Here is the article that is at the link I provided. (http://craig.backfire.ca/pages/autos/cutting-springs)

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Introduction

Lowering a car is a common practice when trying to improve the handling or the appearance. In some cases, this is done by cutting the springs that came with the car. In this article, I will be looking at the problems caused by using cut springs.

How Springs Work

A spring is a mechanical device that absorbs energy by deflecting a certain distance. Springs have a property called a spring constant which is a ratio of the force applied to the deflection distance. A higher spring constant implies that the spring will have a lower deflection distance for a given applied force.
The magnitude of the force and the spring constant determines the compression distance of the spring.

When the tire of a car goes over a bump, an upward force is sent through the suspension to the springs. The springs will absorb the energy by deflecting by a certain distance, depending on the value of the spring constant and the magnitude of the force from the bump.
Bottoming Out

Due to packaging and other contraints, a car's suspension can only travel so much before bottoming out. When this happens, the spring will no longer absorb any more energy from the bump, and the remaining energy will be sent to the chassis and passengers. This is an unavoidable condition, which is why cars are designed to handle a reasonable amount of force being transmitted to the chassis.
The force that the chassis will receive from the bump is equal to the force of the bump minus the force taken by the spring.

Lowering a Car

The springs play a key role in the car's ride height. The weight of the car itself places a force on the springs, which deflect until all of the force from the weight has been absorbed. At this point, the spring is said to be in equilibrium, and the car will be resting at its ride height.
Lowering a car is as simple as fitting springs which will have a lower total height when the weight of the car is placed upon them. There are two main approaches which can be taken to achieve a different spring height, one is to cut the springs which came with the vehicle, and the other is to replace them with lowering springs.
A lowering spring will be shorter than a stock spring when unloaded, and will have a higher (stiffer) spring constant as well.
A cut stock spring will also be shorter (obviously), but unlike the lowering spring, it will have a spring constant which is basically the same as the stock spring did. However, if the spring was cut using a method which caused the spring to heat up significantly, the spring constant may actually be lower than before it was cut.
Suspension Travel and Chassis Load

A lowered car will have less suspension travel before bottoming out. Because of this, the spring must absorb the same amount of force as the stock spring, but in a shorter distance. This implies that a spring with a higher spring constant must be fitted.
In the example below, the stock spring has a resting loaded height of 10 inches. The car will be lowered 2 inches, using either a stock spring which has been cut or a lowering spring. With the stock spring, the suspension has 4 inches of travel before bottoming out.
Comparison of the three springs.

If the suspension at stock ride height has 4 inches of travel, and the stock spring has a constant of 100 lb/in, then the spring will absorb up to 400 lb of force before the suspension bottoms out.
If the stock spring is then cut so that the resting height is the desired 2 inches lower, then there is 2 inches of suspension travel left. The spring constant is unchanged, so the spring can absorb only 200 lb of force before the suspension bottoms out.
If a 2 inch lowering spring with a spring constant of 200 lb/in is fitted, the spring will be able to absorb 400 lb/in before the suspension bottoms out, as was the case with the stock spring.
Below is a diagram showing the three springs when the suspension has bottomed out.

The cut stock spring takes only 200lb to bottom out, while the stock spring and lowering spring takes 400lb.