Multiple questions on Super Mario Kart Build

[OzFab]

Where did you get 0˚ camber & toe? You want 5-10˚ negative camber & about the same toe in...

 

[Slinky]

Okay so I weld it up the front axle to the Kingpin brackets at a 10 degree angle which in turn caused around 10 degrees of camber naturally in each wheel, I can straighten that if needed by ree welding the spindle stub at a flatter angle (more parallel to the ground), my problem now is what I believe is called scrub radius. I have because of the Kingpin angle around 3 in of scrub radius, this seems to be a lot am I wrong? I'm having a hard time finding a lot of information on what is a good scrub radius, some people say you can change it by wheel offset, but I don't exactly know how to change it to make it more towards zero.
How do I do this?
And is more towards zero what I want?

In the photos you can see basically what I'm talking about, ignore the angle on the spindle tie rod arm, it's stock and hasn't been modified to set proper Ackerman, I believe if I make it at the correct angle/hole location I can move the spindle farther into the wheel, would this give me a scrub radius closer to 0 ?
Or do I just need more KPI ?
(Also the spindles are tack welded on to the spindle arms, but the axle is not attached to the chassis yet)

 

[Slinky]

I made my own shorter spindles and moved the wheel further in towards the knuckle of the spindle, it changed my scrub radius from 3 in down to around 2 in now, I can notice by spinning the wheels that there is much less Kart jacking now though. I also welded the spindles so that they had a 5 degree angle built in so that it cut my Camber down to around 6 degrees instead of the 10 degrees that I had.
Is this what I want?
And the problem I see now is the trailing arms hitting the knuckle basically.

 

[Slinky]

This is what I ended up with, look correct?
Only tack welded in place.

 

[ezcome-ezgo]

I think it'll be fine. Nice job.

 

[OzFab]

Looks good to me; good work

 

[Slinky]

Ok thanks guys!
I will weld it up!

 

[Slinky]

My next issue is caused by the orientation of my engine. As you can see I mounted the engine 180* out for better fitment, cooling and aesthetics. This in turn caused the direction of the engine sprocket to turn the opposite direction (kart driving backwards)
As of right now I'm rather set on having the engine this way.

The following pics show my engine on the kart and a generic drawn photo of what I am thinking of doing with the chain.

Would this hold up?
Or is there another solution such as a gearbox that I can simply mount to reverse the drive rotation?
(Keep in mind that I would like to keep my gear ratio I have now if a gearbox is added)

 

[mckutzy]

You will experience premature chain wear, and as the chain stretches, The chain will potentially cause sprocket wear/skipping as there is less contact with most of the sprocket.
If the contact is kept to a full 1/3 diameter of sprocket(more the better)... It'll have a better life... As long as the idelers keep up(there will be alot of tension on these, so sprocket idelers will be needed opposed to rollers to keep from wearing).

In the end, fancy complicated chain setups don't work well.... I know... Took me about 1year to figure out on problem on my bike I built due to chains.

 

[Slinky]

You will experience premature chain wear, and as the chain stretches, The chain will potentially cause sprocket wear/skipping as there is less contact with most of the sprocket.
If the contact is kept to a full 1/3 diameter of sprocket(more the better)... It'll have a better life... As long as the idelers keep up(there will be alot of tension on these, so sprocket idelers will be needed opposed to rollers to keep from wearing).

In the end, fancy complicated chain setups don't work well.... I know... Took me about 1year to figure out on problem on my bike I built due to chains.

I was also thinking of possible trying to use a reversing gearbox if I could find one like pictured below, but have not had any luck finding one that would handle the RPM I need.

For the idlers I would be using 10T sprocket idlers on a rigid bearing housing, I would also try to wrap the chain almost halfway around the sprocket, I plan to put this into play on a 10-12hp build that could possibly go 50mph, when you say shorten the lifespan etc of the chain what kind of lifespan do you expect?
And does what I just said seem plausible to be reliable?

 

[Slinky]

I said I'm done giving a heck and turned the engine the proper way.

 

[Slinky]

Ok, thread back from the dead, the Mario Kart is finally almost done.
I have a couple questions now that I have actually driven it.
With the 5-7* of camber that I have built into the kingpins it makes the tire ride on around the inside 2" which I assume helps with handling, but I'm worried about the tire wearing out really fast on the contact patch, the 5-7* of negative camber in the Kingpin should transfer out to the axle bolt correct? Or the axle bolt should be parallel with the ground and just the Kingpin at a negative camber?

My second question is the steering is very Twitchy, my pitman arm is around 1.75 inches long (center of steering rod to tie rod mounting hole) and my spindle arms are around 3 in Long (center of kingpin to the time rod mounting hole), does this sound correct?
How do I make the steering less Twitchy?

