Here's an interesting article on how the Gipsy was constructed.
This photo courtesy of BMC-Leyland Heritage Group Inc
The Austin Gipsy 1958-1968
The Austin Gipsy was announced on February 28th, 1958. It was intended as a civilian replacement for the military Austin Champ and a commercial rival to the Land Rover. It was the first vehicle to be produced with independent trailing arm rubber suspension on all four wheels.
The Gipsy was designed as a rugged cross country machine. It had a steel rounded box section chassis with a wheelbase of 90 inches and an all steel body. It was powered by the 2199 cc four cylinder petrol engine made famous by the Austin A70. This had a good reputation for reliability and was probably one of Austin's most successful engines having been originally designed just before the war and remaining in use in various forms, right into the 1970's. There was also an alternative 55 bhp diesel engine of 2178 cc which also had a good reputation, becoming the standard power unit of the famous London taxi. There was a robust four speed gear box with synchromesh on the second, third and fourth gears and a transfer box giving the operator the choice of either rear wheel drive high, neutral for pto or four wheel drive in low ratio, later the G2 And G4 came with a transfer box that had a choice of 4 wheel high and 4 wheel low. The maximum payload was 10 cwt, and a maximum drawbar pull of 3000 lbs. Perhaps the most unusual feature was the use of Flexitor rubber trailing arm independent suspension units on all four wheels.
Austin had been thinking about a civilian replacement for the Champ and had produced some special bodied models on similar lines to the proposed Gipsy, incorporating opening side doors, a hinged tailboard, lengthwise rear seats and a canvas tilt.
The Champ had proved the usefulness of independent front and rear suspension for fast driving over rough terrain. It was decided that a suspension system giving comparable performance to that of the Champ, but at a reasonable cost for mass production was needed. Several chassis with wishbone suspension systems similar to the Champ were constructed and run experimentally, but production would have been expensive and maintenance requirements would also have been elaborate. It was not until Austin designers had seen a light military trailer equipped with Flexitor rebber trailing units at the Fighting Vehicle and Development Establishment test ground at Bagshot Heath that they decided on a suitable system that offered freedom from lubrication problems and a comparatively low production cost. They were impressed with the way the suspension coped with repeated impacts on the corrugated section and decided to explore its suitability for a four wheeled vehicle.
The patented Flexitor suspension (produced by George Spencer, Moulton and company.) employed a pre compressed rubber cylinder which was chemically bonded to a tubular steel housing and to an axial shaft on the end of which was mounted the trailing arm carrying the wheel. All deflections of the arm resulting from bumps were absorbed by the twisting of the rubber. The units embody a measure of self damping, but hydraulic shock absorbers all round gave extra control. Spring failure was virtually impossible and tests showed that it had a life of over three times greater than that of conventional leaf springs. It was initially intended to have inboard brakes but due to legal requirements this was not possible. This braking system would have been ideally suited to this type of suspension.
The steel body was built as a unit, mounted on the chassis at six points. The sides were formed from sheet steel with box section reinforcement and was roto dipped for protection against rust. There were easily detachable side doors, operated internal cables, at the front and a tailboard supported by chains at the rear bench seats.