I will answer 1 of the many questions.
The flat bar is sort of a Multi-bar.
Flat is softest, 45* is stiffer, vertical is stiffest.
I always start with it in 45* if I need less grip I turn flat, more grip turn vertical, if I need even more I go to adding caster and even more the go to the stiffer round bars.

There is no better or worse, its about keeping the kart balanced and fast with the changing track conditions.

As usual Brock, you’re making it harder than it needs to be ;)

I run the flat bar all the time. I start with it flat, turn it to 45 if I need more front grip, turn if vertical if I need even more front grip. This weekend I ran it horizontal in the dry, vertical in the rain.

Anytime you go stiffer in the front, you are adding grip.

Always set the kart up neutral and tune to the track conditions, as Matt said. The OTK kart works with a neutral setup like 95% of the time.

From a green track on Friday morning, to a hot rubbered in track this afternoon, I changed from 6˚ of caster to 3˚ of caster and I narrowed the rear 4mm. That’s all we changed all weekend.

Brock,

Below are the bars soft to stiff (someone correct me if I’m wrong in the order here), but the stiffer you go the more front grip.  On greener tracks you’ll be stiffer on “rubbered up” tracks you’ll be softer.    We don’t mess with any bars other than the gold and flat bar.

flat bar placed flat
round bar 1
round bar 2
flat bar 45 degrees
round bar 3 (the gold bar)
flat bar straight up.

Also, wider front width, more castor, more positive camber equal more front grip.  Less front width, less castor, more negative camber (or less positive than you had) equal less front grip.

On your changes you made last week, everything you did removed front grip and your kart went faster.   You essentially were “freeing up” the kart.

I run a Tonykart 2014 in TAG, I’ve been running KRA @ NewCastle.  Track has been green all year.  One race I ran the flat bar 45 degrees, the rest of the races I’ve run the gold bar.  I’m typically at -1 click, neutral, or +1 click camber.

I’ve been confused as well at how they all work together but if I just need a little more little less front grip I change one click on the camber.  If I feel I’m further off I’ll change the bar.   If you’re all the way soft on the bar I’d change the castor next.  If you still have too much grip your seat may need to be remounted.

– Dave

I believe we often simplify our understanding of “adding grip”.   The where and how it adds grip is often more important.

FOr example, adding castor really doesn’t add front grip.  It increases the weight jacked on the inside front tire as well as increases the speed at which that weight transitions.  This will help the initial turn in (which people often think of as grip but isn’t).  However, be aware that it also increases the weight that arrives at the right rear.   Turns in good but may bind and even hop.  Get it right it turns in well and then returns the weight it the right time to get good forward bit off the corner.

COnversly, stiffing the front bar doesn’t actually add front grip.  It stiffens the front and resists weight transfer.  In doing so, you help prevent some weight from moving to the outside front tire that can cause overload it causing it to slip.  This helps the front primarily at apex and exit but will do nothing for turn in.   I like to think if the front bar as a broom handle, which one adds more grip to the broom head?

Chris is correct.

The tires always have the same amount of grip. You are never adding or taking away grip from the tires unless you are changing the compound or softness of tires. The only adjustment that affects that is tire pressure.

You are only affecting how the chassis flexes and uses the grip available. This is why I don’t like talking about adding or removing grip; I prefer to talk in terms of adding or taking away inside rear wheel lift. Because it isn’t always cut and dry. Sometimes a handling adjustment might have the opposite effect you were expecting.

If you are “taking away grip from the front” you aren’t always “adding grip to the rear”. You are just changing the relative balance.

For example, adding caster increases your perceived front grip on turn-in. This isn’t because you are adding grip to the front tires, you’re just increasing the weight jacking to the rear, allowing the kart to react quicker. This can either dig the outside rear tire in harder, resulting in a better “dig” in the corner and more side bite. OR, it can result in you overloading the outside tire too quickly, making the kart lose traction and slide. These are two opposite handling issues caused by the same adjustment, because it all depends on track conditions and the rest of your setup. There’s always so many variables at play.

Adding grip to the rear does not mean taking it away from the front unless you are moving the seat back (or forward).

Most kart adjustments are not about adding or taking away grip but rather where/what you are doing with the weight that is unloaded from the inside rear.    For example, adding more negative camber as the track grips up means moving less weight to the outside rear and towards the outside front.  The weight may not always get to the outside front because once the driver unwinds the wheel, the weight is being shifted back to the inside rear.  Therefore, I have taken away weight (grip) from the outside rear, moved a little to the outside front, and kept much of it suspended in the frame = free.

TJ,

I am curious about your comment about moving the rears in 4mm when the track gripped up.  While this is a very slight adjustment, I am curious as to what the purpose was.  Conventional wisdom of course is to run full width (lower center of gravity, more resistance to weight transfer) when things grip up.

Not questioning the effectiveness, just what to understand your theory.

Chris,

We’ve found the MG tires to start to fall off pretty quickly, especially at Shawano, and as the day goes on, we start to lose sidebite and the kart begins to sit flat. We narrowed the rear to try and get more sidebite. The tires were falling off quicker than the track was building rubber.

Thanks, that’s an interesting observation.