MGA

GB

When the M.G. Car Company announced its participation in the Le Mans 24-hour race; after a lapse of 20 years, the three cars entered were acknowledged to be prototypes for a possible new production car. Two cars out of three finished (one crashed), and came 12th and 17th in the classification on distance covered; the totals during the 24 hours were 2,084 and 1,961 miles respectively. Nobody will deny that this performance of the model, after the company's long absence from racing, was impressive.
From these Le Mans cars, known as the type EX 182 (a full description of which was given in The Autocar of June 3), has been developed the production series M.G. A. It is apparent that the experiment of Le Mans was considered successful, as the car shows no basic changes from those cars which took part in the race, but detail modifications have been made for normal road use.
Equipped with the 4.3 to 1 axle ratio, the car is capable of nearly 100 m.p.h. in touring trim with hood and side-screens erected. At the moderate price of £884 Os 10d, including purchase tax, it becomes a serious challenger in the 1.5 litre sports car class. Its appearance, with its wind-cheating body, is a complete departure from the shape of previous models from the Abingdon factory.
The four-cylinder engine is basically the B.M.C. B-Series unit, as used in the Magneue saloon. It is equipped with two semi-down draught 1.5 in S.U. carburetors and the compression ratio has been raised to 8.3 to 1, with a peak output of 68 b.h.p. at 5,500 r.p.m. Maximum torque is produced at 3,500 r.p.m., at which speed the b.m.e.p. is 128.8 lb per square inch.

Siamesed inlet ports are used and the short induction manifold for the two carburetors is bolted direct to the face where these merge into a common bore; a balance pipe connects these two short induction stubs. This is different from the Le Mans cars, wherein the induction pons were connected through to the opposite side of the head and an external balance pipe was used on the other side from the manifold. Presumably this extra complication did not give a worthwhile improvement in power output on the production version. The overhead-valve engine, with a bore of 73.025 nun and stroke of 89 nun (1,489 c.c.), has. a sturdy three-bearing crankshaft which runs in white metal thin wall bearings, this type also being used for the big-ends. A heart-shaped combustion chamber is used in . conjunction with in-line vertical valves operated by rockers and push rods from the side-mounted camshaft. This is driven from the front end of the crankshaft by a duplex roller chain. Lubricant is sup plied by an eccentric rotor pump driven by the camshaft and this feeds the oil through a full-flow filter to the main oil gallery, from which the drillings to the main bearings are taken.

Each carburetor is fitted with a wetted gauze-type circular air filter and cool air is ducted to these from a large bore flexible pipe with its entry placed to the left-hand side of the front grille. A high pressure S.U. electric fuel pump is mounted on a chassis cross-member behind the driving seat and draws fuel from the 10-gallon tank. The tank, which has an external filler, is. placed below the floor of the luggage locker between the chassis frame members.
From the engine the drive is taken through an 8 in Borg and Beck single dry plate clutch with six pressure springs and hydraulic withdrawal mechanism.

A standard B.M.C. B-type gear box and combined clutch housing is mounted on the cylinder block at the rear engine plate. It is a four-speed unit with synchromesh on second, third and top. The ratios are: top direct, third 1.373, second 2.21 and first 3.64 to 1. From the top of the gear box casing above the selector forks, a separate casting extends rearwards and contains the mechanism of the central remote control. A short vertical lever rises from this extension and is well placed in relation to the steering wheel. The travel of the change speed lever knob is short, a desirable feature for rapid changes. An oil filler cap, with dipstick, is placed on the left-hand side of the gear box casing and is reached through a hole in the tunnel which surrounds it.
The gear box casing is. extended to reduce the length of the Hardy Spicer propeller-shaft which connects the drive to the three-quarter floating hypoid spiral bevel rear axle. The standard crown wheel and pinion give a ratio of 4.3 to 1, but an alternative ratio of 4.55 to 1 is offered. An orthodox bevel gear differential with two pinions is used.

