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TKART magazine Track Test Tech | TM KZ-R1seamless gearbox by Machac Motors

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SEAMLESS VS. TRADITIONAL SEQUENTIAL: COMPARISON TEST OF THE TWO TRANSMISSIONS FOR SHIFTER KART ENGINES

Giacomo Mantovani
21 October 2023 • 14 min. read

We compared the performance of an TM KZ-R1 engine equipped with a traditional gearbox and that of the same engine, but equipped with the S1087, the transmission (analysed in the article "Technical Focus - S1087 by D.M.A. Racing Gears, The first seamless gearbox for Shifter karts") without torque variations that allows you to change gear "keeping the acceleration down". According to D.M.A. Racing Gears (the manufacturer that produced and patented the transmission) this solution allows a gain, in terms of lap time, ranging from 2 to 5 tenths. Will our test confirm this? 

test in points
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To verify, with the same preparation of the Shifter engine (a TM KZ-R1) and track grip conditions, what the differences are, in terms of performance and driving sensations, between the use of a traditional sequential gearbox for karts and the seamless transmission by D.M.A. Racing Gears. 

We examined the trend of the engine rpm in the sections of the track considered, the speeds reached and the driving sensations. 

Comparisons were made regarding:

  • Fast track sections
  • Mixed track sections
  • Start

Steel Ring track - Trīnec (Moravia-Silesia) - Czech Republic. The circuit has a total length of 1,234 m, a width of about 9 m (7 m total elevation gain) and has 8 left-handers and 10 right-handers.

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We were able to count on a well-kept and regular asphalt, even if the surface, in general, had little grip, although our tests were carried out only 24 hours after the second round of the OK and OKJ FIA Karting European Championship. The test was carried out from 12 pm to 4.30 pm, with a TM KZ-R1 engine and VEGA XM3 CIK PRIME tyres. 

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IN THEORY
HIGH GEARS / LOW GEARS

Of course, not all gears are the same. As a result, gear changes are not either. Changing gears at the highest speeds is generally the easiest, regardless of the type of transmission (traditional sequential or seamless). In fact, in this condition the "gearbox-wheel" unit has a high speed and allows the consecutive gears to have more similar rotation speeds, an aspect that facilitates the possibility of shifting into gear. Moreover, although experienced drivers do not encounter great differences in this sense, it is objective that gear changes at high speeds allow a lower loss, in terms of lap time, than in gear changes at low speeds. When the kart is launched at high speed (despite having to deal with greater aerodynamic resistance, to learn more about this read "Technique |  The aerodynamics of a kart"), the stopping in the increase in speed, in conjunction with the "detachment" of the throttle, is in a lower percentage than what happens at lower speeds. In low-speed gear changes (when you go from 1st to 4th, for example) other factors come into play that contribute to making this type of shift more "expensive" in terms of lap time, such as demanding acceleration, tight corner radii and sudden changes of direction. This is precisely why the coordination necessary for a driver when changing gears, between 1st and 4th gears, greatly affects final performance.

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