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So, if the tires can only withstand .9 g's and that translates to, let's say 800 lbs of weight transfer, then just how can one wheel be off the ground?
It's not that complex. First, the .9 g's assumes that all four tires have exactly equal traction. They don't. In the case of the coupe, the rears have more grab than the fronts. So, let's say that the rears can attain a grip withstanding 1.1 g's, while the fronts can handle .8 each. Now, as you increase weight loaded on a tire, it's grip also increases. Let's say for argument's sake, adding 25% weight increases grip capaicity by 25%, or from 1.1g's to 1.2.
On a 3100 pund car, static weight is essentially 775 pounds per wheel.
In my first post I noted that maximum weight transfer at 9 g's was 720 lbs on the coupe. This means in an all-out corner, the inside tires are pretty lightly loaded (might be as light as 55 lbs!)
Now, how does this make a quad racer into a tricycle? First, front anti-roll bar is too stiff, or rear is too soft, but that's another discussion. Let's take it out of the illustration for now.
Besides this, at a corner exit, with the rear end planted well, in a hard corner, the following occurs:
1. Acceleration forces causes, let's say, 10% of cars weight to transfer to rear wheels off the front. That reduces front wheel loads from 775 to 697.5.
2. The cornering force transfers 720 lbs from the inside wheels to the outside wheels.
This would result in the following four corner weights in a hard right hand turn:
left front: 1395.5 lbs
right front: -22.5 lbs
left rear: 1572.5 lbs
right rear: 132.5 lbs
So, you have the right front wheel lifted off the ground.
This is still an over simplification, as it is a static snap-shot and does not include that some energy is directed laterally and does not actually result in tire loading as a virtical force suggested. However, the effect is essentially the same. Acceleration forces combined with cornering forces creates uneven wheel loading which, in severe cases, can result in one wheel lifting off the ground!
Now, look back at the numbers and think about something. Int his example of maximum forces and weight transfer in a corner, look how little weight is left on the inside wheels! This is why a car rolls over if it hits something like a curb when in this condition! That's why it's not such a great idea to get your car in this condition on public streets. Race tracks generally are surrounded by looses stuff, like gravel. The effect is, in a max corner condition, should you slip off the asphalt, the grip is radically reduced, the corner force is cut, as the car slides, transferring more weight on the inside wheels, reducing the tendancy to roll over (except on rare occassions where a tire grabs the softer material, which acts like a curb).
Anyway, the cae of the Coupe on three wheels was agreat addition to the discussion, Thanks dp!
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