The front suspension is identical with that of the previous TD and TF models, and was also used on the Le Mans cars. It is conventional in layout, using coil springs in conjunction with unequal length wishbones. No anti-roll bar has been found necessary, and this is undoubtedly because of the low centre of gravity of the car and its mean track of 4ft, which is wide for its size.
The top wishbone Consists of two forgings attached at their inner ends to the cross-shaft of the Armstrong piston-type spring dampers and bolted at their outer ends to the king-pin post. The lower wishbone is a steel pressing consisting of two identical arms bridged by a centre section which forms the seat for the helical coil spring. The upper end of the coil spring fits into a housing formed by an extension of the. main front cross-member, to which is also bolted the conical rubber bump stop.

In common with other M.G. models, rack and pinion steering gear is used, mounted ahead of the suspension unit and connected to the steering arms by a short track rod at each side. A single universal joint is incorporated in the shaft between the steering wheel and the rack and pinion. Like several cars nowadays, the M.G. has, strictly speaking, no steering column, the shaft rotating where a column remains stationary. It is customary to shroud the top end of such a shaft with an extension pressing from the fascia.

Half-elliptic springs are used at the rear, mounted directly beneath the frame side members. They are shackled at their rear ends and controlled by vertical piston type Armstrong dampers bolted to the inside of the frame members. Check straps control rebound and rubber bump stops are mounted on the underside of the frame where it sweeps up over the rear axle.

Disc wheels with ventilation holes and four-stud attachment are supplied as standard, but wire-spoked centre-lock wheels can be obtained as an optional extra. Dunlop 5.60-15in tyres fitted on 4.00-15in well-base rims are used with both types of wheel.

Lockheed hydraulic brakes with 10 in diameter drums and 1.75 in-wide shoes are fitted. Two-leading shoe operation is used in the front drums and leading and trailing shoes at the rear. Actuation is by a pendant pedal mounted on the scuttle and connected. to the master cylinder by a short operating rod. The master cylinder is a duplex unit with a similar pedal for clutch actuation. Mounted in this position, the two master cylinders are accessible for topping up with fluid. The fly-off type hand-brake lever is located between the seats close to the propeller-shaft tunnel and is connected to the rear brakes by cable.

The chassis frame is based on two side members boxed throughout their length and spaced to the full width of the body, which gives a low. seating position because the floor is flush with the underside. At the front end they sweep in to give the necessary wheel clearance for the good turning circle of 28ft, which the designers have provided for easy maneuverability. The frame is given extra rigidity by extensive bracing at the scuttle structure over the clutch and gear box; stiffening of this section is further increased by a tubular cross-member placed under the transmission at The same point. Although it is rather heavy, the frame possesses very good torsional rigidity, which is reflected in the outstanding road-holding qualities of the car.

The body is paneled in steel and the doors in aluminum. Much research work has gone into the design of the body to reduce the wind resistance, and because of this it is a complete breakaway from the traditional lines which have been associated with this make for so many years. At the same time, the traditional M.G. character has somehow been retained, and the front grille is so styled that its classical origin is at once apparent.

Lucas double-dipping head lamps with pre-focused bulbs and blocked lenses have been blended into the contours of the front wings so that they rise above the falling bonnet line. Separate side lamps are placed immediately below the head lamps, just above the swept-round bumpers, which also carry over riders.

Separate bucket-type seats are placed low down between the widely spaced chassis side members and the propeller-shaft tunnel, to the top of which is fixed a permanent armrest. Good access is achieved by the use of forward-hinged wide doors at each side. They are hung on concealed hinges with no exterior handles, the opening being controlled by pull cables in the spacious door pockets. The hood folds away out of sight behind the rear seat, which area is also used for side screen stowage. The seat back-rests are hinged forward to allow easy access to this compartment. An overall tonneau cover can be supplied at extra charge.

Luggage space is provided above the petrol tank and access is from the outside of the car. The hinged lid to this compartment is released from inside the body by a catch behind the passenger seat. The spare wheel is placed horizontally on the luggage compartment floor, and is canvas covered.
Twin six-volt batteries of 51 ampere-hour capacity are located beneath the locker floor, one on each side of the propeller-shaft. . A single-piece bonnet, hinged at its rear end and supported in the open position by a stay, gives access to the engine compartment.

