MODENAS KR3 – THE FRAME AND THE BODY

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Article By Francesco Lanfranchi

With this article, we start the technical analysis of the bike that made possible the debut of the Modenas-KR Team in the 500cc world championship, in 1997. As we wrote in the first episode, the bike was an incredible ensemble of innovations and state-of-the-art solutions. The frame was a central point of the project because it should compensate the less power of the 3-cylinder engine. The focus was on reaching a superior handling and a narrower front section of the bike.

In order to do this, a deltabox aluminum structure was designed by the partnership between engineers from the KR Team, TWR and FTR, a French chassis manufacturer that also engineered some Moto2 and Moto3 bikes few years ago. The lightness of the engine allowed to use lighter and smaller beams in respect to the Japanese competitors, while the setting possibilities followed the current solutions: eccentric bushings both for swingarm and the steering plate pivots, in order to make possible variatons on caster, trail, and height of the axes.

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The swingarm was in aluminum too and featured a boomerang shape on the right side, in order to keep the muffler straight. The whole structure was incredibily light and narrow but, probably due to the still rough design of the engine, the bike resulted in overweight of about 10 kilos, in respect to the minimum allowed weight (135 kilos). The brakes were provided by Nissin, a partnership that the team will maintain for various years; it’s interesting to note that the brake calipers were still fixed by axial screws, because the radial layout will be adopted only from the early 2000s.

The tires were Michelin, that were becoming more and more performing in respect to the Dunlop; unlucky, the French manufacturer always made distinctions between big and small teams, so the Modenas-KR crew had to use often old-spec tyres, or specs designed for other manufacturers. The ensemble was completed by a super-aerodynamic bodywork designed by Lotus, which maximized the advantage of the bike in terms of aerodynamic resistance. In the 1997 version, it featured two protruding “cannons” for the engine feeding: this design was adopted because a protruding airscope avoids the boundary layer, very slow, that is present on the surface of the bodywork, allowing a bigger flow of air to the engine and, in the end, more power.

I conclude this article mentioning engine and power, because on these arguments we will focus in the next article: we will see that the most relevant part of KR3 innovations was concentrated in this area.

See you on the next episode!


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