Jacking vs. grip

During our covid track closure, I tried to read up on the basics of turning. What I think I understand is that, once properly jacked for a particular corner, maximum grip is a function of (1) balance (no push, no oversteer) plus (2) tires (model, wear, psi, heat, camber, toe, etc.) and (3) track surface (green, rubbered-up, dusty, etc.). Granted the driver’s style enter’s into this (mine would be described as mild panic), but assuming a smooth arc for a particular corner’s radius, then, as I understand posts in this forum, chassis set-up is all about when, how much, and how fast the kart jacks and when and how fast it comes down on 4 tires. I trust I’ll get some strong pushback on what I’ve just written, but my question is still to come: Can you get the same kart to “properly” jack (i.e., jack the same) using quite different approaches to set-up?

Sure. If you want to increase jacking you can widen front, increase caster, add front torsion bar. They may different effects still. Narrow with more caster means you essentially have higher center of gravity than wider with less caster. So narrow means your body weight will transfer more weight. So same or similar effect at turn in but different later. So maybe need to lower seat reduce weight transfer if narrow. A lot of ways to get there

Good question. As Todd said, yes, there are many ways to skin the cat. Of course, the laws of physics still apply so there will be limitations or requirements that a kart needs to jack properly. Driving style and driver build make a big difference in how you can set up the kart.

One example off the top of my head: I once had a teammate who was almost always the exact same speed as me. However, I usually would run max caster and wide front end and he would run neutral or even negative caster and a narrower front end. Again, we were almost always within a tenth of each other, and both were fighting for podiums at big races, so it wasn’t like we were out-to-lunch. The reason for the differences in setup was down to a few things. He was taller than me, so he was able to use his body more effectively to jack weight. He also had a more aggressive turn-in style, where he really drove the corner entry hard with a firmer wheel input. I was smoother and tried to tip the kart into the corner gently and progressively. Because of those factors, I needed the kart to mechanically work harder to lift the inside rear. His higher CoG and his more aggressive steering input meant he needed less front end on the kart. If I drove his kart, I would’ve found it to understeer massively. If he drove my kart, he would’ve found it to be too twitchy.

I’ve seen some drivers with really aggressive driving styles run setups that are completely off-the-wall and out of what most would consider the “tuning window”. I remember specifically a couple years ago, we had a driver do an arrive-and-drive on our OTK kart and he complained that there was too much front grip, literally every session. It got to the point where we took the front bar out of the kart, which was a totally bananas thing to do on an OTK kart. 90% of people would say that wouldn’t work. But he loved it and went the fastest he had gone all weekend.

What would you say to the question; can I get a girl to like me more by using different techniques? Can the answer be anything other than “maybe/maybe not”.

Just look at all the ideas you see here on Bob’s for doing exactly the same “thing”, whatever that “thing” is!

And of course everybody has their own ideas of what is “properly”. I only know of one way to judge what is “properly” and that is lap times. If you get fast time, you’re most likely doing something “properly”, not always, but often.
And I should say “most properly” because if you get fast time, that doesn’t necessarily mean you’re doing it “properly”, just that you’re the closest to “most properly”.

What matters are the four wheel loads, the four tire temperatures, the four tire slip angles, the four tire camber angles, and the distances between the center of the contact patches and the center of gravity.

Those will produce a net lateral force on the kart, and a net moment about the center of gravity. Make those the same at any given point in the corner and it will handle the same way there. If you make the front tires contribute more of the same total lateral force, you’ll get a larger yaw moment and it’ll be looser. If you make the rear tires contribute more it’ll push more.

If you lift the inside wheel off the ground it cannot contribute to either lateral force or moment, so your wheel loads on the other three are statically determinate and the only things you can change are the front wheel slip angles and the rear wheel’s longitudinal force. When you go from four wheels to three you get rid of the wheel that gives the largest understeer moment on the kart, so if you’re neutral on three wheels at neutral power then you’ll need to introduce an oversteer moment somehow to get the kart to rotate well on four. Either pedal can give you that.

In my opinion this may be a little misleading. If I am over steering I still do not want to touch down the inside wheel to gain under steer. Touching inside wheel bogs down kart. Try pushing kart and turn wheel. It just about stops. So reducing understeer is about getting the outside wheel to work better. For example staying flatter even while lifting inside wheel. Slowing down transition to the outside wheel some so as not to shock it. Those are just a few examples