There are many names for the condition in which a race car turns too little or too much. So let's start with some definitions.
"Push," or "understeer," means the car doesn't want to follow its steered direction. Therefore, it is said to be pushing away from the steered direction. The opposite of a push is when the car's front tires stick to the track and go in the steered direction.
"Oversteer" is another name for "loose." Loose is the term for the rear end wanting to pull around and turn the car sideways in a corner. The opposite of loose is "tight." Tight refers to having the rear of the race car sticking too tightly to the tracks made by the front.
PushFirst, let's tackle push. When a race car enters a corner, the steering wheel is turned in the direction the driver wants to go. If the traction available is sufficient, the front end is said to stick. Thus, the front end of the car follows the steered direction.
When the front tires do not have enough traction to overcome the straight-line inertia of the car, they skid across the track. The tires are pointing into the turn but the car is in less of a turn. Here the car may turn somewhat but not enough to negotiate the turn quickly.
A push on corner entry is much the same as applying the brakes-the tires are sliding. The immediate cure for this is to slow the car until traction overcomes inertia. Now the car will follow the steered direction, but speed has been lost.
The simple cure for a push is to add weight to the right front, creating more traction. There are many things that contribute to front traction: springs, shocks, caster, camber, to name a few. However, given that the rest of the suspension is somewhat close to correct, weight must be added to the right front.
I am not suggesting 11/42-inch thick lead fenders. The weight must be shifted from one corner to another. To do this, the right front will be raised in comparison to the left. If the car has weight jacks, then simply screw down on the jack. Keep doing so until the push goes away. Without weight jacks, use a smaller left front tire or larger right front. Keep in mind, there can be too much of a good thing. Every adjustment on a race car is a compromise.
I have often seen a push misdiagnosed. In a severe case, the car pushes, slows down and grabs a handful of traction. When power is applied, the rear spins around and the driver is looking at where he has been. Often the driver says the car is loose.
Corner problems must be solved in the order in which they are received. In other words, a problem on corner exit cannot be solved until any problem on corner entry is corrected. In the preceding example, the problem was not the car wanting to spin out. Instead it was the push that led to spin out.
Push can also be a problem on corner exit. Here, with power on, the car drives outward toward the wall. Right-front weight will have little effect in this case. In this scenario, the push is caused by the rear of the car. The rear, with power, has more traction than the front, so the rear wheels direct the car. When the right-rear tire is larger than the left, it is called "stagger." Add stagger, i.e. a smaller left rear, when the rear drives the car toward the wall on corner exit.
This difference creates a tendency for the rear to turn. The classic example is the foam coffee cup. It has a larger diameter on one end and a smaller on the other. Laid on its side and given a shove, it will roll in a circle. This is how rear tire stagger works.
Loose, TightSimply stated, loose is the condition where the rear wants to run outside the tracks of the front. In a severe loose condition, the car will spin out easily. Conversely, a small amount of loose is often beneficial to speed. This allows a driver to balance power and traction with his throttle foot. This is especially true on dirt.