[DML] Re: DeLoreans (like you hadn't guessed!)

[William T Wilson <fluffy@xxxx>]

On Thu, 24 Feb 2000, Robert Rooney wrote:

> Some of the spoilers do look nice on the D, but it would probably be
> best not to install one. A spoilers job is to place more down force on
> the rear end of the car. On a car with a front mounted engine, AND rear

There are two kinds of spoilers - rear wings, and spoilers. A rear wing
is a tall structure - like that used on many race cars, or late-model
Mitsubishi Eclipses or Toyota Supras, which actually works like an
aircraft wing and provides downforce. (though the Eclipse wing, I
believe, doesn't actually provide any downforce :} )

A spoiler, on the other hand, is there to create turbulence and break up
airflow. This counteracts the natural effects of lift created by most car
bodies. Lift can only be created by smooth airflow, so if your spoiler
counteracts this, it eliminates the problem of lift. Lift (the same thing
that holds up an airplane) reduces cornering grip and stability at high
speed.

A spoiler is not necessary on a DeLorean. The louvers break up the
airflow in the same way that a spoiler would. So though a spoiler may
give the car an aggressive look, it doesn't really accomplish anything.

> drive car, they will do nothing, but on a DeLorean (rear to mid-engine
> cars), I would imagine that by placing more force on the back, it could
> possibly give the effect of even worse weight distibution, thus making

Not at all. In fact, downforce on the rear would actually improve the
car's handling. Here's how it works:

The tendency of a rear engined car to swap ends is basically because the
heavy end likes to be in front. This is not a problem with just DeLoreans
- Porsches, MR-2s, and most other cars with rear biased weight
distribution are the same way. To compensate for this tendency, it is
necessary to apply more grip to the rear end. Suppose, with driver, fuel,
and everything else, your DeLorean weighs 3000 pounds, 2000 of which are
on the rear and 1000 of which are on the front. If you were swinging the
DeLorean around on a string attached to the middle of the car, the rear
end would swing out, because it's heavier and requires more force to keep
it turning. This is the natural tendency of a rear engined car to
oversteer and spin.

To balance this, you have to have more grip on the rear, to hold it firmly
to the ground. It has to provide twice as much cornering force as the
front. This is accomplished by the wide tires on the back, and the design
of the suspension, and by the weight of the car itself pushing down on the
tires, which increases friction with the road. Just as it's harder to
pull a sheet of paper out from under a stack of books than to pull it out
from under a single book, extra weight on the rear of the car helps
increase the friction of the tires with the road and thus, provide more
cornering grip.

If you had more downforce on the rear, it would be like pushing down on
top of that stack of books. Pulling the paper out from underneath becomes
even harder than before. That means more friction, and more cornering
force - and less chance of a spin.