(Photos above this post)

 

[OzFab]

Ok, thread back from the dead, the Mario Kart is finally almost done.
I have a couple questions now that I have actually driven it.
With the 5-7* of camber that I have built into the kingpins it makes the tire ride on around the inside 2" which I assume helps with handling, but I'm worried about the tire wearing out really fast on the contact patch, the 5-7* of negative camber in the Kingpin should transfer out to the axle bolt correct? Or the axle bolt should be parallel with the ground and just the Kingpin at a negative camber?

Did we not cover that?

Two possible answers here:

1. You could go parallel or, a degree or two of upward inflection; adding a small amount will give you more road contact but, with negative caster built in as well, depending on the degree, you may end up with the inside of the inside tyre leaving the ground...
2. If you also have negative caster, as you turn, the inside wheel should flatten out on the road surface...

My second question is the steering is very Twitchy, my pitman arm is around 1.75 inches long (center of steering rod to tie rod mounting hole) and my spindle arms are around 3 in Long (center of kingpin to the time rod mounting hole), does this sound correct?
How do I make the steering less Twitchy?

That means that for any movement of the steering wheel, you get almost double the amount at the spindle; for best results (ie: not so sensitive steering) the 3 arms should either be the same length or the pitman arm longer than the spindle arms...

 

[Joe-405]

Less twitchy = using a steering damper off a sport bike. Will work well. What ozfab is saying will help also.

 

[Slinky]

Thanks for the quick reply!
I just fear with my 5-7* of camber on the tires I will wear thru the tires fast joyriding on the road.
The cart literally steers and reacts so fast now that I turn the wheel around 1-2" max ever. I was thinking it was mainly to do with pitman arm length, but didn't know if the camber had anything to do with it.

What I was mainly concerned with is if I got rid of most of my Camber at the wheels (and still keep the kingpin 5-7*) to prolong the life of my tires, would it kill my steering/handling since I do have proper ackerman, caster and kingpin negative camber.
Sorry if this was answered before.

 

[OzFab]

Ok, have a look at this post, particularly the pics; that should answer your question...

 

[Slinky]

Ok, have a look at this post, particularly the pics; that should answer your question...

So you have most of the camber built into the C brackets and 2* of camber in the actual spindle arms.

The way I have mine most of the camber (5*) is built into the spindle arms and only 2* built into the C brackets I believe.

EDIT: I have to recheck that, I think I have 10* in the C brackets and have the spindle arms welded to where they end up with 5-7* camber.

 

[Slinky]

Okay I just checked, the C brackets have about 10 degrees of negative camber in the wheels have about six degrees of negative camber.
I just changed the Pitman arm length and pretty much doubled it and it did not help, could there being too much camber be causing it to be so Twitchy?

EDIT: I drilled multiple holes in the pitman arm to have adjustment, I moved it to the closest hole to the steering shaft and put a slightly bigger steering wheel on, a 12 inch steering wheel and it seem to be less Twitchy then it was being further away from the steering shaft. It's still really sensitive though.

 

[OzFab]

Ok, at this point I must apologise to you for giving you false info & wasting your time, I had it backwards (I can't believe no one pulled me up on this)...

With a shorter pitman arm, you should have less turn at the spindles compared to the steering wheel; for example, if you have a 2" pitman arm & 4" steering arms on the spindles, for every degree of rotation at the steering wheel, you will achieve 1/2* at the spindles (so, a 2:1 ratio)...

With all three arms the same length, the ratio will be 1:1 (duh)...

With the setup reversed (4" pitman arm & 2" steering arms) the ratio becomes 1:2 (1* at the steering wheel = 2* at the spindles), which would, indeed, give you "twitchy" steering...

Now that we have that out of the way, let's try to discover why you have twitchy steering; how is the toe aligned?

Looking from the front of the kart along the length of the kart, are the front wheels parallel, pointing in or pointing out?

 

[Slinky]

Okay so when I came out to this morning I realized I can move the front wheels more towards the center line of the Kart, I move them in about an inch per side, I'm not sure if my scrub radius has anything to do with what is happening. I now have around 2 in from where the Kingpin would touch the ground to the Centerline of the tires.
If this will affect my Ackerman steering greatly I can switch it back I'm just not sure if the scrub radius has anything to do with the over sensitive steering.

Some more info on the cart that might help is I have a 12 inch steering wheel, the front tires are 10.5x4.5, rear are 11x6. My track width in the front and rear is 37"-38" and length between front and rear tires is around 52". I have around 10* of caster and 10* of camber in my C brackets. I have around 6* of camber in my front wheels. My tie rods are virtually parallel with the ground and almost in a straight line across the Kart underneath. The distance from the steering shaft to the pitman arm hole is around 2" and the distance from the Kingpin to the whole in the tie rod bracket is around 2.75". And last I have about .25" toe in per side meaning 1/2" closer total in the front of the tires vs rear of the tires.

Again I'm not sure how much any of this info will help on finding out why the steering is so crazy sensitive but the more info I can give the better chance I have of getting an answer.