The current range of Rally Cars being used around the world are very, very sophisticated machines. They have extensive electronics controlling every aspect of the cars performance, and the very nature of the environment that they run in means that the realm of variation can often exceed that of Formula 1. Rally cars jump through the air, are subject to rocks, stones, dust and gravel and are used inside forests, and not on a constant sealed surface. Everything in a World Rally Car is special. A current WRC car can be worth over AUS $1,000,000 when purchased new, and that is just for the car. A spares package, Service Crew, WRC tyres and a truck to operate the car from are all extra.

World Rally Car Components

World Rally Cars (WRC Cars) feature many sophisticated systems that make the car strong, reliable, and easy to drive fast, which is all that is important in today’s competition. The cars vary in terms of the final specification, although the following will generally apply:

Body Shell

The body itself has to remain as the steel unit that the manufacturer builds, although it is totally stripped, lightened by removing unnecessary brackets, seam welded along all every structural joints, and sometimes acid-dipped to thin the metal in non-structural areas. A very light and extremely strong internal roll cage is welded into the body shell.

Seats, Harnesses, Dash and Fittings

All internal components are manufactured from the lightest materials, generally carbon fiber, or another composite material. Every part is required to be as small as possible to keep the weight down, and the concept is to place all the weight as low as possible in the body shell.

Engine

Every engine is individually hand built from specialist lightweight components. The engine is "blueprinted" and features the most advanced materials available today. It is designed to generate maximum torque for the length of one rally event only, including some testing kilometers. A WRC engine could well be worth around AUD $ 165,000.

Transmission

Almost all WRC transmissions are now Sequential, which means that they have a Dog-Box featuring straight- cut gears which are very strong. The selection is done "sequentially" via an electronic or hydraulic mechanism that shifts the gears up or down one gear at a time as a button or lever is activated. The button or lever can be on the steering wheel, or close to it. This allows the Driver to keep his of her foot flat on the throttle pedal during this process, which creates smooth and unbroken power delivery that is similar to a Formula 1 gearshift style. A transmission system could well cost you AUD $220,000.

Differentials

The latest WRC cars have 3 differentials within the Four Wheel Drive System. They have a Front, Centre and Rear differential, and depending upon the build year of the Rally Car, may have active electronic/hydraulic differentials, or plate-type limited slip differentials. The 2 types are described in the following :

Active Differentials

Active Differentials are the most sophisticated form of differential control, as they allow the driver to control the drive to each wheel on the car, both under acceleration, and also braking. This is done by electronically adjusting the plate tension inside each differential, which is eventually controlled by hydraulic oil pressure. This allows a driver to adjust the drive percentage from front to back, and also to tighten or loosen the front and rear differential settings.

Limited Slip Differentials

These units are simpler than the active systems and provide similar characteristics to the active units albeit without the adjustability whilst moving. Therefore, each unit must be built, adjusted, installed and tested in the car to see how it performs, before being removed, reset, refitted and re-tested. The cost factor is however somewhat reduced.

Brakes

WRC cars have very large brake rotors and calipers, which are designed to allow the driver to move weight around in the car as quickly and efficiently as possible, whilst also being able to slow the car very efficiently when needed. The systems used generally feature aluminum brake calipers, that typically have 4, 6, or more pistons at the front, and 2 or 4 pistons at the rear. A pedal box allows incremental adjustment of bias between the front and rear brakes, and is adjustable whilst moving, thus allowing the driver to achieve perfect brake balance for any surface.

The handbrake is usually an upright lever located close to the steering wheel, and allows negotiation of very tight turns, or "Handbrake turns". When it is used, it automatically disengages the drive to the front wheels, by opening up the Centre Differential to a "No drive" setting to the front, which then directs all the power to the rear wheels, until the lever is released. This allows the driver to execute a perfect " Handbrake turn ", as the rear of the car comes around in a huge 300 bhp power slide. The braking system on a Rally Car needs to be operating perfectly, as a large part of the driver’s confidence revolves around having a great feel in the brake pedal along with highly efficient action.

Suspension

This is the area that has been responsible for the greatest changes in car speed in recent years, The WRC systems are built by Reiger, Ohlins, Proflex and Bilstein, and are all very sophisticated. Each unit acts totally independently, and most operate "upside down", where the actual damper unit is inside a very large ( 50-60 mm in diameter) cylindrical case, that slides up and down inside another cylinder outer casing, which could well be constructed from titanium. This contains needle roller bearings for the top and bottom bushes, to eliminate friction. Each unit is incrementally adjustable, sometimes with 30 adjustments for compression (pressing down) and as many as 20 adjustments for rebound (lifting up). Coupled with this, 2 or 3 different speeds of adjustment are also catered for. This means that a unit can have High Speed Bump, Medium, and Slow settings for each of the aforementioned adjustments. Hours of fun! Each unit can be AUS $10,000 or more to purchase, and the selection of suspension system is critical when building a Rally Car.