Tests and Reports

The Rover "Scarab"
We Run the “£85” Mystery Car to Earth and Present Our Readers With the Outline of a Very Interesting Newcomer

Light Car and Cycle Car, 4th September 1931

For some month the deepest secrecy has been maintained concerning a car of unorthodox but practical type with which the Rover Co Ltd, Coventry, have been experimenting, and which will probably make its debut at the Show. It was not until the publication of “The Motor” last Tuesday that some real indication of the character of the car was revealed. Pursuing independent lines of investigation, we have successfully run the Rover Scarab - as it will be called - to earth, and are now able to supplement the information already published.

In Brief
8 hp, 2-cyl., air-cooled engine at rear, in unit with plate-clutch, three-speed gearbox and bevel case. Four-wheel brakes and independent suspension for each wheel. Four-seater body with hood, side curtains, tools, etc.

Seldom in the history of the light car movement has more curiosity been aroused than that caused by the announcement made month ago of an £85 “mystery” Rover car. Dame Rumour soon became busy, and, assisted by conjecture, the mystery was deepened. We ourselves were able to throw considerable light on the main features of the car, but so carefully has the secret been guarded that is was not until last Tuesday that any authentic details were actually available. These appeared in the pages of our associated journal The Motor. Realizing the widespread interest which the car has created, The Light Car and Cyclecar has taken the process of investigation a stage farther, and we now supplement the details which have already been made public, and publish a cutaway drawing (Remark: ⇒ see page 'Technology') of this car which, if not correct in every detail, will certainly serve to show the general principles which have been adopted and the manner in which they have been carried out.

At the moment the existence of the car is still officially a secret; thus at the luncheon given by Henlys Ltd, to Rover distributors on Monday last, the car was revealed for the first time, but is was surrounded by a barrier so that none should have access to it, and it reposed on a revolving turntable so that although an excellent impression was gained of its “externals” no clue was given as to engine, transmission and so on.

It was clear, from the conversation which one heard going on around one, that even the distributors themselves have been unable to guess the secret; in fact, the car will not officially be disclosed in its details until the eve of the Show.
The newcomer will be known as the Rover Scarab - a title which at once gives the atmosphere of mystery which has surrounded the production of the car and which, at the same time, conjures up visions of its magic qualities. In considering it in detail one has to take into account first the low price at which it will be sold and, secondly, the ingenious specification which reveals how ideas which were current 10 years ago have been brought up to date and perfected.
In brief, the Scarab represents a cross between the perfect cyclecar and one of the best conceptions of modified light car design which have so far been put forward. Its main essentials are a twin-cylinder, air-cooled engine placed at the rear and built in unit with a plate clutch and three-speed-and-reverse gearbox, the final drive being by short carden shafts to the rear wheels. The principle is not new. It has formed the theme of many articles in The Light Car and Cyclecar.

It is, perhaps, more in the details of the conception as a whole that the Scarab stands out pre-eminently, for not only is is unorthodox in the light of the present-day practice, in so far as engine and transmission are concerned, but it incorporates a novel suspension system, in which one of the highest ideals of the designer has been attained, namely, the elimination of unsprung weight, to a degree which hitherto has been almost unattainable in light car design.
The tout ensemble is striking, as our heading photograph shows; moreover, the car boasts of extraordinary roominess, it being possible for two adults comfortably to be carried in the front seat and two at the rear. Owing to the position of the engine and the absence of a propeller shaft, the floor of the car is low. thus adding materially to the comfort and roominess of the vehicle.

No Ugly Overhang

The designer has achieved an outline which is very difficult to attain when a rear engine is employed, the rather ugly overhang at the back being conspicuous by its absence and the whole car presenting only a degree of unorthodoxy which tends to distinguish it as something entirely out of the ordinary - something that marks quite a new era in the design of small, powerful and economical light cars.
Before going on to describe the model in detail, and for the benefit of readers who may be new to the cheapest form of motoring, we should explain that the Rover company have a wealth of experience behind them in tackling a car of this type. In 1918 they struck entirely fresh ground by producing an 8 hp twin-cylinder, air-cooled car, which quickly attained popularity and which found many buyers, even at a price which would be considered almost exorbitant in these days, namely, £300.

Not a Revised Rover Eight.

