Sports Car and Lotus Owner, Vol.   , No.     April 1959

4 DTN: one of the rare fibreglass-bodied Elevens


The Eleven (Series One and Two)   by Mike Costin


THE Lotus Eleven is produced in three forms, Le Mans, Club and Sports, all with basically similar chassis. The Sports version is fitted with a Ford Ten engine and gearbox, the other models with Coventry Climax FWA or FWB power units. The standard gearbox in these latter cases is a Lotus modified BMC “A” series unit fitted with close ratio gears for racing purposes. The final drive unit is also BMC ‘A” series, thereby allowing changes of gear ratio between 3.7 and 5.3 to 1.

Reverting to the chassis, the Eleven first appeared in 1956 with a tubular steel space frame chassis having independent swing axle front suspension and de Dion rear suspension.

Dealing firstly with general maintenance of the chassis itself, starting from the front, the body hinges are rubber moulded bobbins fitted to the front chassis cross tube. These should be well greased at all times in order to ensure correct functioning. Should they become mutilated or broken they can he replaced by un-riveting the outer portion of the undertray in this area and re­riveting it after replacing the bobbin.

The body-fastening hook has a cam arrangement to ensure that the body is held rigidly in position, and the rollers on which this runs, which are situated immediately behind and above the rubber grommets, should also be kept lubricated.

The front suspension on this car was a development of the Mark Nine suspension except for the addition of Girling disc brakes. The half beam axles are modified Ford Popular components hut the radius arms are from an earlier type Ford, the “Y’, model, and are rather lighter.

Points to watch on the radius arm and axle beam assembly are:

(a) cracking from the bolt through the rubber bush in the axle beam where it passes through the channel across the front of the chassis,

(b) cracks in the diagonal down tube where it meets the rear pick up of the radius arm,

(c) looseness of the bolt passing through the radius arm and beam. (Note: It is most important that this bolt be absolutely dead tight at all times.)

The suspension units used on the Series One Eleven were of Girling manufacture in the first instance, but Armstrong counter­parts are available.

The bottom pick-up for the front suspension unit gave trouble in the early days, when it was made up from a piece of 1/2in steel bar; the latter type, which was made from a machined bar of 5/8in diameter, proved quite satisfactory. The anchorage for the top of the front suspension unit also gave trouble, particularly on the left hand side, and this was cured by

(a) thickening up the plate through which the peg top of the suspension unit protruded,

(b) raising the gauge of the top chassis member.

Any adjustment of the front suspension which is required for alteration of ride level should be obtainable at the top or bottom suspension pick-up by either adding or subtracting rubbers and although the amount of adjustment available is quite small, possibly in the region of plus and minus 1/4 in, this actually gives something like plus or minus 1/2 in on the actual car ride level. The normal ride level of 5 in should give satisfactory road holding characteristics, but for people who wish to experiment for themselves ride levels should be raised to increase understeer or lowered to increase oversteer.

The front stub axles are modified Ford F93A, and the hubs are of a proprietary brand modified to suit the Lotus requirements. The hubs should need no maintenance whatsoever excepting possibly the renewal of the Timken taper roller races and the inboard grease seal. A point to note here is that there should also be an outer seal, which is in the form of a light steel pressed cap, and this should be a press fit into the outer race housing. I point this out because on the majority of Elevens which I have seen recently this outer seal is missing.

The steering gear of the Series One Eleven is of the rack arid pinion type, and this again is a modified version of the BMC rack and pinion. This unit should need very little maintenance apart from stripping and re-assembling yearly and adjustment of the end pads by the addition or removal of shims

The steering arms used on the Eleven Series One were of Lotus manufacture, and did present some trouble in the first instances in that the two bosses on which the arms are mounted, which are brazed into the steering arm itself, used to come loose and allow play in the steering. This was evident upon inspection and was easily detected by cracks on the braze at the points where the stubs enter the arm. The rack and pinion is actuated by a tubular steering column which has two universal joints. During overhaul these should be washed in petrol and checked for play, and replaced if necessary.

The rear gearbox mounting and the undertray from the engine bulkhead to the seat back are all highly stressed parts of the chassis and should receive some maintenance attention. It is quite likely in older cars that all the rivets holding the undertray on to the chassis itself have become loose, and this can be repaired either by re-riveting between the existing rivets or better still by drilling out all the old rivets, drilling each hole oversize and re-riveting using oversized rivets.

