AUTOSPORT, FEBRUARY 10,
THE NEW LOTUS-CLIMAX “ELEVEN”
Exciting New Coventry-Climax-engined car in “LeMans” and “Club” forms—Dry Weight 7 5 /8 cwts
IN view of the phenomenally successful season that the Lotus enjoyed in 1955, particularly in the hands of its designer, Colin Chapman, one might be excused for anticipating that the current model would continue in production unchanged. Yet the indefatigable Colin has produced a new type which is an improvement in almost every important respect. The new model is called the “Eleven”, meaning that it is both Mark XI and 1,100 cc. in capacity. It comes in two versions.
One of these, the “Le Mans”, has disc brakes and a deDion rear axle. The other, the “Club”, is considerably cheaper, and has a normal rear axle and drum brakes. But the chassis, body, suspension units and propelling machinery are identical for both models. Thus, the owner of a “Club” can convert it to a “Le Mans” as soon as he has saved up enough money. The exact prices, incidentally, had not been worked out at the time of writing.
The new chassis frame follows the general principles of the old one, having main steel tubes of 1 in. diameter and subsidiary ones of 3/4 in. size, in 18 or 20 gauge section according to their work. The transmission tunnel is now a stressed member, and is made from 20 gauge strong aircraft alloy sheet. It takes the final drive torque reaction, part of the floor load, and supports the rear engine mounting.
The front suspension follows tradition, being by modified swing axles. It has a lower pivot than previously to give less front roll stiffness and consequently a shade less understeer. There is a new rack and pinion steering unit, with a short rack to bring the ball joints into the correct position for the suspension geometry. The Girling helical spring units, embracing hydraulic telescopic dampers, are shorter than before and have less travel, due to being mounted nearer the centre pivots. The disc brakes are also of Girling manufacture.
At the rear, a new deDion axle saves 10 valuable unsprung pounds. The tube is pierced to allow the articulated half-shafts to pass through, giving them considerably greater length and less deflection for the universal joints. The short tubular shafts are still extensions from the Rudge-type hubs, but are now carried on a pair of taper roller races in a light alloy housing. Two pairs of radius arms locate the axle either side, and one of these is triangulated into an A-frame to absorb lateral forces, rubber bushes avoiding binding in roll. Both the propeller shaft and the half-shafts are of Hardy Spicer manufacture.
The disc brakes are inboard on the “Le Mans” car, but the drum brakes are mounted normally on the “Club” model. The axle of this car is a proprietary component built up from various B.M.C. parts, and takes the same nose piece, crown wheel and pinion as the deDion final drive. The alternative ratios available are 5.1, 4.9, 4.5, 4.2, and 3.9 to I. Thus, all circuits from the slowest to the fastest are suitably accommodated. Similar helical spring and damper assemblies are employed for both types of axle.
The Coventry-Climax engine
is built up in unit with a new gearbox having an Austin A30 case, with Lotus
close ratio gears included in the “Le Mans” specification. The reductions
are 1.23, 1.67, and 2.5 to 1. Two
rubber mountings support the engine low down in front, and a third holds the
gearbox in the transmission tunnel. The cylinder head of the Climax engine
already has an inclination to the nearside, but the engine is also inclined in
this direction to the extent of 10 degrees. This permits a lower bonnet line and
a straight induction pipe from the horizontal twin S.U. carburetors. The
carburetors are flexibly mounted on rubber induction stubs, and the float
chamber is secured on rubber to the frame, with flexible tubes to the
carburetors. This is to avoid frothing of the fuel, due to vibration. The
well-known single overhead camshaft, over-square, light alloy Climax engine is
too well known to require detailed description. For the Lotus, it has a modified
sump and oil intake to allow for the inclined mounting.
REMOVAL is a simple and speedy business, revealing “the works”.
The 4cyl., o.h.c. “over-square” Coventry Climax engine is inclined at
10 deg. to keep the bonnet line low.
The body is even better streamlined than last year’s model. The scuttle is of the same height, but the bonnet and tail slope down more steeply. They both open on pivots at the extreme front and rear of the frame, but the pivots are ingeniously contrived so that. by a cam action, they unlock on being opened to their limit and allow the two body sections to be taken right off. The consequent accessibility could scarcely be bettered.
Much development work has
resulted in a lighter and completely ducted radiator, fed from a smaller air
entry, being entirely adequate for the engine. Cooling drag has been reduced,
and the piping to the scuttle-mounted header tank has been simplified.
Full-sized lamps are now sunk into the front wheel fairings, and covered by
profiled transparent plastic shields. For racing, the passenger’s seat is
covered and a wrap. around screen and head fairing are used. The typical
stabilizing fins have been all but deleted, the head fairing having sufficient
depth to ensure the necessary stability. For short races, a
9 1/2 gallon fuel tank in the
nearside of the body is used, but an extra 11 gallon tank can be installed in
the offside outer body panel. There is no rear tank in the tail, only the
battery and spare wheel occupying that space.
DRY WEIGHT of only 7 5/8 cwts. owes much to the chassis structure (above) built up of 1 in. and ¾ in. steel tubes.
HUB DETAIL: (left) Drive shaft roller bearings are housed in this light alloy casting, to which are attached the de Dion tube and the double radius arms.
The body has two doors containing map pockets. which are horizontally hinged and open downwards. Both seats are identical, the light alloy pans resting on the floor with 1/2 in. Dunlopillo padding beneath the upholstery. The seat squabs have rubberized hair padding. The steering wheel is of duralumin with three spokes, and a leather covered rim. It is attached to a column which turns in rubber-mounted nylon bearings, and has two Hookes joints running at fairly considerable angles. The throttle linkage is extremely sturdy, and the brake pedal has a compensating bar pivoting directly upon it through a small ball race, and operating two master cylinders with a divided supply tank for safety. The hand brake lever is horizontally mounted under the nearside of the scuttle. A new type of rev. counter is driven at one-third engine speed from the dynamo, which is larger and slower running than before.
Some dimensions of this most exciting new 1,100 cc. sports car are: Wheelbase, 7 ft. 2 ins.; track, 3 ft. 10 1/2 ins. (front), 3 ft. 11 ins. (rear); overall length, 11 ft. 2 ins. (reduced 6 ins.); width, 5 ft.; height to top of scuttle, 2 ft. 3 ins.; height of front roll centre, 5 1/4 ins., rear 9 1/2 ins.; tyres, 4.50 ins. (front), 5.00 ins. (rear) on 15 ins, knock- on racing wire wheels. The car has been weighed dry, and without a spare wheel, at 7 5/8 cwt.
In addition, the Lotus XI will be supplied as a road sports car. This model will be fitted with the Ford 100D 1,172 c.c. engine and gearbox. It will have a full-width curved glass screen with windscreen wipers, and will also be available with a hard top.
Most certainly, the new Lotus will be most formidable as a competition car, and the lap records held by the 1955 model should certainly be beaten. It is in all ways a more attractive car than its predecessor, and Colin Chapman is to be congratulated on a most remarkable design.
John V. BOLSTER.
TAIL END (below) of the Lotus body is blunt in profile but, unlike the “snow plough” Cooper-Climax, has rounded edges. DE DION back-end (right) is lighter by some 10 lbs.; this type of axle features on the “Le Mans” car, which also has inboard brakes.
WITH AND WITHOUT:
(bottom) The Lotus “Eleven” in competition form with head fairing and
wrap-around screen in place and (right) without these accoutrements to speed.