When examining the transmission and drive trains of the Focus WRC it becomes obvious that Ford learned a lot from its competitors.  As mentioned earlier the Focus uses a transversally mounted engine. The gear box however is installed longitudinally just like in the Peugeot 206 WRC. This layout necessitates very complex gearing and shafts in order to allow the transmission of torque to all the wheels. There are mainly two reason behind this choice. The first is the necessity to be able to change a gear box in less than 20 minutes, the time during which the World Rally Championship cars are allowed to be serviced. If the box was mounted transversally then the front-left suspension would have to be removed before being able to change the box and the procedure would be much more time consuming. The second reason is that by mounting the gearbox longitudinally the car has a better weight distribution by centering masses inside its wheelbase. In the Ford Focus WRC the weight distribution is 52% on the front wheels and 48% on the rear ones, almost perfect. The gearbox of the Focus WRC is pictured below.

The Ford Focus WRC gearbox

As you can see in the picture above engine torque is picked up at the transfer box, on the right part of the picture, and then distributed to the front wheels through shafts (not shown) in the middle of the box and the rear wheels through the part on the left of the picture. The Focus gear box was developed by XTrac the British gearing specialists and it is of sequential type (i.e. non H-pattern based). Gear changes are operated through a joystick located close to the steering wheel just like in the Toyota Corolla WRC. I am unsure whether the joystick is actuating electronics or mechanical parts. As soon as I find out I'll let you know.

A frequently neglected part of a rally car is its aerodynamics. Only recently have these cars undergone extensive developments in this field. It's true that very rarely rally cars reach speeds in excess of 200Km/h. There are however constraints that should not be neglected such as engine compartment air circulation and hot air evacuation, brake system air ducting etc. In this field the Focus excels. The base car has an aerodynamic drag coefficient (a.k.a. Cx) of only 0.32 which was raised in the WRC car (mainly due to greater heat produced by the engine) to 0.36. The Focus is so well designed that there's almost no need to provide additional down force hence the absence of spoilers.

Like all other major contenders in the WRC, Ford equipped their car with active, hydro-electronically controlled differentials. Already in its first incarnation the Focus was holding three of these devices, one for each axle. The team had to revert to a front and center active differential quite quickly and use a classic mechanical differential at the rear. It is extremely complex to fine-tune a car using three active differentials and, if not perfectly well adjusted, there is no real gain in using active differentials all around especially on slippery surfaces. It is expected that the Ford team will introduce cars using three active differentials at the New Zealand 2000 rally.

Active differentials are usually composed of a classic, free (i.e. non self-locking) device which holds what can be described as a clutch. The clutch progressively operates the differential's locking and is commanded by electronics and sensors and activated by hydraulic pumps or electric current. The locking characteristics of these differentials vary not only depending on the terrain and its skidding nature but also according to predefined settings that the driver or engineer can set at will, in-car and in real time. For instance the driver can fully lock all differentials at the start line of a special stage in order to favor acceleration and release them immediately afterwards. Hydro-electronic differentials have many advantages over their mechanical counterparts and in particular the ability to act within extremely short time delays (less than 1/10th of a second) as well as to be able to vary their locking abilities continuously, depending on many more parameters than mechanical differentials. Downsides include their price of course, the additional weight of the hydraulic pumps and circuitry and the lack of reliability they introduce when compared to mechanical differentials.

Overall the Ford Focus WRC is well in line with what's going on in other major company entries in the WRC. After a period of testing and development (the car had only lived for 11 months in January 1999) it will surely be able to at least keep up with its main rivals.

Next