The sideview angles of the...
The sideview angles of the upper and lower control arms determine the amount of antidive or prodive. The upper arm must be angled with the front higher than the rear, and the lowers must be angled with the rear higher than the front in order to have antidive. With prodive, the arms are positioned with the opposite angles.
3. CAMBER CHANGE
A car that is loose on entry to the corner can have several problems. If the car is severely loose and nothing seems to help, it is almost always rear-end alignment that is causing the problem. If the rear end is pointed to the right of the centerline of the car, it will tend to swing to the right as the car is steered left, much the same as a hook-and-ladder fire truck does when the guy in the back steers right going around a left-hand corner. The car will feel much the same as this.
Regardless of how straight you think the rear end is as this is happening, start moving the RR forward 11/48 inch at a time until the car is no longer loose-in. Most of the time, we don't have the facilities or the time to re-align the car at the racetrack. So we do this quick fix and later re-measure the car at the shop.
At racetracks with a tight entry and/or requiring heavy braking on entry, the loose condition could be brake bias or shock related. If you think the rear brakes are overwhelming the front brakes and making the car loose, try moving the brake bias to the front first. We usually need a front-to-rear percent ratio of 60:40 or 65:35 for most stock cars.
If that does not help, then decrease the rebound in the LR shock and/or increase the compression in the RF shock. A common fix to a car that was tight on entry used to be to increase the LR shock rebound rate to pull load off the LR corner as the car entered the turn. This would theoretically loosen the car. While that would probably help the situation, it is only a crutch. Look for the real problem first before taking drastic measures with your shocks.
When our moment center is...
When our moment center is located to the left of centerline, the moment arm is longer and the front end will tend to roll more. As we move the MC to the right, the moment arm will become shorter, and the front end will become stiffer and roll less.
4. MOMENT CENTER DESIGN
The front moment center location plays a huge role in the front end's tendencies. The MC should always be somewhere close to the centerline that is midway between the tire contact patches. The farther left the MC is located, the more efficient the front end will be and the more inclined it will be to roll. If the MC is farther to the right of the centerline, then the front end will be stiffer and less likely to roll. Low-banked tracks require a location more to the left and higher-banked tracks require a setup with a MC more to the right of centerline.
The center of gravity height also influences where the MC should be located. Cars with a lower CG should have a MC that ends up farther to the left side of the scale than that of cars with a higher CG.
We should divide the turn...
We should divide the turn into three phases or segments in order to analyze the handling. The middle phase is most important to overall track performance. Entry and exit performance helps us pass cars on the racetrack.
5. BASIC HANDLING PROBLEMS
A tight/loose condition is evident when a car appears to be loose when in fact it is tight. This condition is very hard to detect from a driver's perspective. The car feels loose right at midturn and off the corner. Sometimes the car is tight and the driver has to turn the steering wheel far enough to get the car to turn.
Because the front tires generate more traction with a greater angle of attack, the driver is actually putting more traction into the front end by turning the wheels. The once-tight condition now switches to loose as the front gains grip from excess steering angle. This happens very quickly and the rear end snaps loose as the throttle is applied. All the driver knows is that the car is loose. To correct this, we have to fix the tight condition so that less steering input is required. This malady is more common than most racers know.
Tight in the Middle-The Car Won't Turn
This is the A-one complaint for most ill-handling stock cars on dirt or asphalt. The problem usually is a result of the following: 1) poor front-end geometry, involving moment center location and steering geometry; 2) a rear end that is pointed to the left of centerline; and 3) the wrong choice of springs, weight distribution, and rear moment center height.