Motor Clubman and Special Builder



             No. 2 Lotus XI Series 1 & 2

           By ROLAND DUTT


       The Lotus XI Series 1

IN the 1100 cc sports racing class, few cars have retained the popularity and success of the Lotus Xl’s in their various forms. Although the basic design is now far from new, a Lotus XI is still something to be reckoned with in its class and certainly can be considered a very potent piece of machinery for the club driver. Consequently a magazine with the title Motor Clubman could not be without a description of the handling of such a car. As a result, this month’s track test is a little different from usual — instead of dealing with a specific car on a particular circuit, it covers the impressions gained of two cars and a number of circuits. Sometimes under racing conditions.

The two Lotus’s (or should this be Loti?) concerned were the XI Series 1 and the XI Series 2 and both types are too well known for it to be necessary to give their specifications in any great detail, in any case the various combinations of carburetters, gearboxes, and degree of tune of the engine available make this almost impossible. However, I think the two cars tested can be considered typical of their type. Both cars incidentally although in tip-top condition had covered quite a few racing miles.

The Series 1 was fitted with a 1098 cc Coventry Climax engine, stage two tuned but with a high compression head. In case you don’t know, stage three tuning incorporates larger diameter big-end bolts and in the interest of safety, a 5 bearing camshaft. Gearbox was a BMC A30 with special close ratio gears. Continuing in the wording of the typical classified advertisement, DeDion, discs and wire wheels. The familiar all-enveloping body, which really is as aerodynamic as it looks, gives the car a compact and purposeful appearance. The cockpit is roomy and comfortable for the average driver. If you are on the long side and have to sit on the floor with the minimum cushion, there is about 2 inches of adjustment available to enable the steering wheel to clear your knees. This is achieved by is undoing one clamp bolt and lengthening the steering column. A detachable headrest is fitted -- probably quite effective on the original design which had a wraparound windscreen on the driver’s side only but with full width windscreens it looks rather cumbersome, does not appear to serve any real purpose and tends to obscure rear vision,

The propshaft tunnel which is a stressed part of the structure comes fairly high on the left of the driver and acts as a support without restricting arm movement. Due to the perfect position of the pedals one can heel and toe with the greatest of ease, this with the close ratio gearbox makes changing down a joy.

Ones’ first impression of the Series 1 is the outstanding acceleration for 1100 cc’s particularly at the lower end of the scale. Getting away from the starting line even from a bad position, it is possible to gain several places before the first corner. In spite of the car’s good power/weight ratio from a standing start wheel spin can be kept to a minimum.

The roadholding in general is good by most standards, but compared with the heavier IX or the later Series 2, I would not say it was exceptional. On a medium slow bend one tends to broadside with opposite lock, which of course gives a bit of wheelspin coming out of the corner, with a consequent waste of time. However, on faster bends, the car behaves very much better, diving into the corner with the well known Lotus understeer and the minimum of drift. Control through the corner is maintained almost entirely on the throttle, nevertheless it must be said that the general handling characteristics of the car are deceptive. It is particularly sensitive to the slightest error or ham-handedness and at high speed it is very easy to overdo it. In other words the car is by no means as safe as it feels, as I know from experience. This of course is to be expected when realises the extreme lightness of the vehicle.

The steering characteristics can be altered by quite a considerable amount to suit the individual driver’s requirements. Apart from the usual variations of the tyre pressures, the degree of understeer can be varied by adding or removing washers at the top of the front suspension units.

           On the straight the car is fairly stable and can be driven “hands off” at quite high speeds, but as the maximum approached, particularly if there are any slight undulations on the surface, it shows a tendency to snake. This is very slight, but one can’t help getting the impression that even the slightest relaxation of effort on the driver’s part, and things could very easily get out of hand. I put this tendency down to the front suspension, being of the spilt axle type. This particular car appeared to have rather hard rear suspension, which had no adverse effect on the roadholding, but did not give the driver a very smooth ride. Braking is extremely good and only the most violent braking produced a slight wheel patter, at the front end. After one particular race when the car had been driven very hard and the brakes had consequently become really hot, it was noticed that grease was melting and throwing from the front-hubs, due to the heat generated by the brakes.

Incidentally on the Series 1 there are no air ducts to the front brakes and the fitting of wire wheels does not materially assist cooling of the discs as the wheels themselves are almost entirely enclosed by the body.

Under racing conditions as distinct from tests when one has not the time (or inclination) to look for faults, the general impression gained is that the car handles well, but does require a certain amount of concentration from the driver.