In some quarters it has been suggested that the Scarab is merely a revised edition of the Rover Eight. This is not the case; in fact, we would go so far as to say that the Scarab does not incorporate in its make-up any part previously used in the construction of a Rover car.
Now for the mystery car itself. We cannot do better than describe, first of all, the very convincing power unit which, as we have said, is housed at the rear. One of the accompanying photographs clearly shows the curved bonnet at the back. This is held down along its lower edge by two ordinary bonnet fasteners and fits over tongues at the top. Louvres permit of easy exit for the air stream, which, drawn up from under the car by a fan, is ejected through them after passing over the engine.
The bonnet fasteners having been undone, the bonnet itself is lifted away, and even a casual glance suffices to show the extraordinary degree of accessibility of the whole unit.
The cylinders, which are well ribbed and, axially, slightly staggered, are set at an angle of 60 degrees, the timing case, of course, being at the rear. The cover of the timing case carries the Lucas coil unit complete, the starting dog and the driving pulley mounted on the end of the crankshaft, for the dynamo and the fan.
The dynamo is on the near side of the engine, and is pivoted at its base to lugs forming part of the crankcase casting. At the top the instrument is secured by a single slotted link at the rear, so that found on more conventional vehicles and enables a pulley mounted on the end of an overhead shaft. Support for this shaft at the rear end is provided by an aluminium casting forming an extension of the tappet case, whilst a special bracket over the clutch pit carries the shaft at its forward end. Supported in ball bearings, the shaft carries at this end a powerful four-bladed fan which directs the air stream across the cooling fins and maintains the correct running temperature. The fan runs at engine speed.

From the foregoing it will be seen how very accessible are two main points of adjustment, namely that for the triangulated belt drive and that for the distributor; the latter is driven off the end of the camshaft.
In the past it has been customary to follow motorcycle practice with regard to lubrication when applying air-cooling to four-wheeled vehicles; in the Scarab, however, pump lubrication is provided, and a gauge of conventional pattern on the facia-board is fitted. In this connection the generous size of the sump is worthy of comment, as is also the accessible drain plug on the near side. The dipstick is situated on the near side, the curved end of the stick projecting upwards between the dynamo and the timing case; on the opposite side of the casting there is an oil filler with a quickly detachable cap.

Overhead Valve Layout.

The valves are of the overhead type, operated by push-rods, the latter being totally enclosed in tubes. To ensure absolute oil-tightness, each tube is of telescopic pattern, the upper member being cupped so that under the action of a helical spring it fits snugly over the base of the rocker box; a washer is interposed between the cup and the box. The push-rods are cupped at their upper ends and a thick oil-absorbing washer surrounds each push-rod where it emerges into the rocker case. The rockers themselves are of very sturdy construction and have suitable oil holes.
Adjustment for tappet clearance is by a set-screw and lock-nut arrangement, forming part of the rocker assembly. The rocker boxes for the inlet valves differ slightly from the exhaust in that the complete assembly, including the valve spring, is enclosed. This ensures adequate lubrication of the inlet valve guides. In the case of the exhaust, however, the spring end of the rocker, together with the valve spring itself, is exposed, so that adequate cooling is ensured. The rocker box covers are held in place by light wire clips and can be removed in a moment.

Cylinders Easily Lifted

Following usual practice, the cylinders - of cast-iron - are secured to the base chamber by four nuts, and, owing to the adequate clearance all round, the cylinders can easily be lifted for decarbonization. A short induction pipe bridges the two cylinders, and the Amal car-type carburetter is clamped direct to the induction pipe midway. Fuel is conveyed to the carburetter by means of a flexible, heavy-section petrol-proof pipe from a petrol tank slung immediately above, the upper side of the tank forming part of the bodywork.
A detail of the car worth mentioning, and which goes to show the care which has been exercised in the design, as a whole, may be quoted. It concerns the strangler control, which takes the form of a wire passing round the pulley fixed to the side of the body and which is then guided around the off-side wheel-arch in a tube, the wire finally emerging in the form of a sliding-bolt control on the body member below the driver’s door.
For £85 one scarcely expects to see refinements, but on the Scarab an electric starter is provided as a standard fitting, and it is arranged, moreover, in the orthodox way by bolting it to the clutch housing. The starter is operated by a button on the toe-board of the car and the power is supplied by a six-volt battery housed just behind the dummy radiator at the front and on the near side.
The sparking plugs are placed forward, where they benefit by the full blast of the air stream from the fan, but they are, nevertheless, easily accessible with an ordinary spanner. The exhaust pipes sweep down to a common silencer set transversely below the rear-frame cross-member.
The drive is taken through the clutch to a three-speed-and-reverse gearbox, thence to a bevel box incorporating a free-wheel-type differential, the final step being, as we have said, by short carden shafts to the rear wheels. These shafts are, of course, fitted with universal joints, spring-loaded covers being employed to prevent oil leakage.

