Let's talk about Seat Position

(James McMahon) #63

How is the kart actually handling and how do the tires look. You don’t always have to obviously visually lift the wheel, rather you’re looking to unload it.

Like anything other stopwatch has final say. Broadly speaking you add caster or front track width for entry to apex and control the unloading from apex to exit with the rear track width.

(TJ Koyen) #64

Tend to agree with James. What tire are you on? I’m assuming something harder if you’re running an STVK. On a harder tire, a kart isn’t going to jack weight like it will on a softer tire. If your weight distribution is as it should be, and it sounds like it is, then I wouldn’t worry too much if your pace is fine.

On the harder tire you’re not necessarily going to see it truly lift the inside rear, sometimes just getting the tire light enough that it isn’t scrubbing is all you can do. But if you need more jacking, a stiffer front bar or adding caster will both achieve that. It’s pretty much guaranteed to lift if you add caster and stiffen that front bar.

(Liam Sergeant) #65

That sounds like the seat is set quite low for someone so small? I’m not giving advice, more looking at what people think. I’ve seen kart set ups whilst I’ve been researching that had small drivers spaced way up high.

I think James and TJ are providing great actual advice though. I’m just learning and find different approaches interesting.

(Kevin Pitta) #66

I’m curious about that too. I probably should raise the seat some more, but how do I know when it’s too high?

(James McMahon) #67

You’ll find your driver will be chasing the rear as the inside wheel unloads excessively, perhaps even to the point that the outside tire isn’t sitting square on the track.

Before you change anything, be clear on the problem you want to fix? Is it on exit, or entry. Perhaps both. But either way, figure that out and make changes accordingly.

Also… are you sure the chassis is square?

(Matthijs Hofman) #68

Since it’s been quiet for three days in this thread, I dare to ask a new question.

In my experience, normally placing your seat forward means more grip to the front wheels, means less understeer. But I read somewhere that Australian racer Col Fink from Kracer mentioned that (in certain cases?) you should do the opposite: put the seat back when experiencing understeer and the other way around.

The basis of this theory (out of my head, because I cannot find the original article) is: when you are understeering you already ask too much from your front tyres, so by placing the seat forward you put even more pressure on the front tyres making the understeer worse.

Can you guys enlighten me when Col’s theory works? Or is my experienced skewed from spending too much time in rental karts? Normally the only thing you can adjust in a rental kart is the seat position, so that’s why the answer to this question is so essential for rental karting.

(Eric Gunderson) #69

I think the best way to figure this out is to test, ideally with a tire temp data logger…move the seat back and forth and note how the tires heat up and fade over multiple tests to see if there is a certain ‘tipping point’ where you simply exceed the load limit of the tire.

It makes sense from a race car standpoint…but when you factor in that the chassis ‘hikes’ and flexes, I’m a bit more skeptical. However,_ the fact that karts can hop or bind on corner exit does suggest that there is a lot more at play with all of these factors than we may understand…or rather than I currently understand.

My suspicion is that this might be a possibility with heavier drivers in particular, or with taller drivers, as they tend to ‘roll’ the chassis more around the front tires.

The more I think about this, the more intrigued I am to hear other’s thoughts!

(James McMahon) #70

It’s like any adjusment, you just reach a point of diminishing returns. Of you’re already close to that point before making the adjustment… then it might make the situation you’re trying to remedy, worse