Crosskart Xtreme best center of gravity height?

[modok]

Maybe you could redesign the rear suspension so the brakes have anti-dive, preload it on the brakes for the launch and make it squat.

[Tom68]

It's a weird question, what are you going to change ? You need ground clearance, you need suspension travel, the buggy has been built with arm angles to suit a certain ride height.

The cart is an older, lighter model that we bought from a heavier driver and our driver is young and light (and very fast). Consequently, we can install heavier components anywhere as the previous owner got the cart without a driver as light as possible, to the edge of reliability. This gives us some ability to shit the center of gravity height, from installing a heavier rear wing to adding lead plate ballast to the floor plate.

The ground clearance is measured at the end of the suspension travel if I recall correctly. Since the springs are free, it's not usually bottoming; except in the big jumps on some of the Swedish tracks.

Any added weight above minimum rule requirement raises the cog which should always be as low as possible.

Added weight is for front to rear balance or side to side balance.

If you want to add weight for the starts put it as far back as possible that way you won't need to add much.

[ptuomov]

Any added weight above minimum rule requirement raises the cog which should always be as low as possible.

If you want to add weight for the starts put it as far back as possible that way you won't need to add much.

Assume that the car is always at the minimum weight. There's enough flexibility to move weight around.

My question is at which point is it better to improve the traction at start by moving CG towards rear vs. moving CG up?

Both will improve traction at the start, but one may hurt the flying lap more than the other per improvement at the start.

[Tom68]

Any added weight above minimum rule requirement raises the cog which should always be as low as possible.

If you want to add weight for the starts put it as far back as possible that way you won't need to add much.

Assume that the car is always at the minimum weight. There's enough flexibility to move weight around.

My question is at which point is it better to improve the traction at start by moving CG towards rear vs. moving CG up?

Both will improve traction at the start, but one may hurt the flying lap more than the other per improvement at the start.

Any added weight above minimum rule requirement raises the cog which should always be as low as possible.

If you want to add weight for the starts put it as far back as possible that way you won't need to add much.

As low as is practical, as far back as possible.

[ptuomov]

As low as is practical, as far back as possible.

Why is that obvious?

[ptuomov]

Manufacturer’s photos of the basic car:

https://www.speed-car.com/xtrm-e.html

[Rick!]

Do u have a link to the official Extreme kart rules you can share with us?

[ptuomov]

Do u have a link to the official Extreme kart rules you can share with us?

Example rules for the Nordic series:

https://www.autourheilu.fi/site/assets/ ... t_2023.pdf

[ptuomov]

My observation and logic says that the factory designed the roll center geometry as if the car would be a front-wheel drive car. They is, a higher roll center in the rear than in the front. This is necessary as the lack of differential means the inner rear tire must lift and slip in turns.

[ptuomov]

Images of how a front-wheel drive car is set up and how this crosscart appears to be designed from the factory:

wishbone-ic.jpg

wishbone-rc.jpg

fwd-roll-centres.jpg

rear-wheel-lift.jpg

[BCjohnny]

In the vast majority of cases the rear roll centre is higher than the front, in both FWD and RWD vehicles

Very rarely is it the other way round, IIRC mostly rear engined

I've come across various reasons why this would be so, but 'feel' near the limit is generally more natural for the driver when set up this way

[Tom68]

Identify the handling problems then address them.

1. Reduce start line wheel spin.

2. ?

[ptuomov]

In the vast majority of cases the rear roll centre is higher than the front, in both FWD and RWD vehicles

Very rarely is it the other way round, IIRC mostly rear engined

I've come across various reasons why this would be so, but 'feel' near the limit is generally more natural for the driver when set up this way

I drive a lot of Porsches (not well or fast) and I think those have the roll center higher in the front than in the rear.

I think that the track cars that lift the front wheel when cornering on track likely have the front roll center higher than rear roll center. All those cool photos with the inside front wheel in the air…

https://www.thedrive.com/guides-and-gea ... -cornering

“Picking up a wheel, inside front (typical BMW) or inside rear (most FWD cars), is a natural occurrence of dynamic weight transfer," Rodriguez said. "It is not necessarily a bad thing. You know it's going to happen and just drive through it."

[ptuomov]

Identify the handling problems then address them.

1. Reduce start line wheel spin.

2. ?

2. Without seriously increasing the flying lap times. Currently the car is basically as good over a flying lap as our noob moron setup skills can ever get it.

[Tom68]

Roll center.

EDV-CR110.jpg

Cars don't body roll around a center that's on the centerline of the chassis.

These ones almost did, until they start to roll and the slides on an angle.

images.jpg