The de Dion assembly used on these cars was most satisfactory generally speaking, but there are one or two points which should be watched. Firstly the chassis at the rear of the A bracket pick-up on the rear of the prop shaft tunnel should be inspected very closely for cracks. Later chassis have a modification here whereby an angle bracket was inserted joining the right hand vertical member of the rear prop shaft frame on to the seat back tube, which went between the sides of the prop shaft. This would be a worthwhile modification on any chassis which is not already so modified.

The de Dion outer drive castings should be stripped and re-assembled and the bearings and grease seals checked for condition.

The Hardy Spicer unions used on the articulated drive shafts were of 1100 series, and these should be carefully checked for any signs of wear and replaced if necessary.

All of the rubber bushes on the radius rod ends should be checked, but these should have an almost indefinite life and should be discarded if they become perished or swollen due to excessive oil or petrol soakage.

The differential housing casting is of Lotus design, and was developed specifically for the Eleven. The drive shaft bearing housings should have provision for a sealing “0” ring, and anyone having a very early casting in which this “0” ring groove is not machined would profit by incorporating this modification, as it certainly helps to keep the brakes free from oil. The differential assembly itself is held into the casting by eight 3/16in bolts. Should any of the threads in the magnesium housing be damaged then they can be retained by the use of an Armstrong Heli-coil insert.

The Girling disc brakes used on the Eleven should be maintained as recommended in the February 1958 issue of SPORTS CAR AND LOTUS OWNER. Owners of Series One Elevens fitted with discs of chromium plated steel should be careful only to use pad material Ferodo DSI or Mintex equivalent. Conversely, cars with cast iron discs should use Ferodo DS3 or Mintex equivalent.

The twin master cylinders fitted to these cars are the remote tank centre valve type and should be of 3/4in diameter; some early ears were fitted with 5/8in diameter master cylinders. The clutch pedal and linkage is assembled in one and fitted in the car through the hole in the side of the driver’s foot box. It is essential for correct operation that the assembly should be fitted loosely, and then the bolt through the Metalastik-type bush should be tightened up only when the pedal is pulled backwards to the full extent of its rearwards travel. The reason for this is that the only means of returning the pedal to the normal position is by the spring action of the pivot bush, which is of a special double bonded variety. This special treatment also applies to the brake pedal on Series One cars, although a spring push-off is fitted to the brake pedal of Series Two Elevens.

The throttle linkage also should receive some attention, in particular to the ball joints on the carburetter link, as these have a tendency to come undone when the wear becomes excessive.

In early cars the gearbox oil used to leak from the gearlever attachment plate, and this was cured by soldering a short piece of tube on to the top of the plate and then fitting the normal A.30 rubber moulding over this tube and fastening it into position with a Jubilee clip.

The hand brake on the Series One Eleven is quite effective generally speaking, and maintenance should be confined to greasing the cable, adjusting it—if necessary—at the differential end and replacing the hand brake friction pads.

The Series Two Eleven differed from the Series One in many respects. Firstly the front suspension was replaced by an entirely new wishbone-type layout. The chassis was re-designed to accommodate this new suspension and at the same time the rear suspension was also modified, although it bore a very great relationship to the previous year’s de Dion set up.

The front suspension on the Series Two Eleven is completely Lotus in design and utilises only the very minimum of proprietary items. These are the king posts, the stub axle, the hub and the king post bottom bearings. This suspension has proved to be most successful and has remained unaltered even to the latest Formula One car, where it is still precisely the same as on the Eleven but turned back to front. Maintenance on this suspension is confined merely to checking for wear at the stub axle bearings, the top king post ball joint, the bottom king post bearings and the rubber bearings on the bottom wishbone.

The Eleven Series Two de Dion was introduced (a) to widen the base on which the bearings worked and (b) to bring it into line with the 1957 Lotus standard, in order that the cars could be fitted with either spoke wheels or the cast magnesium type. The de Dion is principally the same as for the Series One, but instead of the aluminium grease seals for the outer drive shaft bearings a special seal is now used, which is made of pressed steel approximately 12 thou thick, and this is designed to run on the outside edge of the bearing outer tracks and polish its own line; once it has polished this line it forms a very good grease seal.

On the Series Two Eleven the Hardy Spicer joints were increased in size to 1300 Series, this again to bring the car into line with the firm’s 1957 standards.

The spare wheel mountings on early Elevens were made of 1/2in tube, but these were later replaced by mountings of 5/8in tube.