centre of gravity of
the car, a must for competition events. The wire wheel option was no
longer available.
ENGINES AND
GEARBOXES:
Production
of the Series Two Seven commenced initially with the two basic
engine/gearbox options from the Series One. The original Ford 100E 1172cc
sidevalve unit with associated 3-speed gearbox and the BMC “A” Series
948cc overhead valve unit and associated 4-speed aluminium cased gearbox
either in Austin A35 form with a single SU for the home market or as
fitted to the Austin Healey Sprite with twin SU carburettors in the
“America” model for the U.S. market. The Coventry Climax engine option was
no longer available.
In January
1961 Lotus started to install the Ford 105E 997cc overhead valve unit with
associated 4-speed gearbox from their Anglia car. This engine had been
fitted in Series One Sevens by some dealers for the past year. Being of
over-square cylinder design, it was much more freely revving and more
tunable than the longer stroke BMC “A” unit. In fact it was the chosen
power unit for the Lotuses Formula Junior open wheel race cars, the Type
18, Type 20 and Type 22 which were so successful with the help of Cosworth
Engineering.
In the early
1960s Ford did not have a remote change for their 4-speed gearbox. To get
the gear lever back adjacent to the steering wheel a remote from the
Triumph Herald was used with a wedge shaped adaptor plate along with some
machining of the connecting interfaces. The end product was surprisingly
effective.
Page from 20th May 1961 issue of Eagle Comic.
THE FIRST
SERIES TWO PRODUCED:
Strangely
enough the first Series Two is nothing like I have described above.
Instead it featured a pointed boat tail and raised instrument scuttle
crafted in aluminium. Research seems to suggest that the car had these
features very early on in it’s life, certainly as far back as the early
1960s. Was the work commissioned by the first owner because he disliked
the new Series Two g.r.p. body features or was it a factory prototype? The
use of cycle wings would suggest the former but who knows?
First Lotus Seven
Series 2 with 'boat' tail and 'raised' scuttle.
Photographs
by courtesy of:-
Ferret
Fotographics TEL: 01453-543243
Sources and
further reading:
Lotus Seven
by Jeremy Coulter (198?)
Lotus – All
the Cars by Anthony Pritchard (1990)
The Lotus
Book by William Taylor (1998)
JWW
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