We continue to publish the extracts from the technical articles that you find in the latest issue of Vroom International. This extract is taken from ‘Don’t let it freeze’, which is about some precautions to face the lower temperatures of this time of year. Here you find some more practical aspects to be taken care of such us tyre pressure and chassis set-up.
OUGHT WE DO THE PUSH-UPS?
Staying on the subject of “wheels”, don’t forget that as a consequence, tyre pressure has to be adapted. There is no real mathematical rule that tells us how much the pressure has to be varied by according to external temperature, but it is true that when temperatures are low you must put slightly more air into the tyres. 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). So the hotter the tyre, the more the air expands and tyre pressure increases. Obviously, when it is cold, it could remain too low.
To start with, we might just increase pressure by a few points (tenth of a bar) but ideally, you should test wheels when warm, that is when you have stopped and check the pressure then and compare that reading with previous readings(we have done this haven’t we?). 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 bearing in mind that in this case too, it is 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.
The function of tester is very important in adjusting and seeing the different opportunities there are through kart set up. For example, the flexibility of the chassis: modern karts enable us to do almost anything we like in this sense, either by tightening or loosening “strategic” screws like those on the bumpers, or mounting (or not) supplementary bars; different types of bars or the direction of the same. The latter is a quick adjustment to see in which direction you have to go: usually, if you mount a lower added bar it makes the chassis stiffer and gives more stability (hence the name given to them by some “stabilizing bars”), but in some cases, say when there is less grip due to cold weather, it may happen that the chassis doesn’t work properly because there is less stress, therefore, you end up with less grip.
The sensitivity of the person who is driving is very important for this; he helps mechanics to understand if the chassis is “working” properly or not, so he helps to see if there are any problems with set up.