king pin inclination

As Racing Promoter stated its going to be a lot of experiments and minimal or worse results . Handling problems can be corrected much easier then spindle changes .
If you want to learn its benifical to look at all aspects .
Scrub will be a line through the king ping projected to the ground . The distace from where it contacts the ground to the center of the contact patch is the scrub radius. Inside the cenerline is positive , outside is negative .
I'm going to say scrub is related to tire loading .
 
Its actually a pretty complicated process .
King pin inclanation , along with caster and camber also affect , weight jacking .
Tire presantation , timing of loading and unloading of the left rear .
 
flattop1 said:
Its actually a pretty complicated process .
King pin inclanation , along with caster and camber also affect , weight jacking .
Tire presantation , timing of loading and unloading of the left rear .
Click to expand...

It's not complicated at all if you use the correct Paul's racing finger puppet. ... :)
 
With 12° kingpin inclination and no Castor, this is the arc the spindle makes. The distance of .3777" is from straightahead to 45° turn. Of course nobody ever turns 45°, I realize that, it's just for illustration purposes. People, a lot smarter than me, should be able to formulate a method for calculating this.
12 DEG kpi.jpg
 
tbyji2 said:
Here is a diagram . With some of the nuances. View attachment 7342
Click to expand...

Thank you for years I've seen the relationship between KPI, weight jacking and tire presentation at needed camber gain using LOL my finger puppets. You have put numbers(and a written down idea) to what in the past I only was able to visually see.

What you use(camber, castor, kpi, ackerman) and what you do is IMHO dependent on the track design especially when and how you get involved with banking.

It makes the main trade offs to always lean toward first the resulting end camber and secondly when camber gain occurs. The driver can't do much about the amount of resulting camber. But they can via vehicle placement at turn in cause camber gain to occur at what I'll call, a good place on the track.
 
racing promotor said:
I don't know enough about it to speak on subject but My question would be WHY your asking, If your asking just to learn more about it and gain knowledge GREAT !! But if your asking because your lacking speed with your program and not satisfied with your results, your barking up the wrong tree, I point this out in only trying to save you more frustration as it's not going to get you end result you would be looking for.
Click to expand...
Had some knowledge of KPI from an A arm system. But nothing on karts with no moving parts. Looking to know more for possibly building my own kart
 
Al you still don't get it. We all understand Scrub Radius and how tires are about loading or pushing onto the tire and the track pushes back per how the tire is gripped to the track.

The conversation on here Al has long ago moved from what it is and how to change it. What the original poster asked about is how it's changed, how it functions on an "OVAL" track and why you use it in differently for different "OVAL" track conditions.

Thank you for trying to teach all about scrub radius. Can you try to open your mind up and learn how "OVAL" racers use scrub? If you want to talk about how sprint chassis work, there's an appropriate section on here. Or maybe go to I think EKG karting or something like that if you haven't been thrown off the sprint site again. How about some common courtesy?

All your doing at this point is more of your talking down to people. Do you have such an inferiority complex from when you were a kid you now have to continually demand acceptance from others, even when you know what your presenting is not accepted as correct?
 
Tell you what Al. To make many many readers on here happy and give them a great Christmas present.

I'll stay off this site and not post for a month until January 24th if you will?

I'm sure for many i'm just as annoying as you and it would be a nice Christmas present.
 
There was a kart built, sorry, an oval kart built with 0 or almost 0 degrees of kpi spindles. The trick was super low RF caster like only 2 degrees and typical 6-9 degrees LF caster. Everyone I ever heard talk about running it said it turned free a quick like a wheelchair.

CKI for a few years actually had a NEGATIVE 2.5 degree LF spindle that was available.
 
King pin inclination (KPI) may have something to do with automobiles, but I wonder if it has anything to do with karts. Karts have quite a bit more Castor than any automobile. In my illustration, I hope you can see how far the purported "scrub radius" is from the point shown in the illustration. With 12° Castor and 12° KPI, as in the drawing, I don't believe there is a "scrub" point around which the tire is turning. I believe the tire is rolling, not twisting. The tire in the illustration is 6 inches wide with a circumference of 36 inches.
SCRUB RADIUS.jpg
 
And, might I point out, with no kingpin inclination that "scrub radius" would be even larger. I don't even think there would be a scrub radius.
 
barluc99 said:
Not too many kart racers on here familiar with Columbiana, we would race Slippery Rock saturday nights then show up to Columbiana with dirt still on the karts and get strange looks haha.
Click to expand...

Columbiana was the first kart track I ever drove on with high hp -- a Formula A setup. Courtesy of Rob Bank, former Birel dealer, out of Pittsburgh, PA. Circa 2000.

Anyhow, karts have a fairly large scrub radius. If a line is drawn along the KPI axis, and another drawn from the center of the tire down to the ground, there is ZERO scrub radius if the intersection occurs at that point. Usually, from what I've seen There's about 3-4" scrub radius. Becuase it occurs on each side, the drag force cancels and steering isn't overly heavy except from castor effects. Karts have evolved on the sprint side -- try driving a 90's kart vs. one of todays and the steering effort is MUCH harder. Some of this has to do with the ackermann columns now in favor. I'm sort of curious why LTO karts haven't moved to an ackermann column.
 
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scottiedout said:
There was a kart built, sorry, an oval kart built with 0 or almost 0 degrees of kpi spindles. The trick was super low RF caster like only 2 degrees and typical 6-9 degrees LF caster. Everyone I ever heard talk about running it said it turned free a quick like a wheelchair.

CKI for a few years actually had a NEGATIVE 2.5 degree LF spindle that was available.
Click to expand...
Now that sounds interesting might have to look into that
 
scottiedout said:
There was a kart built, sorry, an oval kart built with 0 or almost 0 degrees of kpi spindles. The trick was super low RF caster like only 2 degrees and typical 6-9 degrees LF caster. Everyone I ever heard talk about running it said it turned free a quick like a wheelchair.

CKI for a few years actually had a NEGATIVE 2.5 degree LF spindle that was available.
Click to expand...
I wonder about wwhat year was this ?
Tires have changed quite a bit , thats something to factor in as well .
No caster , would that lead to the speed wobble .
 
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