Weights/seat position

The weight positioning in the kart has a certain importance.

The main weight is the pilot and it counts for a 50% of the total weight. And the positioning of this weight can be varied, moving the seat: higher or lower, more to the front or the back.

Raising or lowering the seat has more or less the same effect than raising or lowering the kart from the ground. Moving to the front or to the back the seat, it means loading more the front wheels (and generally it can be said a better front grip can be obtained, to the detriment of the back one, so it’s useful moving the seat to the front if you have a lot of understeering, especially in tracks with slow bends) or loading more the back wheels (these wheels usually support the main part of the weight, and so the effect will be the opposite than the effect you get moving the weight to the front. It can be useful in tracks with fast bends, where your kart doesn’t have a lot of grip with the back part during these bends….).

Anyhow the driving position has to be very comfortable, even if you are going to loose some “points” in reaching a perfect driving position.

If you cannot reach the minimum required weight (of course if you are interested in competitions), you can put the weight in a more strategical way. The regulations (for races, but you can assume these rules also for the “Sunday drivings”……), in order of having a certain degree of safety, impose of having the weight fixed to the chassis. Actually all people fix it to the seat but you are not obliged to fix it to the seat (and the seat it’s not really a part of the chassis). So, let’s suppose we want to load more the front part, you can fix the weight plate moved to the front or wherever you want. It can be useful if you have understeering, but you cannot move the seat to the front, because you are already too close to the steering-wheel and the driving position could become not comfortable.

Then an additional weight is generally put on the opposite side of the engine, so the kart is balanced; this choice is not always the best one. For example, let’s suppose we are driving in a “nascar” style track, which is an oval inclined track; in these tracks, cars have a weight put on the left side (rotation way in the oval), so the car is “kept inside the track”, while it’s running in a parabolic part. Now, we don’t have this kind of extreme tracks in kart races, but it could be useful having a kart with a certain degree of easiness in steering to one side instead of to the other one and the weight positioning can help. Based on the track features, I’m not so confident in how to put the weight: probably I’d make an attempt. Anyhow, we are talking about details, in comparison with the main driving position regulation.

Other things

The most difficult and expansive regulations are the ones related to the front wheels incidence and to the axle hardness. Let’s say under the title “Other things”, I put something on which I don’t have a direct experience and a good knowledge.
Actually, the regulation of the angle incidence is not so difficult; you have to act in the same way you operate on the camber angle, but setting the ear-ring/bush eccentricity in a way they are rotated of 90°. Personally, I’ve never changed the incidence and I don’t know the kart reaction after it, also because this feature is something only affecting the karts. Anyhow the kart has already a basic incidence angle, which has the purpose of loading more the front wheels. The incidence angle can increase the front grip with hard tyres, or better there are people who assure a certain additional grip is necessary with that kind of tyres.
What is very important and deeply affecting the kart, is the axle regulation, which means the axle flexibility. There are a lot of axle types, and they are categorized based on their hardeness or flexibility. We can affirm a hard axle has the same effect than hard gimbals and vice versa. If your kart has too much grip, generally it’s better using a soft axle, vice versa a hard axle is advisable. The measures you need to keep in mind regarding an axle are two: the external diameter and the thickness; these measures are usually written in this order: external diameter / thickness. The axle replacement is a very expansive operation, regarding money, time and effort (you need to buy a new axle and disassemble everything from the old axle and then assemble on the new one).
As last thing, you can act on the anti-intrusion back bar; if you fix it very hard, without any clearance, the back part of the kart will be inclined to slip more, while if the bar is left more “slack”, the back part of the kart will have more grip.

And finally I cannot say anything concerning the brake distribution in the 125 category.

In conclusion

The difficulty indicates, not simply how difficult is performing the action, but also how difficult is doing the regulations and testing them.

The necessary time indicates, more or less, the time you need to complete the operation.

The impact indicates how much the regulation/action can influence the total kart driving position (in a positive or negative way).

The cost is the likely operation cost.

Of course, we are talking in a general and subjective way.


ACTION DIFFICULTY TIME IMPACT COST
Front ground height Low 20 min Low Nothing/Min.
Back ground height Medium 30 min Low Nothing
Axle Medium/High Undet. Medium Axle (90 euro)
Back bar Low 5 min Medium/Low Nothing
Camber angle Medium 20 min Medium Min (+ disks)
Convergence Low 10 min High Nothing (+disks)
Front width Low 5 min Medium Nothing/Min.
Back width Low 10 min High Nothing
Weights positioning Medium Undet. Medium/High Nothing