To easily understand the term loose, push a small toy car with a pencil and make it turn a corner. It turned sideways very easily because it is loose.
A car can be loose on corner entry. Braking or slowing will tend to make it go sideways. This means the car must be slowed to a greater extent to enter the corner safely. Stagger has little effect with the power off. Corner entry speed is critical. It sets the speed for the rest of the corner. If the car is too loose or has a push entering a corner, the resulting need to slow down will make the speed on the next straight slower, too.
The first thing this car needs is to be tightened up on corner entry. We can dial in some right-rear weight with a jack screw. Remember, it is all a compromise. It is possible to get the car jacked all out of shape, so go easy. Note how many turns up or down are made so you can return to the original settings if needed.
Other things affecting a loose-on-entry condition are brakes and springs. If the rear has too much braking force over the front this can be a problem. If you have an adjustable brake bias setup, then dial in more front brakes. The rear tires here are using their traction to slow down, thus their sideways traction is limited. If the right rear spring is too strong, the chassis won't roll over and transfer weight to the right rear. Excess wheel offset can cause the problem too. Tucking the wheel back closer to the chassis has the effect of adding weight to that corner.
If the car is loose on corner exit we have another set of circumstances. In this case, when power is applied, the car wants to go sideways. A small amount of this is beneficial. Theoretically, a neutral-handling car would be best. But the track is never the same in any two corners, much less from hour to hour. Remember, a push scrubs off speed but a bit of loose lets a driver drive with the throttle, power on.
The easiest way to make changes to a loose-coming-out condition is with stagger. Too much stagger causes the right rear to swing around. Zero stagger tends to drive the car the way it was pointed when the power was applied. This happens whether you are out of the corner or not. The right amount of stagger for the moment allows all the power to be applied and the car to be kept under control. Sometimes you will need to change stagger several times throughout the race program as the track changes.
I have run across a few occasions where a driver has used reverse stagger (larger on the left). His car worked OK, but I believe some other part of the suspension was crippled and this was a patch. A man can run pretty well on crutches if he has enough practice.
Some classes, notably IMCA cars, use the same tire on all four corners. There is a size difference, but it is only slight. Here, things other than stagger must be used to loosen up the car. The right-rear spring can be lighter than the left. Thus, the car rolls over due to centrifugal force and loads the right-rear tire. Since it is the outside tire in the turn, it will have more traction than the left, where the weight is being unloaded. This pulls the rear of the car to the right. Wheel offsets can have some effect on this, too. In classes where it is allowed, suspension modifications play a large part in loosening the car up.
SummaryTo be fast, a race car must be balanced at the right point between push and loose. Imagine this point to be in an envelope: The better the driver, the larger the envelope can be, without affecting the speed of the car. It is difficult to achieve this balance consistently. Also there is no perfect setup that works all the time. A car that is right for the moment makes a driver look good.
Trouble In Aisle 2!A shopping cart experiment gives you an idea of loose and tight.
Welcome to Sleepy's Grocery Cart Driving School. This may sound odd, but the results are real. You can get the feel for the way a race car handles by going around corners at the supermarket.