The name ’Ulster’ was first used to describe the two seater racing version of the ‘Mark II’ after the 1934 TT race held at Ards in Northern Ireland. The first four production copies of the works team cars were known as the ‘Two-Seater’ and did not yet have the distinctive chassis number ‘U’ suffix. They are however, all regarded as ‘Ulsters’ in everything but name.
The first three cars (chassis numbers LM11, 12 and 14) were built as works racing cars for the 1934 Le Mans, with a lightened chassis and a lightweight two seater body designed by Harry Bertelli, featuring a novel arrangement to stow the spare wheel, horizontally, in the tail of the coachwork. This necessitated a slight widening of the tail around the spare wheel producing the distinctive shape of the bodywork at the rear. The wings were lightweight cycle type, secured to the wing stays with ¼" bolts with rubber washers each side of the wing topped by a large steel cup washer. In view of problems in previous years, particular attention was paid to the way the wing stays were attached to the brake back plates. They sat on beaded leather strips, with rubber filled bronze bushes each side of the wing stay and were secured by a split-pinned slotted nuts.
At the time that these three works racing cars were being built, a fourth car was being assembled as a special order from R.J. Barton, a particularly faithful customer of the company. Between the 1935 Le Mans and the TT a further three cars were built and subsequent to these a further seventeen production cars were assembled. In total, ten works team cars and twenty-one production ‘Ulsters’ were built, with many of them establishing distinguished racing histories. One car was built as an exact copy of the works team cars in every detail to special order for Prince Bira to race at the 1935 T.T.
The chassis and running gear were identical to the ‘Mark II’, but the engine was significantly up-rated. A strengthened ‘bottom end’ using a fully machined billet crankshaft was combined with improvements to breathing at the ‘top end’. This was achieved by increasing the compression ratio by lowering the height of the combustion chamber roof (the same as the earlier ’Ulster ‘specification ‘International ‘cylinder heads), in combination with high compression domed pistons. A high lift camshaft with greater overlap was used and 1⅜" carburettors fitted. These were a special order from Aston Martin to SU*, the bodies being made in aluminium for lightness. The larger 1¾" inlet valves, first fitted to the long chassis and saloon cars to try to improve performance were retained, with shorter and stiffer double valve springs. The better breathing was also assisted by a four into one exhaust manifold, very similar to the ones fitted to the works team cars from 1932 onwards. The power of the engine was thus raised from about 70 bhp for the ‘Mark II’, to 85 bhp for the ‘Ulster’ and the car was able to rev safely to 5250 rpm. Gearbox ratios were also different to the ‘Mark II’, with ratios being closer as a result of a lower ratio between the two constant mesh gears. Each ‘Ulster’ was tested at Brooklands and guaranteed to be capable of 100 mph.
The fuel pumps were relocated to a bracket mounted on the chassis just below the carburettors and a large 17½ gallon fuel tank was fitted above the rear axle directly behind the seats. For the first time, steel braided fuel lines were used from the tank to the pumps and the pumps to the carburettors.
The two seater bodywork, panelled in aluminium to AIACR regulations (see ‘Coachwork’ below), had a very lightweight ash frame, with the bonnet generously louvred (out dented) to assist cooling. It was secured by two leather straps with the quick release ‘ammunition box’ catches. The radiator was painted, (with the exception of two cars), and had simple painted double crimp diamond mesh stone guard instead of the slatted thermostatically controlled shutters. Some cars had larger Lucas LB165 meshed headlamps. The horn was mounted under the bonnet on a bracket over the water pump, keeping the frontal appearance relatively uncluttered. The interior was kept very simple, with deep bucket seats which gave particularly good support to driver and co-driver. Simple panels of leather were tacked to the body frame on each side of the cockpit. A leather bound carpet covered the gearbox and floorboards.
Both the radiator and the dashboard were painted to reduce glare. The dash was fitted with 3" Jaeger ‘reeded rim’ speedometer and rev. counter and matching bevelled glass 2" minor instruments, which included an oil temperature gauge. A longer version of the ‘Mark II’ Rotax switch plate (FT 95) was used with eight switches, which included the magneto and fuel pumps as per the ‘Mark II’, plus switches for both left hand and right hand headlamps and (separately) side lamps and tail lamps. There was also an on/off switch for the dynamo, since, as a three brush unit, it could potentially over charge the batteries on long fast runs, which was relatively more likely in an ‘Ulster’. The steering column lamp controls as found on the ‘Mark II’, now no longer necessary, were replaced by a simple advance and retard lever. No hand throttle was fitted. A distinctive Rotax starter button was also used, working directly on the main battery feed to the starter motor, with the horn button located on the outside of the bodywork on the driver’s side. At least one car also had a horn button fitted by the works on the passenger side so that the wife of the first owner could also use it!
The whole car was simple but business like and very well thought out. The ‘Ulster’ was a superbly designed and built racing sports car, and there is no doubt that the fact that it was so successful was a direct result of Bertelli’s extensive experience building and driving racing cars ever since the early nineteen twenties.
One ‘Ulster’ has been missing since the 1950s. However, it may possibly be accounted for by what is almost certainly an ‘Ulster’ body tub and a few body parts which survive in the USA, which had been built onto a non Aston Martin chassis.