New Spirit at Lotus
Esprit a new 2-litre mid-engined two-seater with Italian styling and a promising future
Autocar, October 1975
by Michael Scarlett, drawing by John Hostler
Elite, Elan, Europa; now Esprit Lotus's latest 'E'. E for effort, since the button on this new design was pressed only 18 months ago, with the prototype being driven after overnight assembly to collect Colin Chapman from Heathrow on his return from the Argentine Grand Prix in January. E for Engineering Advanced Engineering, Lotus, for whom the Esprit represents the first car to come from the work of Colin Chapman and Tony Rudd and their small team of engineers. E for esprit de corps perhaps the Esprit is to be made à Volvo, by groups of men building each individual car complete rather than on a flow production line.
E for efficiency aerodynamic efficiency, as witnessed by attention, almost unknown in most other car makers but typical of Lotus, to aerodynamic details like radiator ducting and the roadholding efficiency of a low polar moment, mid-engine arrangement. E for elegance, even if it isn't English elegance, but Giorgio Giugiaro's. E for excitement with a stated weight of only 18cwt and the 156bhp of the Lotus twin ohc 16-valve, light alloy engine, it has claimed 0-60mph time, one-up, of 6.8 sec, 0-100 in 22.7 sec, and a top speed of 138mph. Besides 'ghost, soul, mind, wit', esprit also means 'spirit', which the car has lots of; driving the prototype at two stages during its early development when it was still not properly soundproofed was an exciting experience which made us look forward to getting our hands on the fully developed car.
You could call it a replacement for the Europa Twin Cam, which ceased being made in the spring. Passive safety requirements were one reason for the end of that stimulating early (and quite successful) experiment in series production, mid-engined sports coupés. The Esprit, though still dependent on an essentially backbone frame, is, like the current Elite, a car with thorough protection against all forms of serious impact. It is also a more roomy machine, with a degree more space for luggage, though not, it must be admitted, as clever in this respect as the Lancia Monte Carlo. Production is planned to start at 10 per week, with an intended maximum capacity at the Hethel plant of 40 to 45 per week. The first public view of the Esprit is on the Ital Design stand at this week's Paris Salon de l'Auto; Esprits are to be shown at Earls Court.
Chassis & body
There is a chassis to the Esprit, a mixture of fabricated backbone like its predecessor and of tubular frame, partly sheet-braced. The backbone extends from its T-end in front, the extremities of which reach upwards like an Oriental dancer's arms to carry the tops of the spring-damper suspension units. The rear end of the backbone tube broadens outwards to swell, as smoothly as space will allow, into the simple, near-fully triangulated space frame which carries the engine, gearbox and rear suspension. The Lotus engine in all its applications (Jensen-Healey, Elite, and some boats) lies on its exhaust side at 45deg. to the horizontal. This inclination takes up room on the left side, but allows space for a bracing tube across the top of the frame on the right, improving torsional and lozenging stiffness.
The body is naturally made the same way as the Elite, in Lotus's still carefully guarded half-secret low pressure injection moulded glass fibre process. Like a toy plastic car kit, it is really two pieces, an upper and lower half, bonded together along the conspicuous waist line a clamshell moulding. Happily, the naturally functional as well as presently fashionable shape of this type of car convex sides aids this two-piece construction; as any pattern maker will remind you, and as a child making a sand castle knows, there must be taper in a moulded shape to allow the mould to be raised, or the part to be extracted. There is at least one interesting difference from the Elite body, which will amuse Marcos owners. To form a roll protection bar immediately behind the seats, the firewall-bulkhead and roll hoop are combined in one diaphragm, with a hole cut appropriately for the short near-vertical window which divides the engine cover and thereby some engine noise from the cockpit. The Marcosian feature or perhaps one should say De Havilland Mosquito-ish one is that this bulkhead cum hoop is cut out of three pieces of 3/4 inch and 5/8 inch marine plywood. Possibly to anyone other than an engineer, a carpenter or experienced handyman, that may sound a little dubious; the point is however that in both compression and shear, the strength-to-weight ratio of plywood is very good.
At the front of the cockpit there is a box section across the car running between the bases of the A-posts and carrying the steering column, scuttle structure and door hinges. The centre tunnel also picks up on this beam. To prevent sides caving in during a crash, stout extruded aluminium-alloy narrow-box sections in the doors attach to the hinges in front and to burst-proof locks at the back, so that those inside are near-surrounded by both vertical and lateral rings of strength. The door beam extrusions have slots to carry the window lift motors and window frames another typical Lotus multiple function use. Triplex laminated glass is standard (tinted is optional), Solbit-bonded for the flat windscreen.
