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      01-27-2014, 02:22 PM   #40
CanAutM3
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Quote:
Originally Posted by Boss330 View Post
This article explains some of the physics involved:

http://www.autospies.com/news/The-Ef...Moments-50856/
Quote:
Originally Posted by stefan View Post
I am really not sure of what advantage is gained from a 50/50 weight, after factoring suspension into the equation. I suppose your car balance will be easier to predict initially at a track particularly during minor weight transfers. But it's nothing you wouldn't just adapt to if it weren't perfectly split.
This article is full of flaws. It assumes that the path the car travels is linked to the mid point between the front and rear axles; since only the front wheels are steered, this simply isn't true (even on cars that have rear wheel steer, the fronts still do most of the steering). On rear weight biased car, the article concludes that the rear wheels need to cary more lateral load. This is correct, but since they also carry more normal (vertical) load, it becomes a moot point.

A car, as it travels through a bend, also needs to pivot on itself to keep the proper heading. The car does not pivot around its CG nor does it pivot around its "middle". The car pivots around the mid point between the two rear wheels (assuming zero slip angles). Imagine the front wheels steered at 90deg and this becomes very obvious.

To calculate the moment of inertia of an object pivoting around a point, the natural moment of inertia of the object needs to be added to the mass of the object times the square of the distance of its CG relative to the pivot point.

So the closer the CG is to the rear axle, the easier it is to pivot a vehicle. Hence the benefit of a rear weight bias.

The counter point is that when the rear tires start to slip more than the fronts (oversteer), the pivot point progressively moves away from the rear axle towards the front axle. So once you loose the back end on a rear weight biased car, it becomes much more difficult to bring it back.

Last edited by CanAutM3; 01-27-2014 at 02:45 PM..