Maximising traction on KZ karts: a track engineer explains how

INTRODUCTION

When we talk about traction, we are referring to the kart’s ability to accelerate starting from the centre/exitphase of a bend, when the driver steps on the accelerator pedal again. Maximising traction, thereby reducing rear tyre spin, is essential to ensure the best possible approach to the next stretch of track and, perhaps, be able to get alongside whoever is in front and overtake them. It is not uncommon to see a driver get close to the kart in front on bends, but not to be able to complete the overtaking manoeuvre because they are unable to exploit the full power of the engine when exiting the bend.

Traction is essential in the exit phase of a bend, in order to be as quick as possible down the next straight

1 WHY IT IS IMPORTANT

KZ karts, equipped with 6 gears, are able to fully exploit the maximum power of the engine compared to non-shifters, because they make the engine work in a narrower range of engine speed (rpm) by choosing the gear according to the kart’s speed. That’s why, on KZ-engined vehicles, there is often a greater risk of wheel spin when accelerating once more, given the excessive power compared to the grip provided by the tyres. To avoid having to sacrifice this power, you need to try to improve the grip that the rear tyres exert on the ground during this phase as much as possible.

A non-shifter kart uses a much greater range of rpm range (red curve) compared to a shifter kart (black curve). Therefore, even with the same engine power curve, a shifter kart is able to develop more power on exiting a bend, since it can make the engine work closer to around its maximum power

2 PROBLEMS

There can be various causes for loss of traction: poor grip provided by the track (for example, a dirty track or, even worse, a wet one); a tyre that doesn’t perform at its best due to the set-up not being perfect; a driver’s incorrect driving style. While not much can be done in the first case, with regard to the other two, a bit of useful advice can improve things.

Loss of grip due to excessive power at the rear wheels can result in so-called "power oversteer"

TRICKS FOR... MAXIMISING TRACTION ON KZ KARTS