Bodywork – AUDI QUATTRO RALLY CAR MANUAL

Bodywork, chassis and aerodynamics

The bodyshell of every Audi Quattro for competition use was built by the specialists at Matter, who went through the production line article with a fine-toothed comb and hand-crafted each example with the lessons learnt from previous testing and competition experience.

Effectively, every car from Matter was a hand-built original, including the fully integrated roll cage, and each new shell was given a stamp bearing its production number; R1 being the first prototype rally car. By the end of 1983 more than 50 cars had been built and the numbers kept rising in the development of the heavily modified Audi Sport quattro in both standard and aerodynamically enhanced S1 configurations.

With the Group 4 cars, the major preoccupation initially was in reducing the Quattro’s hefty bulk. A regular rear-wheel drive

Group 4 car like a Ford Escort RS1800 would tip the scales at little more than 900kg (1,984lb), whereas on its debut at the 1981 Monte Carlo Rally the fully laden Quattros weighed 1,240kg (2,734lb).

Almost immediately, the job of the historian (not to mention that of subsequent owners and vendors seeking provenance) became rather complicated. For example, in Portugal 1981, the third event of the Quattro’s rally career, the results of Matter’s use of thinner gauge steel gave a stated weight of 1,040kg (2,293lb) for Michele Mouton’s newly built gravel car, compared to 1,080kg (2,3811b) for Hannu Mikkola’s example.

Yet the registration plate on Mouton’s car was IN-NV 90, which had been carried by Mikkola on his victorious solo outing in Sweden three weeks earlier – the same car that won the Janner Rallye as the Quattro’s first victory (using a different engine). It would not be the last time that such a phenomenon occurred.

From early in the programme, Matter and Audi Sport were able to tailor the build of each shell to the demands of the event that it was to compete in – just the same as any other component like the tyres. At one end of the scale were cars intended for the Tour de Corse, which must be as light as possible for turning in to and powering out of the hairpins. A standard shell would suit Monte Carlo or Sanremo and then the weight would go upwards depending on how much reinforcement was needed.

The most durable and heavyweight cars seventh appearance of the Quattros in world championship trim, the 1981 Sanremo Rallye, saw Audi Sport arrive with a very different structure in place, the result of extensive work by Gumpert and homologation engineer Jurgen Bertl to kill several birds with one stone.

The enlarged wing effectively created a frame inside which the oil cooler was housed, allowing a free flow of air at all times to help stem the tide of engine-related retirements. In addition to enhanced cooling, moving the oil cooler outdoors also removed a weighty item from the nose of the car and helped in its modest way in addressing the main problem of the Quattro’s design – its nose-heavy weight distribution.

Ferdinand Piech’s five-cylinder engine was a lusty gem but its installation was troublesome. It sat longitudinally in front of the front axle in a crowded engine bay, giving the Quattro a 60/40 weight distribution, which dulled its turn-in and provoked occasionally epic understeer behaviour. Pulling weight rearwards was a huge preoccupation throughout the Quattro’s competition life, and although the absence of the oil coolers helped, the space that it left was soon filled by enlarged turbos and intercoolers.

For 1983, Audi Sport had to produce its cars to Group B specification, and this presented Matter with a whole raft of changes to consider. Firstly, the construction of the cars was virtually free, allowing for the introduction of exotic, lightweight composites in fabricating the body panels. As early as the 1982 Swedish Rally, the boot lid was made from Kevlar. Soon this would become the primary material used in the body.

The interim Audi Quattro A1 had new Kevlar wings hung on each corner, filling the maximum permitted body width and able to house the widest possible asphalt tyres without the need for eyebrow extensions. A vent cut into the rear arches assisted in cooling the rear brakes, with more vents appearing in the nose of the car, on which the bonnet was made from what was then termed ‘space-age carbon fibre’.

Reducing the sheet metal to a minimum at the front required Matter to completely redesign the front impact structure. A robust spaceframe was created that was then dressed in the composite panels, into which the engine and transmission would later be fitted. When fully prepared for a rally, the quoted weight given for the A1 was 1,130kg (2,491 lb), which may sound like an anathema when the Quattro was 1,080 but the A1 was classed as an ‘over 3-litre’ car once its turbo was taken into account, which meant a minimum weight of 1,100kg (2,425lb). All that would change with the arrival of the next car.

Within four months, the Audi Quattro A1 was superseded in front-line service by the Audi Quattro A2. The A2 had a fractionally smaller engine and thus dropped into the lower capacity class of ‘up to 3 litres’ with a reduced minimum weight of 960kg (2,1161b). On their debut at the 1983 Tour de Corse, using titanium for the roll cage, the Quattro A2s were quoted as weighing ‘just under 1,000 kilograms’.

The easiest way to tell the A2 apart from the A1 was that the later car had a more pronounced flare to its rear wheel arches, beginning much further forward along the sill and giving a much more muscular look to its haunches. Not only that, but the A2 had a second vent cut in above the first, through which air was channelled to cool the rear differential.

For the Group B era, Audi replaced alloy panels with weight-saving Kevlar and carbon fibre.

Many revisions would be made to the A1 and A2 in the course of a competition career that lasted right up to the end of Group B rallying, both in the hands of the works team and its private customers. Among these was a slight rise in the floorpan from front to rear of the cars built after the start of 1984, intended to coax weight distribution backwards along the longitudinal axis and resulting in what Hannu Mikkola and Stig Blomqvist agreed were the best-handling Quattros of all.

