RALLY: Ford Focus Rally Car Will Set New Standards
4 January 1999
Courtesy Ford Motorsports
- 'No compromise' rally car design starts with clean sheet of paper
- Design builds on attributes of Ford Focus road car
- Zetec E engine with bespoke turbocharger optimised for fast
response
- Longitudinal six-speed sequential gearbox for optimum weight
distribution
- Four-wheel drive with three active differentials. Rear differential
is particularly compact for increased ground clearance
- Compact wheelbase in class provides stability and allows key
components to be located in the middle of the car. e.g.
- Fuel tank mounted amidship for optimum weight
distribution
- 52:48 weight distribution becomes 50:50 downforce from the
rear wing at speed
- Engine moved back 20mm and tilted backwards at an angle of 25
degrees
- Long travel strut suspension with new low friction wheel
bearings
- 30 per cent stiffer shell than Ford Escort World Rally Car
- Extensive use of lightweight materials, eg titanium pedals, steering rack and hubs
- Fuel tank mounted amidship for optimum weight
distribution
The Ford Focus rally car, like the road car, is all-new, sharing few parts with the Ford Escort which won more rallies than any other competition vehicle over the past 30 years. The Ford World Rally Team designers - led by project manager Guenther Steiner - worked closely with the Ford Focus team from the Small and Medium Vehicle Centre at Dunton, Essex and Cologne, Germany to ensure unparalleled access to Ford's technology and resources.
The Focus WRC is powered by a specially developed version of the 4-cylinder 2-litre Ford Zetec E engine fitted with a purpose-built Garrett turbocharger. The engine generates 300 bhp at 6,500 rpm. The maximum power output is controlled by the mandatory 34mm air intake restrictor required by rally regulations and the engine and turbocharger have been developed from the outset with the restrictor as one of the design parameters.
Ford engineers concentrated on producing a highly responsive power unit that gave generous levels of torque for maximum driveability and pulling power. With 550 Nm at 4,000 rpm, the Zetec E engine has 10 percent more torque than the Escort WRC and a significant proportion of this torque is available from just 3,000 revs.
The engine is mounted transversely, as in the Focus road car, but is lowered and moved back by approximately 20 mm, as permitted by FIA regulations. It is fitted with a special transfer case to turn the output drive through 90 degrees to mate the engine to an all-new six-speed sequential gearbox which is mounted longitudinally behind and below the engine. This layout puts the weight of the transmission low down, at the centre-line of the car and moves it back within the bodyshell. It also allows the engine to be tilted back by 25 degrees to further optimise weight distribution.
Via the six-speed gearbox, power and torque are distributed through hydraulically-controlled 'active' differentials located at the front, centre and rear of the car to all four wheels. The all-new rear differential is exceptionally compact and helps to create unusually good ground clearance which is important for rough gravel events like the Acropolis and Safari rallies.
The bodyshell of the Focus WRC builds on the fundamental attributes of the Ford Focus road car which is both aerodynamically very efficient, inherently stiff and packs the majority of components within the wheelbase to optimise weight distribution. Extensive use is made of carbon fibre and titanium to obtain maximum strength with minimum weight.
Based on the three-door Focus, the left-hand drive World Rally Car retains both the exterior and interior appearance of the road car. The body shape closely resembles the original, but with larger air intakes in the nose to feed the bigger water radiator and intercooler for the turbocharger. The wheel arches are flared to accommodate larger wheels and tyres and the rear wing sits neatly atop the rear window.
The rear wing is of modest proportions as the amount of downforce required to balance the car at high speed is not great. The Focus WRC has a 52 per cent front / 48 per cent rear weight distribution, due in part to the location of the fuel tank. Unusually for a four-wheel drive rally car, the 100-litre safety fuel tank is housed in the same place as the road car - under the bodyshell, below where the rear seats are in the standard car, and ahead of the rear axle. A ballistic carbon-composite undertray protects the tank from the rigours of rallying.
The Focus road car is 15 per cent stiffer than its competitors so the Focus WRC requires less strengthening material than previous rally cars. Crew safety remains of paramount importance and the rally car is fitted with a computer designed, purpose-built roll cage constructed from 45 metres of steel tubing. The door cavities are packed with a carbon and aluminium honeycomb filler, covered by special interior door trims moulded in carbon fibre to the original road car design.
Other elements of the interior also echo the road car. The ergonomics of the Focus cockpit were studied and found to be so good that the interior of the rally car effectively replicates the original design - but using hand-made carbon fibre materials and housing the mass of specialist switch gear and equipment required by a rally crew. One of the few items to change significantly from the road car is the gear lever for the sequential gearbox. This protrudes from the dashboard to place the lever close to the driver's right hand. The driver simply pushes to change up, and pulls to change down. The system is designed to reduce 'hands-off-the-wheel' time to the minimum.
The stiff bodyshell provides an excellent foundation for a fully independent suspension system. This uses fully adjustable MacPherson struts front and rear, is designed to give long wheel travel for good traction and features interchangeable components to reduce the number of spares carried on events and ease the task of servicing. New ultra-low friction wheel bearings are fitted, specially developed for the Focus WRC.
For asphalt rallies the Focus will run on 18 inch diameter OZ wheels, with narrower, smaller diameter 15 inch wheels for gravel events. For every event, the wheels are shod with low-profile Michelin tyres. The braking system features Brembo ventilated disc brakes, with mono-block 8-pot calipers at the front and 4-pot at the rear, for asphalt events. The balance of braking effort front-to-rear can be adjusted from the cockpit.