How to get ready for the cold - Part 1

With winter upon us, it’s normal to expect cold weather. And for everyone who is exposed to the elements, like kart drivers, the weather is really felt. At this point, you can decide whether to store up your kart or keep on going to the track for a few laps. However, if you can decide to continue using your kart and especially if you want to go back home in one piece, it’s better to do a few jobs on it, technical and non- technical. Let’s take a look at one or two things that you could do.
 
GIVE SETPUP A BIT OF GO
 
If we aren’t lucky enough to find a warm day, almost certainly our kart will start to skid very much more than it usually does. This is due to various reasons: tyres don’t warm up as much as they do in summer, or they take longer to reach the right temperature, and already just for this reason we’d be slower round turns; but when at slower speed it’s more difficult to load tyres to the right point so as they warm up properly. The first “mechanical” tip is to let tyres work harder, loading those more. We can easily see that the first thing to do is work on track (especially rear) so that the centrifugal force round the corner conveys more weight and pressure on the tread. With the same aim, you can increase chassis height from the ground, both at front and rear, and also the seat height. In this basic adjustment you must also consider hubs, mount longer ones that load tyres directly. Watch out though because some chassis and some axles tend to work lessi f they haven’t got sufficient “lever arm” between the wheels and the rear bearings, something that could influence kart behaviour on the track very much. So, if there are problems you could start doing some “experiments”, for example work on the height of the third bearing on the axle and check the reactions you get by locking it and loosening it. This is a rather simple operation and above all, one that allows you to check rapidly which is the best direction to aim for whether to make it stiffer or adapt flexion in the area. You see, we have always to bear in mind that not all chassis react in the same way, and that situations are hardly ever “coherent” and unchanged: at times conditions are such that you get the desired effect doing the exact opposite of what you have always done.
 
LOOKING FOR WARMTH
 
To give you an example of set-up in the antithesis with “golden rules” of the definition, take camber: in normal conditions, with karts (because it works differently with cars), the straighter the wheels, more hold there is: while if we have negative camber, that is, tilted inwards, they tend to skid. The thing is that at times, when it’s cold and temperatures are very low, and the tread rests on the asphalt, tyres are not stressed enough so they won’t warm up. But, if we reduce the area where it touches the ground, increasing camber, the tyre is subject to more load, so it manages to warm up and there is more grip. Obviously there are limits to this, buti t helps us to see how, at times, you must be a bit elastic with “set-up regulations”. And as we’re dealing with the characteristic geometry of the wheels, don’t forget that an adjustment that help both aspects directly (more grip and more heat for tyre) is the toe in. So open the wheels at the front with too much hesitation, even up to 20mm only if necessary (remeber we’re talking about extreme cases, let’s get there but always gradually), because we’d get more directionality and at the same time tyres would warm up quicker. Moreover, being the front ones and threrefore not subject to torque, they usually take a bit longer. In fact, in defining this set-up it’s up to driver’s sesibility (and experience) to feel if less grip depends on adjustment or the fact that tyres haven’t warmed up enough; if we have lack of balance after some laps it could depend on the fact that front tyres reach the right speed after the rear ones. To conclude the topic on steering geometry, usually it’s good to increase caster, that is, spindle pin tilt back: this happens because the minimum lateral road hold tends to let the internal rear wheel lift, with consequent more “nervous” behaviour of our kart as it travels round turns, something that is instead helped by increasing caster angle.  
 
OUGHT WE DO THE PUSH-UPS?
 
Staying on the subject of “wheels”, don’t forget that as consequence, tyre pressure has to be adapted. The reason is that work pressure, the same that the wheel uses to work when we are on the track, depends on how the air inside the wheel heats up (expands). So the warmer a tyre is the more the air expands (a principle of physics) and the tyre pressure increases. To start with, we might just increase pressure by a few points (tenth of a bar) but ideally, you should test wheels when warm and compare that reading with previous redings. Now, you can’t make up the difference all in one go, but at least you can halve it, and anyway this enables us to understand the level we are at and what needs to be done. Always bear in mind that in this case too, it’s possible to get good results working differently (a wheel that is basically flat “moves” more and maybe warms up better) and that driver should always give a hand, speaking out loud and saying his impressions, to understand if the right thing is being done.