Throttle for turning kart while driving in the wet?

[volarchico]

I've done a lot of reading about racing, and playing of simulators, but do not have much experience with the actual thing. The other day I was out at a kart track in the wet and was hoping for help explaining the technical reason for what I experienced.

Usually, you're taught to brake in a straight line, then turn in and slowly add throttle at the apex.

However, with the kart, I would brake early on the straight and try to turn in and experience massive understeer (the kart would not turn at all). Through trial and error, I eventually figured out that I had to apply power very early to get the kart to go around the wet corners at any appreciable speed.

From my limited amount of understanding, this is counter-intuitive. Applying throttle I would imagine shifts the weight backwards, making the front even lighter and more prone to understeer. I don't think I was inducing oversteer, because I didn't have to counter-steer to catch the back end; I was still steering into the corner while applying throttle.

Can anyone help me understand the dynamics of what was going on?

[Caito]

You don't have to forget that a karting has no differential. So it basically wants to run in a straight line.


That's why kartings are set-up to lift the inner rear wheel. In that way you would avoid the drag and understeer caused by the lack of a differential.

In lifting the wheel there's a couple of elements that help to achieve the result.
With caster the outer front wheel lowers, generating diagonal weight transfer. KPI causes the opposing effect, but caster prevails. KPI is necessary anyways because of two main reasons: scrub radius, which provides feeling to the driver, and the self-returning action of the wheel (since the straight ahead position is the lowest).

These two effects remain in the wet or with a dry track. But there's also weight transfer that help lift the rear wheel. Since you don't want to lift the wheel too much it barely leaves the ground. What happens is that with a wet track, when you're going slower the wheel might not be lifting at all, you'd have to go faster, which is impossible because it's raining.



I'd suggest having someone take a picture and see if you're lifting that rear wheel. It might a first step in knowing what's going on.


Some things I'd like to know. Where you taking the some line that you take when it's dry?
When you tried the throttle thing, were you taking the same line you took when you were having understeer?


Try applying a lot of steering lock(even if it oversteers) because that produces the maximum jacking effect on the karting, then the karting might get a grip and turn suddenly.


One of the reasons why getting some throttle might work (basing on the supposed fact that you're not lifting the inner rear) is that you're overcoming the drag and push effect caused by that wheel, hence reducing understeer.

[volarchico]

Thanks for your excellent reply. I'll see if I can get someone to take pictures next time I'm out. To answer your questions I was using basically the same line as in the dry. Also, I was not at full steering lock because I was already under steering so I had to back off the steering input and increase the throttle. I think your description might be it...the throttle was making the back end just loose enough in the wet that it would slip around.

[Caito]

Thanks for your excellent reply. I'll see if I can get someone to take pictures next time I'm out. To answer your questions I was using basically the same line as in the dry. Also, I was not at full steering lock because I was already under steering so I had to back off the steering input and increase the throttle. I think your description might be it...the throttle was making the back end just loose enough in the wet that it would slip around.

If it's a track where a lot of karters go, the regular line will have rubber in it. That makes it faster in the dry, but it's not in the wet. Wet rubber doesn't grip.

Even though you're understeering, applying more lock might be good because you help lift the rear wheel. Karting is counterintuitive, you know. The same happenned to me, but it all becomes logic once you find the correct explanation.