 An extraordinary story accompanies an extraordinary car which is to be sold in Australia on 27 November by Mossgreen Auctions in Melbourne. In 1929, Alan Hawker (Bob) Chamberlain conceived the plans for his own racing car. Necessity was the mother of invention as everything considered crucial was 12,000 miles away which imposed a lengthy wait. Automotive parts were prohibitively expensive in Australia and anything ordered from overseas took weeks to arrive by sea. Young Bob's uncle was Harry Hawker, one of Australia's outstanding pioneer aviators, so it's no surprise that the car had a space frame more usually seen on aircraft. The car had front wheel drive with inboard brakes, four wheel independent suspension and initially used an Indian V Twin motor cycle engine. However, the engine in it today was built by brother Bill who took over development of the racer after Bob crashed it at the 1934 Mt Tarrengower Hillclimb. Bill used the crankcase from a 4 cylinder Henderson Motorcycle but everything else was home made - the foundry taking 37 tries before getting the complex block casting right. The 2 stroke engine had two crankshafts with pistons running in stepped bore cylinders - the bottom being 62.5mm, the top 35mm. The upper pistons opened and closed the inlet ports to allow the supercharger to pump in the gases, while the bottom ones did everything else, from compressing the mixture to opening the exhaust port for the blue haze to escape out into the atmosphere. Tricky stuff, really. By closing the inlet port much later than the exhaust, which is difficult to achieve in a normal two stroke, the compressor was actually able to fill the cylinder well. By running the top pistons on very short conrods (the crank actually ran through a hole in the upper part of the piston !) the ports opened and closed quickly, with long duration opening possible. The swept volume of the lower pistons was 968cc, the upper ones 100cc, giving 1068cc. The crank was machined out of a 6.5” billet and ran in three roller bearings, being linked to the top crank by chain. Conrods were Ford A, but that bit of simplicity was about all there was. There were eight coils to supply spark to the eight plugs ( two per cylinder), and because of the risk of holing a piston with normal plugs, they designed and made their own which permitted 8000 rpm and an ear-splitting exhaust note. This car and its makers are the stuff of legend and in 1930, an Age newspaper article on the Chamberlain stated: “With its bright, shiny, aluminium body, it looks like a smaller edition of the Silver Bullet. It can accelerate to a speed of 80 miles per hours in half a mile and it is able to make a complete hairpin bend at 55 miles per hour with perfect safety. “If the police will let me,” said Allen Hawker Chamberlain, “I am willing to bet 20pounds to a packet of cigarettes that I can go up Swanston Street at 55 miles per hour and without slackening speed, turn completely round and come back down again at the same speed.” We will watch with interest to see whether this unique car is once again used as originally intended. Text Robin Batchelor, pictures courtesy Mossgreen Auctions. |
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A unique racer available down under.
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