P'art of the day: Maserati "Birdcage" chassis

Todays p'art is a tribute to Italian racing pedigree of the late '50s and early '60s, the reason the Maserati Tipo 60-65 were nicknamed "Birdcage"

While the majority of racing cars from the era used sheet metal "tub" chassis of steel or aluminium the Birdcage utilized a spaceframe chassis of cro-moly steel. Chrome Molybdenum Steel is a metal with an excellent strenght to weight ratio. It is typically referred to as aircraft tube as its used extensively in aviation. Its also used in AK-47 recievers.

The Birdcage was consructed from over 200 individual tubes, between 10 and 15 millimetres in diameter. The beauty of this construction is that because all the tubes are joined at their ends, they only experience tension or compression, forces that tubes are highly efficient at taking. With no bending forces to worry about the engineers could specify an extremely thin wall thickness, further lightening the overall structure.

However there's no such thing as a free lunch. The reason the Birdcages adversaries used a tub design was due to the complexity of the spaceframe. Every point one or more tubes met had to be welded very carefully to prevent undue stress. The welder had to fuse the periphery of every point of contact evenly so as to simulate the "end point loading" which prevented any bending occuring.

  The fruit of Maserati's labours was a car that only weighed 570kg in the original Tipo 60 and 600kg in the most famous birdcage of all, the Tipo 61 (Above). Despite their avant-garde construction and high revving aluminium engines the Birdcages never won at Lemans due to reliability issues, however the Tipo 61 won the Nurburgring 1000km in 1960 and '61.

The Tipo 64 and 65 used an evolved version of the chassis constructed from a greater number of tubes of even smaller diameter. These were nicknamed "Supercages". The Tipo 65 Supercage (Above) was equipped with a 430 bhp 5 litre V8, but it still only weighed 840kg and was reputedly good for 217mph, which in 1965 with contemporary safety systems and no roof must have felt very fast indeed.