With more short chassis cars than tourers being produced in 1929, the efforts of the Aston Martin works were clearly going towards the sports end of the market. By the end of the year the ‘Standard Sports Model’ had developed into the ‘Four-seater "International" Sports Model’, more commonly known simply as the "International". It was quickly and widely regarded as one of the best light sports cars of the day. The name "International" was coined to cash in on the works’ racing efforts. The appearance of the cars at Brooklands race track and in rallies, sprints and hill climbs all around the country alongside the works team cars, increased the cars’ sporting reputation. The "International" was truly a sports car in the best tradition of the earlier Bamford and Martin cars. Now with twin 1⅛" carburetors it had dry sump lubrication as standard, which kept the temperature of the oil at least 10 degrees cooler than in the wet sump engines. It was fitted with relatively large fourteen inch diameter brakes operated by Perrot shafts at the front. The "International" was expensive but performance was good enough for the motoring press to praise the car highly. A significant amount of advertising was placed in the popular motoring press highlighting competition successes.
The "International" had a similar but dimensionally different chassis to the ‘Standard Sports Model’. Also slightly different, was the brake arrangement, and the gearbox was moved back in the chassis to leave more room in the driver’s side foot-well. These small modifications were typical of the subtle development that all the Bertelli cars went through. This was in part a result of Bertelli driving the cars himself in competition. For example, he would have been well aware that the gearbox of the early cars needed to be moved back; he would have had a pain in his left leg where they constantly rubbed!
Renwick and Bertelli had designed and developed a simple yet rugged 1½ litre sports car. The build quality was very high with the best standard of materials used throughout. The entire car (with the exception of the steering box) was designed and built at the factory (from November 1929, now Aston Martin Ltd). It was very carefully assembled with engines, rear axles and gearboxes all tested on their own dynamometers, after which they were stripped and checked. This made it very expensive to produce. However, the simplicity and elegance of the design made for an efficient little sports car, which had the legs of many of its competitors.
1. Four- seater "International" Sports.
Built on the short chassis, most of the first series cars were bodied by E. Bertelli Ltd. The standard "International" coachwork was a slightly perpendicular open 2/4 seater, with minimal space in the back for passengers. It was characterized by a rather high profile stemming from a tall ‘wet case’ radiator (the shell forming the water tank) which was further emphasized by the 21" wheels. The fuel tank was enclosed beneath the rear of the body and the spare wheel bracketed on to the body at the extreme rear. The exhaust system was taken from the cylinder head in a simple manifold with the downpipe going down inside the bonnet to the tail pipe and exhaust box below the car. The windscreen folded forward from the base, not flat onto the scuttle (with the exception of the "International Le Mans" model).
Specification.
Chassis. Steel channel section, 11’ 6" in length. Tapering at both ends, and to the rear cross tube 8’ from the front requiring 5¾" extensions to the rear cross tube to mount the rear springs. Six tubular cross members and one channel cross member. The fourth tubular cross member from the front, which provides the support for the front gearbox mounting, is now 4" further towards the rear, moving the gearbox back by this amount and giving far more room for the driver’s feet in the foot-well .The drive shafts are correspondingly shorter to the rear axle but longer between the engine and the gearbox. The rear brake lever cross shaft is also now 6" further to the rear of the car and the arrangement of brake rods and levers is different from the earlier cars. An aluminium casting the full width of the chassis supports two brackets for the dashboard and the aluminium clad ½" plywood firewall.
Wheelbase: 8’ 7". Track: 4’ 4".
Engine. The Renwick & Bertelli designed overhead camshaft 4 cylinder 8 valve engine. Dry sump as per the ‘Standard Sports Model’.
Bore: 63.9 mm, stroke: 99 mm, 1495 cc.
Compression ratio: 6.5:1.
Power: approximately 60 bhp at 4750 rpm.
Torque: approximately 55 lbft.
Twin SU 1⅛" side draught carburettor.
Magneto ignition.
Two ‘Autopulse’ fuel pumps mounted on the rear of the chassis.
Transmission. Aston Martin designed 4 speed crash gearbox with straight cut gears, constant mesh main shaft and layshaft, dog clutch 4th speed and reverse. The gearbox is mounted 4" further back in the chassis allowing more room for the feet in the foot-wells. The clutch is now the later type ‘push off’ Borg and Beck with single large coil spring. Ratios: 16.31:1, 10.48:1, 6.43:1, 4.66:1.
Steering. ‘Bishop Cam’ box, by worm and peg.
Wheels and tyres. Rudge Whitworth’ 52mm x 21", well base, 60 spoke wheels with 2⅜" wide rim, fitted with 4.50 x 21" tyres.
Suspension. Semi-elliptic leaf springs front and rear. ‘Hartford’ friction dampers.
Brakes. 14" aluminium drums with shrunk in steel liners and 1⅛" wide cam operated shoes mounted on a single pivot, actuated by rods. Perrot operated at the front. Handbrake operates all four brakes. Rear brake lever cross shaft now 4" further back shortening the rear brake rod. From 1929 the front axle is fitted with a torque reaction cable to prevent wind up of the front axle under hard braking.
Dimensions.
Wheelbase: 8’6".
Track: 4’ 4".
Length: 12".
Width: 5’ 3".
Height: 4’ 4" (hood raised), Saloon 5’ 2".
Weight: 18 cwt.
Fuel tank capacity: 20 gallons.
Performance: approximately 80 mph. 65 mph (saloon).
Price (1932) £595
2. Four -seater Open Tourer.
The long chassis cars were rather heavy for a 1½ litre engine and were not a great success. They were bodied as rather cumbersome looking four door tourers, many with a large trunk over the rear mounted fuel tank. Some had a rather unsightly bulge at the back to enclose luggage, which could be accessed behind the rear seat.
Specification
As International Four Seater Sports, but chassis length is now 9’ 10" and overall length 13’ 4". Weight is 19 cwt. Being very heavy, top speed was not more than 70 mph.
Gearbox ratios: 17.85:1, 11.47:1, 7.03:1, 5.1:1.
Price (1932) £630.
3. Two Door Saloon
Heavier still than the Tourer, the Saloon must have been the slowest of all pre-war Aston Martins; only one example is known to survive. In fact, only one 2 door example was built. It was however, very well finished, both inside and out and was upholstered in best quality ‘furniture hide’. At £595 it was the price of a large family home and was certainly amongst the more expensive medium sized saloons available at the time.
Specification. As four seater tourer, but with full closed saloon coachwork. Price £725.
4. Four Door Saloon
Almost identical to the two door saloon, but with the rear doors hinged at the ‘B’ post (opening the modern conventional way). This did however cost more to build.
Specification. As Two Door Saloon, but the extra cost of making and fitting two extra doors bought the price up to £745.