The curved, one-piece, sloping windscreen is provided with grab handles at each comer which add considerably to the stiffness of this fitting and make it completely free from any vibration or other movement. The four sprung spokes of the steering wheel are arranged to give a clear view of the vital instruments in front of the driver. These consist of a 4 in speedometer with dead-beat. reading and incorporating a head lamp high beam warning lamp. To the left of the speedometer is a matching 4 in revolution counter with ignition warning light. A combined oil pressure and water temperature gauge completes the range of essential instruments immediately in front of the driver and a rheostat-controlled panel light, map-reading light and fuel indicator gauge, make up, with the normal range of switches, the functional yet attractive fascia panel.

There is a wide range of optional extras if required. Provision has been made for the fitting of H.M.V. car radio, and others include white wall tyres,.. twin horns, an external luggage carrier, fog lamp and tonneau cover. In the same category are a radiator blind, wire wheels, telescopic steering wheel and the axle ratio of 4.55 to1.

This new car appears to be a worthy successor to the famous and we loved T -types, incorporating many lessons learned in racing. At its price it is a desirable car for normal road use, yet is still suitable for competition in the 1,500 c.c. class. In view of the increasing popularity of sports car racing, there is available from the factory both the information and the necessary parts for those owners who wish to increase further the performance of the A model, in the same way as they could its predecessors.

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SPECIFICATION:

Engine.-Capacity: 1,489 C.c. (90.88 cu in).

Number of cylinders: 4.

Bore and stroke: 73.025 x 89 rom (2.875 x 305in).

Valve gear: overhead, push rods and rockers.

Compression ratio: 8.3 to 1. B.H.P.: 68 at 5,500 r.p.m. Torque: 77.4 lb ft at 3,500 r.p.m. Max. b.m.e.p.: 128.8 lb per sq in at 3,500 r.p.m.

Speed on top gear at 1,000 r.p.m. with 4.3

rear axle ratto, 17.0 m.p.h.

Clutch.-Borg and Beck, 8in single dry plate.

Transmission.- 0verall ratios, top 4.3, third 5.908, second 9.520, first 15.652, reverse 20.468 to 1. Synchromesh on second, third and top.

Rear Axle.- Three-quarter floating with

hypoid drive. Standard ratio 4.3 to 1 (4.55

to 1 ratio available if required).

Brakes.-Lockheed hydraulic. Front two leading shoe; rear, leading. and trailing. Drum dimensions: F, lOin dia. Hin wide. R, lOin dia., Hin wide.

Tyre Size.-5.60-15in on disc wheels.

Pressures; front, 17 lb per sq in; rear, 20 lb per sq in.

Steering Gear.-cam Gears. Rack and

pinion. Turning circle L.. and R, 28ft.

Electrical System.-12~volt by two 6-volt

batteries. 51-ampere-hour capacity. .

Tank Capacity.-l0 Imperial gallons. Oil

sump, 6 pints. Cooling system, 10 pints.

DimenslODs.-Wheelbase: 7ft lOin. Track:

F, 3ft I Hin; R, 4ft Oiin. Length (overall): 13ft. Height: 4ft 2in with hood raised.

Width: 4ft lOin............ Ground clearance: 6in.

Frontal area (hood raised): 13.77 sq ft (approx). Weight, depending upon extras fitted, 1,900 to 2,000 lb.

Price (Basic).-With two-seater body, 595 pounds.

U.K. purchase tax: £249 Os. 10d. Total price

in U.K.: £844 0s 10d.

Opsional Extras.-Provision has been made

for fitting H.M.V. car radio. Wire wheels are available as an extra if specified with order. . Other optional extras are heater, white wall tyres, 4.55 to 1 axle gears, twin horns, external luggage carrier, fog lamp, overall tonneau cover, radiator blind, chromium-plated wheel rim embellishers and telescopic steering column.

Author: ArchitectPage

Road Test Sports Cars from the Fifties