The 813 started life as a Len Bailey design for a F1 Theodore that never saw the light of day. Automotive Designs took the whole thing over in mid 1980, modified the car for F3 and produced the first chassis in autumn of the same year.
The chassis featured a narrow tub for maximum sidepod width, suspension was inboard with the rear spring/dampers sitting over the gearbox. The fuel was housed between the driver and engine and Toyota-power was used.
The 823 was a reworked version of the 813 and initially results were disappointing but a lot of work saw it improving a David Leslie took a sixth place at Silverstone at the end of June. Later in the year an understandably frustrated Leslie left to drive a Ralt RT3 which stopped any further progress.
The 853 was a new design for the new flat-bottomed regulations and it used a logical development of the tub of the previous year’s 843. The chassis used aluminium sheets over honeycomb bulkheads to give a combination of strength and rigidity. At the rear there was a tubular steel frame that acted as an engine bay. The front suspension employed pushrods to operate the inboard springs and Koni dampers. At the rear rockers, hanging from sandwich plates, operate the dampers which were installed on top of the gearbox, lower wishbones take care of the bottom location. Magnesium uprights were fitted all round, also made of magnesium was the steering rack. The fuel and oil tanks sit between the driver and engine with an oil cooler in the left hand sidepod.
Unfortunately the two Finns who drove the cars early season weren’t very good and their frequent offs soon exhausted their budgets. Paul Jackson carried out a lot of mid-season testing which made a big difference and at the end of the year Cor Euser took pole and fourth place at Zandvoort showing what might have been.
The 863 looked very different to the 853 but it was still considered to be an evolutionary design. Now the chassis was composed of an aluminium honeycomb with four cast magnesium bulkheads in the footwell and the dash area which was claimed to give a “massive increase in torsional rigidity” as well as increased driver safety. Pushrod suspension was fitted front and rear operating Koni gas-filled dampers. The bodywork and rear wing were totally redesigned to give the highest levels of downforce with the flat bottom now fitted.
The engine/rear suspension of the 873.
The 873 rear wing and diffuser.
Yet another evolutionary design, the major change was a switch to a Staffs Silent Gear gearbox in the interests of increased torsional rigidity, reduced friction and more compact size. The dampers were now located either side of the gearbox instead of on top to allow a flatter engine cover to be fitted. Newly fabricated uprights and revised rear suspension were also employed. A narrower nose was fitted to increase the front wing area. The whole car was reckoned to be 20kgs lighter than the 863.
Despite all the work that went into the new design the 873 never appeared at the races.