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TKART magazine How To | Finding the right setup based on track and grip
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HOW TO... FIND THE RIGHT SETUP BASED ON TRACK AND GRIP

TKART Staff
25 September 2017
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1 TYPE OF TRACK
Karts are known and valued for being simpler than the other vehicles populating the motorsports universe. But this doesn’t mean they don’t offer a variety of possibilities for basic adjustment. While every situation merits an individual assessment to choose the best possible setup, some useful general tips can still be given, starting with evaluating the type of track you’re dealing with and the grip it offers.
The first observations to make, therefore, regard the track’s characteristics: even beginners know that a more technical track, with a series of curves demanding lower speeds, requires a vehicle that’s reactive, agile and equipped with excellent traction to exit curves rapidly. On the other hand, a track with fast curves and long straightaways will be handled best by a vehicle that’s stable, less agitated and capable of greater top speeds.
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The track’s characteristics are vital in the initial assessment of the setup you’ll want to use
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Zuera: one of international karting’s fastest circuits
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PF International: a varied track containing several, not overly long straightaways, but also 90° bends and curves
2 SLOW TRACK
If you’re facing a slow track, then, kart setup should look to enhance reactivity and readiness. So a first piece of advice could be to start with a wider front track width so as to give the kart more precise steering. Keeping our focus up front, you can increase the caster angle and mount the stabilizer bar. The effect of the latter will increase the closer it’s located to the junction of the type-C axle carriers.
Important as well is the convergence which, on a slow track, tends to be “open,” or set on positive values, with the intent of better preparing the kart to receive the driver’s steering input.
As far as the rear axle is concerned, it’s best to set a narrower track width to make the kart faster when turning into curves and give it greater traction when exiting.
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The caster angle is the displacement between the axis of rotation of the axle and a vertical plane passing through the steering axis. If the track is slow, better to increase it.
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The convergence is the angle that the tire axis forms with the longitudinal axis of the vehicle when seen from above. Circuits with many curves favour an “open” convergence
3 GEAR RATIO
Of fundamental importance is the choice of gear ratio (the ratio of teeth on the gear wheel to teeth on the sprocket). If the track is slow and thus lacking in long straightaways, the tendency will be to use a larger gear wheel, coupled with a sprocket with fewer teeth: this guarantees a faster acceleration to the detriment, however, of its top speed.
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In choosing the gear ratio, remember that modifying a sprocket tooth has a far greater effect than modifying a gear-wheel tooth.
4 FAST TRACK
It stands to reason that, in the case of a fast track, the indications go in the opposite direction with respect to the previous comments. Therefore: in front the tendency will be to close the convergence and reduce the caster angle, to obtain a kart that’s less jerky and more precise. The aim is to have it drive as cleanly as possible, especially in high-speed curves where even small steering corrections weigh heavily on the final lap time.
The gear ratios will be longer, but careful not to reach the rev limiter before the longest straightaway is finished.
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Long straightaways suggest a more closed convergence and reduced caster angle
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Long straightaways suggest a more closed convergence and reduced caster angle
5 REAR AXLE
At the rear, a wider track width guarantees a more stable rear axle, especially when turning into a curve. But you need to keep in mind that increasing track width also means greater axle flexibility, and this influences steering control upon exiting a curve, given that only the inner part of the tire will be in contact with the asphalt. This situation can be harmful particularly when exiting a curve that’s immediately followed by a long straightaway. Therefore, you need to evaluate the conformation of the circuit on a case-by-case basis and find the right balance.
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