Total Motorcycle Website – 2005 Ducati 999R Exclusive – Page 5

Cycle parts

Frame and two-member swing arm

There have been no substantial modifications to the frame used on the previous 999R, which is still of the trestle type, constructed in high strength steel tubing. The suspended engine is a bearing component and contributes to the torsional rigidity of the assembly. The cross-member supporting the starter motor on the series production bike is removable to enable use of a larger capacity fuel tank, as provided by the championship regulations. The footplates can be moved to two different positions. A great deal of attention has been paid to weight distribution and the location of each single component, which plays a fundamental role in transferring the loads experienced during dynamic riding (braking, acceleration, curves). Indeed, the individual components must be as close together as possible to contain the arms on which the masses act and as a result the momentum generated, so as to ensure highly responsive handling of the motorcycle. This is yet another reason why Ducati has followed the principle of maximum integration in designing the bike, with the aim of achieving a high density of components in a reduced volume.

The swing arm is identical to that of the motorcycle which will be raced in the Superbike championships. The fulcrum support is an aluminium casting, while each arm is composed of two sheet profiles pressed and welded together to achieve a box cross-section. The left hand member also includes a lower reinforcing member. The wheel shaft is supported by two forged units welded to the ends of the arms. These components are equipped with a failure screw specified to a specific breaking strain which thus ensures that the wheelbase cannot be lengthened under stress. The wheelbase is the same as that of the 999 and the distance between the wheel centre and swing arm fulcrum is 490 mm +/- 12.5 mm (the variability is enabled by the chain tensioning slot). If the failure screw is removed and the rear wheel is set to its furthest back position, the swing arm centre distance is 512.5 mm. In this case the motorcycle’s wheelbase is such as to counteract sudden variations in position during dynamic braking and acceleration (thus reducing rear wheel grip failure under braking and counteracting front wheel lift under acceleration while guaranteeing sufficient drive).

Forged aluminium alloy wheels

The rear and front wheel rims are made of forged aluminium, a technology which enables weight reduction while maintaining resistance to mechanical stress. Compared to castings, it is possible to use thinner sections since the material is distributed evenly throughout the component. The lower weight of the rims not only reduces the suspended masses (which significantly improves suspension performance), but also greatly reduces the gyroscope effect and improves the handling of the bike at high speeds (the bike is more agile when entering curves). Forging is done with a hydraulic press using special dies with a load of thousands of tons. The material thus becomes plastic while maintaining its original molecular structure and hence guaranteeing the mechanical properties of the finished part, even with greatly reduced sections. Casting, on the other hand, requires the metal to be liquid, which alters its molecular structure, and the material is poured into a mould for cooling. There is thus no certainty that the material perfectly fills all the mould cavities. To ensure that the mechanical strength of the part is adequate, castings must therefore be thicker and heavier than forged parts.

The front forks and the new rear shock absorber

The callipers of the front brakes are radially mounted to special mounts on a new Öhlins fork, the legs of which are surfaced in TiN for improved sliding. The two legs have modified, smaller diameter springs and the spring guide is now in plastic rather than metal. This reduces the formation of detritus which tends to pollute the oil. The lower section of the cartridge rod is fitted with a counterspring, which counteracts the main spring at maximum extension during violent acceleration. The usual cam system allows the steering head angle to be adjusted and thus also the trail (91 – 97 mm). The rear shock absorber has been improved by making rebound damper adjustment completely independent (with a one-way valve), so that the rebound damper no longer acts on the compression damper.

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