Another piece of aircraft inspiration is seen for the radiator, inspired perhaps by Tony Rudd's memories of Lancaster bombers he once flew. It is a bonded Covrad aluminium alloy type, unusually long and shallow, and mounted in a moulded space near the rear end of a venturi-like profiled plastic pod which hangs underneath the nose, bolted to the underbelly, and expanding in size from the small entrance as it nears the radiator. The radiator itself has a Covrad electric fan, thermostatically switched, which is placed at the hot end, where the water from the cylinder head enters. There is a 20 deg. C. drop in temperature across the length of the cooler, which speaks well both for the efficiency of the layout, and for that of the radiator; the similarly made (if not similarly shaped) Covrad type in the Elite has proved very successful, encouraging Lotus to stick with this supplier and material. Compared with almost all other cars, radiator air is thus ducted truly smoothly, and allowed to escape without any obstruction, or any tendency to heat up the front bulkhead.
There are two 'lids', the nose one which exposes spare wheel and some luggage space suitable for camera cases and squashy overnight bags, and the rear, gas-strut counterbalanced, which, released from the driver's door frame allows you to get at the 7 cu ft boot and the dip stick, the latter without disturbing the engine cover. The cover is formed like a cap over the power unit. It can be slipped sideways out of its hinges and removed for the best access to the cylinder head. Persuading flat 'bonnets' to shut properly on both sides when their naturally flimsy shape makes them determined not to is difficult. Lotus have got around that bother this time BMW-style, by requiring the driver to close a lever under the facia which pulls the bonnet (the nose one) shut.
The two metal side tanks are best filled separately, in spite of their cross feed. They carry a maximum of 7.5 gallons each, and live between the bulkhead and back wheels.
The headlamps are two-to-a-side (halogen optional) and carried on a swing-up panels which are raised by connecting-rod linkages, electric-motor driven. The wiper is another single-arm type from this manufacturer, with a pantograph arrangement, which, thanks partly to the near-square proportions of the flat screen, clears a claimed 86 per cent of the area, compared with the minimum 80 per cent nowadays required by regulations.
Bumpers are mouldings for Europe, to which the Esprit is being introduced first, and will be foam-filled polyurethane for America.
Front-rear weight distribution of the car's 2,015lb unladen weight, with a half-full tank, is stated to be around 41.5/58.5 per cent.
Suspension, steering and brakes
At the front, Lotus have at present made use of Opel Ascona parts in the conventional double wishbone arrangement, which as this is the original Ascona, includes the anti-roll bar as part of the bottom wishbones (the latest Ascona relieves the anti-roll bar of location duties). One reason for adopting the Ascona parts, besides reducing cost for Lotus, is the brake disc which comes with it, which can be changed for a ventilated disc also used on some Asconas (should future developments demand it). The steering rack and pinion is an Elite one, with a shorter stalk for the opinion, and more quickly 'geared' steering arm geometry.
With no need to clear any rear seat pan, the Esprit is allowed to use a tidier version of the downward-offset Elite back suspension. The upper link is formed partly by a fixed length drive shaft. There is a new rear upright casting, which straddles the transverse bottom link centrally (where on the Elite the link is at the back of the bottom of the upright); the coil-spring damper however still holds the upright at the back. This bottom link is on its own. There is again a length fabricated diagonal box member fixed rigidly to the bottom of the upright by four bolts, but centrally disposed about the drive flange axis instead of below as on the four-seater. It forms a triangular member with the drive shaft, and because of that solid fixing to the upright, relies on the compliance of the inboard flexible bush to avoid any need for it to twist when the suspension deflects. By fitting the spring damper units with clips which hold them in the normal laden weight length during assembly of the suspension, ride height and attitude is fixed correctly when the inboard bushes are tightened, thus providing a small but Lotus say useful effect on these two variables.
The rear brakes, also disc, are inboard, relieving the suspension of any brake twist effects. They are larger than the front only because they have to clear the final drive sideplate bosses. The fact that it is inboard of course also takes away any drive twist effects, though not simple forces due to the same influences. At first, Lotus could not interest British brake makers in providing what they wanted in calipers; the German Teves concern were more than helpful instead, making exactly what was required. Late in the day, Girling offered to adapt the Lancia Beta caliper for Lotus, a quite hefty recasting being needed, at much lower price than the German one; the Girling one is accordingly fitted now. Each is bolted to a curious limb-like casting each side of the transmission; these double as rear engine-gearbox mount legs (Tony Rudd calls them the 'dinosaur's ribs' though they would suit only very young dinosaurs, since Lotus do not go in for the unnecessarily mammoth). Hydraulics are twin circuit, without a servo.
Elite drive shafts and hubs are used, with the exception that the studding is different, to suit the Wolfrace GKN wheels. In the best interest of handling and traction, wider wheels and tyres are used at the back than at the front 195/70 VR14 on 5.5 inch front with 205/70 VR14 on 7.5inch rear on the Esprit 700, and 205/60 VR14 on 7inch rims front with 235/60 VR14 rear on the Esprit 701, these being the most important differences between the two type numbers. The tyres themselves are steel-braced radial-ply tubeless, probably Goodyear G800+S Grand Prix, though Dunlops were also under consideration.
