The correct stagger you will...
The correct stagger you will need for a particular track is fixed and not to be used as a tuning tool. We never want to adjust stagger to mask a handling problem. Using incorrect stagger is a crutch and will only provide a temporary solution. Running the wrong stagger can cause a multitude of handling problems.
• Softening the front springs will help the car turn, but to a lesser degree than making rear spring changes. Spring split at the front also has less affect and has more influence on entry characteristics than on mid-turn. More on that later.
• Installing larger or smaller sway bars will have an effect on handling. The stiffer the bar, the less the front will want to turn. So, to help cure a tight car, we can go to a softer sway bar.
• Increase or decrease the crossweight percent. As we make changes to the crossweight, we affect the handling of the car and we can easily make the car neutral in handling by making crossweight changes. But, this is not the ideal method by any means; it's just the easiest.
• The reason this method is not ideal is because for every car and combination of springs and weight distribution, there is an ideal crossweight that matches up with a dynamically balanced setup and is related to the front-to-rear weight percentage. If we knew this magic number, we could just dial it in and then make spring or moment center changes until the car was neutral and then everything would be just right.
Rear end alignment and the...
Rear end alignment and the use of roll and squat steer can enhance exit performance. We never want to cause rear steer to the right on asphalt, but on dirt we may use rear steer to the right through mid-turn and then utilize squat steer or power-induced rear steer to the left to tighten the car off the corner.
• Increase or decrease stagger? This is never an acceptable way to tune the handling of your race car. For every turn, there is an ideal stagger that will allow the car's rear wheels to roll around the radius and not influence the direction the car travels from following that radius. Learn what stagger your track needs or use our free calculator offered on www.circletrack.com under the MultiMedia section.
Once we have set up the car to be neutral in both handling and dynamic balance, we need to evaluate the entry handling. If our entry is without issues, meaning it is straight ahead, not tight or loose, and no excess steering input is needed beyond the normal transition from straight to left turn, then we are good to go.
If all of the alignment issues have been sorted out, there should never be entry problems, but there are influences that could affect entry stability and balance. Here are the top ones to consider.
• A. Rear alignment is the number one cause of entry problems Either by misalignment of the rear tires or by rear steering of the rear end, a car can become tight or loose on entry and that can translate to mid-turn problems. The truth is, you should have checked and corrected any rear alignment problems long before you came to the track. Rear alignment and rear steer are not tuning tools.
Rear suspension links can...
Rear suspension links can be arranged to provide many different degrees of rear steer, or zero rear steer through chassis roll and squat. You can duplicate what is happening on the track by supporting the chassis on stands and then moving the rear wheels vertically and measuring the amount of movement fore and aft of each rear wheel. This is an important exercise and can help you better understand your rear end alignment issues.
• B. Shocks affect entry
Shock rates that restrict movement of one or more corners of the car can negatively affect entry. A LR tie-down shock will help cure a tight-in condition by loosening the rear, but this is only a crutch.
The two corners most affected by the dynamics of corner entry are the LR corner and the RF corner. A RF shock that is stiff on compression can cause a tight condition on entry and a LR shock that is stiff in rebound can cause a loose condition on entry.
• C. Brake bias changes affect corner entry There is an ideal brake bias that will allow maximum braking of each set of tires based on the loads those tires carry. Different cars with different centers of gravity will require different brake bias.
Tune your brakes so that wheel lockup occurs simultaneously at the two ends of the car under heavy braking. We do not want the brake bias to influence entry handling characteristics. Never try to correct a tight car by increasing the rear brake bias or fix a loose-in car by increasing front brake bias.
To test your bias settings, try this exercise. Try entering the corner with sufficient speed and with a soft application of the brakes and feel the entry balance. If good, proceed to the next step. If not, refer to steps A. through C. above. Once the car is neutral without heavy braking, then enter the corner at speed with the normal brake pressure that would be used in the race or in hot laps and see if the handling changes. If so, tune the brake bias to be neutral.