There was to be no such fiddling with the details for the next step in the Quattro’s evolution, however. In September 1983, Audi showed off a new concept car at the Frankfurt Motor Show that it called the Audi Sport quattro. This rather dramatic-looking vehicle was a Matter-crafted road car upon which the most obvious change was a dramatic shortening of the wheelbase from 2,524mm on the standard road cars, Group 4 and Group B cars to just 2,204mm on the new model.

Radical surgery had been needed – the cut coming from between the B-pillar and rear wheel arch – to produce a rather caricatured quattro, from which the capital ‘Q’ had also been shorn. Most observers were so flabbergasted by this dwarfish creation, not to mention the fact that it had four valves per cylinder, that they failed to notice that the windscreen was mounted at a considerably steeper angle.

The rationale behind the car came entirely from the rally team. As early as 1981, the Audi Sport engineers had been investigating ways in which to make their cars more competitive on asphalt, particularly the tortuous roads of Corsica upon which they were always at a disadvantage. While they were discussing all of the various modifications, Hannu Mikkola chimed in to suggest that the original Quattro’s rakish windscreen was very stylish but did cause some issues with visibility due to reflecting the sunlight badly.

The simplest solution was therefore to take the more upright windscreen and A-pillars, together with the scuttle, firewall and other accoutrements, from the standard Audi 80 saloon and graft them on to the truncated quattro pan. The public response to the ‘concept car’ in Frankfurt was overwhelmingly positive, and as a result Audi signed off on a limited production run of 200 cars, each to be hand-built by Matter and Audi Sport, that would go on sale direct from the factory at the staggering price of DM200,000 (or £50,000/$75,000 in 1983), which was double that of the standard Quattro.

Of course, 200 units was the requirement for homologating the new car for competition, and thus the Audi Sport quattro became the preferred choice of the rally team management from the 1984 Tour de Corse onwards. The problem was that, as far as the majority of their drivers were concerned, they were much better off with the old cars.

Shortening the wheelbase of the Quattro had the rather unfortunate side-effect of undoing all the good work on weight distribution. When it went into competition, a thumping 63% of the car’s weight was sat on (or beyond) the front axle, with just 37% left to hold the back end down. In total, the quote weight for the Audi Sport quattro was 960kg (2,1161b) on its debut in Corsica, although in truth it was around the 1,200kg (2,6461b) mark.

The shortened car was incredibly nervous by nature, which proved rather a trial for its occupants. Besides its quirky weight distribution, Audi chopped the air dam of the car beneath the integral radiator and bumper, extending the composite sump guard upwards to meet it like a clam shell. The result was that the Audi’s nose would be pushed upwards by the airflow, which relieved the drivers of any remaining sense of control that they may have entertained. Mikkola and Blomqvist lobbied hard to have their Quattro A2s returned.

In hindsight it was probably fortunate that the Audi Sport quattro debuted on the same weekend as the car that was to define Group B: the Peugeot 205 T16. The deficit between the Sport quattro and the Peugeot was as large as that of the rear-wheel drive Escorts and Talbots had faced against the early Audis – which meant that development had to happen swiftly.

The first response in Ingolstadt was to throw more power at the wheels, but the

shortcomings in the car’s handling would preclude going too far. Instead the whole car was re-engineered with as many of the ancillaries as possible being taken out of the engine bay and put in the boot. The radiator with its attendant fans, together with the alternator, were thrown to the rear extremities, the oil cooler relocated and the centre of the car required to accommodate roughly 10kg (2211b) of additional piping and wiring.

Its bodywork would also need to be redesigned with a raft of appendages to regain control of the little beast – resulting in the dramatic-looking Audi Sport quattro S1.

Audi Sport’s engineers went to dramatic lengths to use the air to push the car down. A vast rear wing was mounted on the boot and a snowplough front wing was wrapped around the bodywork, from which long strakes reached back over the extended front wheel arches to channel the air down the sides of the car in tandem with extended door sills.

Roland Gumpert claimed that the downforce generated by the new bodywork was the equivalent of 500kg (1,1021b) – with the advantage that those 500 kilos weren’t physically present. The new car would have looked very composed, were it not for the extra 100+ bhp under its bonnet.

The wheelbase was also increased by 20mm compared to the Sport quattro. In this final iteration, Audi got the weight balance at 52% on the front axle and 48% at the rear, with the total weight being claimed to be 1,100kg (2,425lb).

This would be the ultimate iteration of the Quattro in all its rally forms. A mid-engined prototype was assembled – in fact four of them – after design work was commenced in mid-1984. At first this work was spoken of openly but as official disapproval mounted, the project was moved out of the Ingolstadt factory and into a corner of the Neckarsulm plant. The mid-engine prototype was not tested until the autumn of 1986 when it was sent to Czechoslovakia for Walter Rohrl to assess.

When the FIA announced that the 1.2-litre turbocharged Group S would be phased in through 1987-88, Audi decided that its future lay elsewhere and Ferdinand Piech demanded a halt to all activity. The three cars that were built officially were crushed under Piech’s supervision but the fourth survived and now resides with Audi Tradition with the full 2.1 -litre Group B engine and the concept car bodywork rather than the truncated Sport quattro shape that it ran in 1986.

The Sport quattro S1 had one last mutation, however, for Walter Rohrl’s all-out assault on the Pikes Peak International Hill Climb of 1987.

All remaining traces of the road car shell were removed from this one-off vehicle in favour of a purpose-built spaceframe dressed in Kevlar panels, with which a 50/50 front-to-rear weight split was finally achieved. The original panels were taken from the S1 with which Bobby Unser had won the 1986 event, and to the naked eye it was a near-identical car with a few additional NACA ducts. So ended the line of the original Audi Quattro.

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