The only differences between an Elite engine and an Esprit one are tiny. The 95. 28 x 69.24mm, 1973cc light alloy unit is carried by two side mounts, plus two supports already mentioned for the gearbox. It has timing marks on the flywheel (where the Elite ones are on the front of the crankshaft) so that you can see them more easily and the water outlet elbow is on one side instead of forwards, because of the bulkhead. Lotus claim that the engine, a zestful unit spoiled only by too much harshness caused partly by an inadequately stiff crankcase, has been refined 'by the experience gained from over 15,000 units'. Its four valves per cylinder now open to the orders of what the maker's call their E-camshaft, which in sample drives we have had in both an Elite and the prototype Esprit, gives a most welcome and noticeable fattening to the middle of the power curve. The unit has passed American emission tests in the Elite; Lotus have an extensive and up-to-date emissions laboratory, which has helped them in this respect.
The transmission is bough from Citroen, who used it on their remarkable, now-abandoned Maserati-engined SM sports coupé. Citroen have guaranteed Lotus at least five-years' supply of this fine transaxle, which has five speeds, all indirect. It is mated with the Lotus engine via a Lotus-made bellhousing, which joins on the centre-line of the differential. Using the Citroen one plus an adapter plate required too much precious length; Lotus bore their bellhousing in situ with the assembled suitably protected transmission quite a game, but it works. The gearchange uses a rod to select the gears and a cable to work the across-the-gate movement. Unlike the Citroen-Maserati there is not a clonking gate, just a free lever, which provides one of the very nicest mid-engine gearchanges we have so far met.
Very careful choice of engine mount Silentbloc blonded mount Silentbloc bonded mounts has ensured that there is just the right amount of throttle and clutch cushioning, at any rate on the prototype, without what an American importer calls 'Lotus leap'. This was obviously a tricky job at the back mounts on the transmission, which because of the need to avoid any undesirable influences on the camber of the suspension (via the drive shaft) had to have very stiff compliance laterally, but relatively slack movement vertically. Maximum revs are limited to 7000rpm as before with an ignition cut-out, allowing speeds in the intermediate gears of 40, 60, 89 and 120 mph in the case of the Esprit 700 fitted with the higher 4.375 one.
At the Motor Show, the Elite will be seen for the first time in 504 form, with the Borg-Warner Type 35 automatic gearbox. The same option will eventually be offered on the Esprit 704, since Citroen had got together with Borg-Warner to adapt the Type 35 to their needs in the SM. A 703 Esprit would be a power-steered one, which seems unlikely at the moment since the car does not have steering that can be called heavy.
Most notable feature of this is the somewhat 'dream-car-like nacelle for the instruments. It is a printed circuit affair, connected to the central loom running down the backbone by a plugged single leg. Cleverly, changing from right to left hand drive on the production floor is basically a matter of swapping the lidded glove locker with the nacelle (and moving the steering of course), which each have similar fixings. The top of the nacelle forms a cover which can be removed for minor servicing, like bulb replacement.
Each wing of the cluster carries switches lamps, panel, interior lamp and hazard flashers on the left, and the simple two-lever heater control plus blower fan and rear defroster on the right. On the left side, there is a lone air outlet to cool the driver's face. Flanked by oil pressure and water temperature on the left and by fuel gauge and battery volts on the right, the two main central dials are a tip speedometer reading to 160mph and an 8000rpm electronic rev-counter. The trip reset is in between, and instruments are Veglia-made, from Italy.
Seats are typical of this type of car couch-like, permanently reclining without any rake adjustment; the steering column is at the moment fixed too, rather than telescopically moveable, and the only adjustment available is of fore-and-aft seat position, with a ramp to lift it for shorter drivers. There is a useful range of this last movement, but no great amount of space behind the seats when a tall driver is using the car, as in other mid-engined coupés.
The view in front is extraordinary the first thing you can see over the bottom of the screen rail is rushing road; this is not because the rail is too high, but because of the shortness of the drooping nose. Screen pillars are naturally quite thick, for structural and safety reasons, but do not block vision as much as they would have done on the original Giugiaro proposal, which had a shallower screen. Lotus changed the screen rake to a more practical angle.
Design history in brief
The first Esprit was a Giugiaro design study shown at Turin in 1972, the result of a conversation between the stylist and Colin Chapman at the previous Geneva show. It had the entire tail lifting up and the steeper screen. But design and development of the car is the work of Tony Rudd, Engineering Director in charge of Advanced Engineering, and his team, with Chapman intimately involved the whole way through. It is very much a team, each member doing the other's work at one time or another, typically of the much healthier atmosphere of a small concern compared with a huge department of a much bigger company. When the first road-going prototype was being assembled in January, everyone was hauled in to building, including Ralph Bellamy who was supposed to be getting on with other work for the rear end of Lotus Grand Prix cars, and Rudd. It was finished a 1am, leaving at 4 in company with an Elite to be driven to London Airport to meet Lotus chairman Colin Chapman, who was returning from the Argentine Grand Prix, so that he could drive it back to Norfolk.
Prices were to be announced after this went to press; this should be the cheapest Lotus. Having driven only the prototype, we should not talk in detail about impressions of the Esprit, except to say that regardless of inevitable noisiness in a machine still in the early stages of development, it clearly has the makings of one of the very best Lotuses there has ever been very fast, very safe, and very great fun. We look forward to Road Testing it.