Brakes of Contracting Band Type

Close up to each side of the bevel case there is a brake drum of generous proportions encircled by a contracting band. The pedal operates the off-side band and the front-wheel brakes, which are of the internal-expanding type, whilst the lever takes effect on the near-side transmission drum. Instant adjustment of the band is provided by knurled hand wheels which project from the rear of each brake assembly and which can be easily reached with the bonnet raised.
We now come to one of the most interesting features of the Scarab, namely, the suspension system, and in this connection we need hardly remind our readers that it has been the objective of many designers to reduce unsprung weight to a minimum. This is no theoretical consideration; in the case of an ordinary back axle, for example, the whole of the axle casing and the mechanism within, together with a certain proportion of the torque tube or propeller shaft, as the case may be, is unsprung, since the road springs rest on the axle.

A Real “Suspension” System

In the Scarab the ideal has been approached by suspending the entire engine and clutch unit, and the rear end of the frame, from a floating transverse member which is carried at each end on a very heavy-section helical spring taking its seating on a platform adjacent to the wheel hub.
In effect, the springs and the saddle act as a bridge, the engine and the frame to which it is attached being hung, as it were, from the keystone. A further advantage of the arrangement is, of course, that it provides independent springing of each rer wheel and enables rough sections to be negotiated without any discomfort to the occupants of the car.
To ensure correct location and alignment of the road wheels, there are transverse radius arms on each side. These radius rods incorporate shock-absorbing devices at their inner ends, which are secured to the engine-gearbox unit. The outer ends are anchored to the extremities of the platform carrying the springs.
Central control is used, and both brake and gear lever fall readily to hand. The gear lever works in a gate and the selector rod runs centrally below the floorboards and passes through the bevel housing.

On taking one’s seat in the car one is immediately impressed by the degree of comfort, roominess and protection which the bodywork affords. Owing, as we have said, to the low-loading level, legroom is unrestricted, and the overall height of the car is kept down. The front seats themselves are of the separate adjustable semi-bucket type, that on the passenger’s side tipping up so as to give easy access to the rear seat. When the cushion of the latter is removed it discloses a trap-door which gives access to brake controls and so forth, and also discloses two deep and roomy lockers, which are sunk in the form of wells at each end.
The radiator is, of course, of the dummy-type, the pedals being arranged just behind it and alongside the battery. The best possible use has been made of the spare space, however, by using it also to accommodate the spare wheel, which lies in a horizontal plane, just beneath the dummy bonnet and which is reached by bodily removing the bonnet itself.
Finally, a word as to the steering. Although this is relatively high-geared, it is, nevertheless, very light; the fact that the load on the front wheels is not nearly so heavy as with a conventional car probably accounts in some measure for the ease with which the front wheels can be controlled.

General Equipment

The general equipment, considering the price of the car, is generous. It includes a really serviceable hood, side screens, a three-lamp lighting set, tools, starter, chromium-plated V-type dummy radiator, two doors, and so on.
As to performance, we have no hesitation in saying that the transmission system is, in practice, quite satisfactory. The acceleration is good, and at between 50 miles and 55 miles an hour the car rides as well as at low speeds. Owing to the weight distribution, the brakes are surprisingly effective and, thanks to the position of the engine and the careful cooling arrangements which have been adopted, there is no suggestion of “engine smells” in the car, even when the hood is raised.
The new Rover Scarab promises to become one of the most talked about cars at the Show; at the earliest available opportunity we shall give our readers the benefit of our experiences of an extended road test. The price of the car - although freely quoted as £85 - has not yet definitely been settled.

© The Light Car and Cyclecar