The revs build up with remarkable rapidity and one goes up to the permitted 6000 rpm through the gears with incredible ease. Changing from third into top at peak revs, when really pressing on, brings about a certain amount of clutch slip before the drive becomes solid. This is accompanied by a strong smell of burning clutch lining. Provided that you are just that little bit inside the limit, the car goes round corners literally on rails, and particularly noticeable is the almost complete lack of roll for a sports car. It does however take sometime before one is sufficiently familiar with the car to know exactly what that all-important limit of the car’s cornering ability really is. In the early stages, the driver finds himself taking fast curves well below the car’s capabilities. Of course, as can be expected under such conditions and with such a high cornering speed, the limit is met very suddenly with practically no preliminary warning. It is therefore advisable to really get to know the car and build up slowly to this very critical point.

It is an ideal car in every way for the beginner and a good introduction to high speed motoring. At the same time it is a car to be treated with respect and one that does not permit liberties to be taken.



The Lotus XI Series 2

The Series 2 can be considered the logical development of the 1 and in the course of this development, the various faults of the 1 have been eradicated. It is a more robust and slightly heavier car but nevertheless is much superior in performance to the Series 1. It is possible that it does not possess quite such good initial acceleration as the Series 1. On some circuits of the slower or twisty variety, some drivers prefer the S.U. carb to the more usual Weber to improve the acceleration at lower revs. Although wire wheels can be fitted to the Series 2, the majority have light alloy disc type.

This particular car was fitted with an MGA close-ratio gearbox, which is considerably more robust than the A30 BMC, but also a good deal heavier. Gear changing could not be effected nearly so rapidly on this box, neither was the spacing of the ratios all that could be desired. The clutch was incredibly heavy and brake pedal pressure a good deal higher than the Series 1. The handling of the car is quite outstanding, the roadholding and cornering capabilities being beyond criticism.

Experimenting with tyre pressures, it was found that the best results were obtained with a pressure difference of 4 lbs between front and rear, the front being the higher. The steering has that firm feel and there is practically no kick­back from the road wheels. The bound and padded light alloy steering wheel looks very small indeed, but on driving it fits in well with everything else.

This feeling of firmness, coupled with the high gearing, gives a direct response enabling the car to be placed accurately just where you want it, in a corner. There is absolutely no necessity for any of the dramatic wheel fighting, common to many of the smaller cars. One feels almost relaxed even at quite high coming speeds. Going really fast through a corner at racing speeds, the car remains accurately on the chosen line, with an almost imperceptible amount of drift.

Plenty of throttle is required right through the corner —too much and of course the front-end tends to break away—but even so, you receive a reasonable amount of warning and a slight easing of the throttle and it is instantly under control. The driver never has that odd moment of doubt coming out of a corner when the outside grass verge comes rapidly nearer and nearer. Under the most extreme conditions it is unlikely that the back-end will break away. In fact I would say that when one is familiar with the car, having set tyre pressures and steering geometry to suit the driver, it is definitely the most ‘unspinable’ car I have ever driven.

Winding it up on the straight towards the 8000 rpm mark (which incidentally is off the power curve and not to be encouraged), far from showing any tendency to snake, the car seems to sit down on the track even more than usual. At these speeds there is a tendency for the rear of the bonnet to lift due to the pressure of air trapped inside.

Apart from this, the aerodynamics (or to the uninitiated and old fashioned — streamlining!) must be very efficient as there is no eddying in the cockpit whatsoever and neither is the driver troubled by wind noise. In spite of the very high pedal pressure, braking is really good even from very high speeds, such as the straight at Aintree. Really hard and vicious braking due to an incident at Melling Crossing, caused nothing more unpleasant than smoke from the tyres, not even a twitch of the steering wheel, but the driver had second thoughts about a safety harness if only to keep him in the cockpit.

On either side of the radiator intake are small air ducts for the front brakes and scoops on the undertray for the back. After several races on widely differing circuits, I have never known the brakes to give trouble or overheat. Incidentally on the disc wheeled car, changing the front wheels interferes with the disc brakes and it is essential that a couple of pumps are given to the pedal after the operation to restore fluid in the calipers and brake-lines. I once forgot with disastrous results at the first corner, due to complete lack of stopping power.

The Series 2 is only slightly bigger than the 1, but manages to give an almost big car feel as regards handling. It can be said that it possesses no vices and provided that one remembers that the car is cornering a lot faster than the driver realises, it is a remarkably stable car. To obtain the best results, it is as well to know the proposed circuits and make the necessary alterations to suit that circuit. After all it is only 1100 cc, a fact that the car encourages one to forget. Apart from the obvious choosing of suitable back axle ratio, different carburetters are sometimes more suitable for a particular circuit depending on just what revs you really want the power. This car had the full stage 3 modifications to the bottom-end and a high compression head, but had not been fitted with the 5 bearing camshaft. Although the heavier valve springs that go with this modification had been fitted, no trouble has been experienced with camshaft bearings on the camshaft itself. One cannot fail to be impressed with the roadholding, I once heard one Special enthusiast proudly describing his car by saying it held the road like a Lotus. If he meant an XI he certainly had something. Even under wet conditions it still possesses that little extra.

          I shall probably be unpopular for saying so but I think it is a better car than the later type 17.