As you can see, each point of view has its own weight in the discussion. But since weights are so important, how should we position the ballast on the kart? To do this, we need a weight balancing procedure that allows us to locate the correct positioning of the ballast. We went to Ghidella's workshop in Somma Lombardo where Emanuele Ciliberti, a telemetry operator, carried out this task (and explained it to us).
First of all, it is useful to put signs or marks on the ground (obviously we recommend a perfectly flat place) in order to identify the axles of the wheels and therefore the correct positioning of the shelves that will support the scales. You can use quality scales used for weighing people, those in the 0-100 kg scale with an accuracy of 0.12 kg, for a total cost of 100/150 euro, shelves included. It is important to check that each single shelf is level and that they are level with each other, horizontally and diagonally (obviously once they are correctly positioned, they must no longer be touched). Once the four shelves and the four scales have been positioned (always remember to check the batteries of the scales beforehand!), place the kart on top. Here the three phases of the actual weighing begin. First of all, the kart is weighed by itself, usually opting to weigh it without petrol. This is because the density and therefore the weight of the gasoline changes with the climatic conditions (1 liter of gasoline on average weighs 0.78 kg), affecting the total weight by even 1 kg.
In the first phase, the kart is weighed three times, noting the values of each scale. These three weight measurements make it possible to calculate an average that has an even more precise deviation for the purposes of the final calculations, neutralizing any inaccuracies of the scale itself or of displacements in the positioning of the wheels. In the second phase, the kart is weighed three more times, but this time with the driver fully dressed in a racing version. The third phase involves weighing the kart with the driver on it three times, but with an axle raised (for convenience, the front can be raised by placing two vertical wheels under the tires that raise the axle). This last phase is used to identify the center of gravity, or the center of mass.
Once the various weighing data have been acquired, the data are entered in a ready-made spreadsheet that will calculate values such as the total weight, the cross (the diagonals of the weights divided by the total), and the weight differences left/right and front/rear. These data allow the kart to be balanced in all conditions: not only front and rear or left and right, but in the dynamics of the diagonals, which are very important when the kart is moving on the track. It will be precisely with this data that the ballasts can be positioned in the best way. And you know, in karting the weights are positioned only on the seat with the double bolt. The important fact is that every centimeter or millimeter in positioning them has implications on the final set-up and overall balance. For example, if the spreadsheet suggests we move the weights to the front left, our option will be to place the ballast in the far front corner of the seat on the left. Furthermore, to improve the center of gravity (calculated in the third phase), you must always try to position them as low as possible. Obviously, the more ballast there is to put in place (or the smaller the seat), the less space to choose from will be available. A trick to achieving optimal results is to find the best seat positioning based on the driver’s size before the weight balancing stage. Obviously, finding a balance of 50% in each factor (right/left, cross, etc.) is the ideal theoretical result to be achieved, but in practice just think that a "little" driver will necessarily have to be further ahead to get to the pedals, changing in this case the distribution of the total weights. The calculations of the total weight obviously must always be done by calculating the petrol that will remain at the end of the race, including weights such as electronic equipment behind the wheel and the radiator fluids.
It is always advisable to balance the weights with the radiator fluids already present, also because there will be a difference in weight on the left side and also on the right side, as water enters the engine. The dimensions of the ballasts (and not just their weight) also influence the “work” of the seat and therefore of the frame. Furthermore, if heavy drivers are looking for special bolts to limit weight, for small drivers this type of accessories can have the opposite effect as it would require even more ballast. Once the ballast positioning operations have been completed and the three steps described above have been redone to obtain the new data to be compared (the operation may require various adjustments and different choices), it is advisable for a certain final reassurance to use the official track scale to check that the minimum weight has been reached, also because it is the one that will be valid in the race.
As you can guess, this work, a guide open to “Sunday” kart drivers, too, is truly professional in the true sense of the word. Some might argue that these measures go beyond the logic of karting, bringing them closer to the world of cars. The fact is that even if you want to race in a single-make, or rather perhaps above all there, in a tenth of a second it is easy to find ten drivers jockeying for positions. Thus, details like these become fundamental. Kart racing has evolved thanks to materials, processing, and design techniques and there is no going back in this respect. We can say that it has become a motorsport category in its own right and no longer just a simple passing-through or recreational category. Professional (but not expensive) procedures like these are now on the agenda. Nothing prevents you from still going for a run on Sunday without knowing how to position the ballast, but what we wanted to offer you with this article is the possibility to choose!