How to Test the Track
If you have made some changes to the car you will need to do the track testing to see how these changes will work. The objective of the testing is to find an ideal setup combination that will be not only initially fast but will also remain fast for extended period time. The setup must be good on the tires, comfortable for the driver, and beat the competition. For dirt, certain setup changes will have to be made for the different track conditions.
Pre-testing Preparation and Planning
It is vital to know your car well before you actually start testing. If you are going to test on a new track, you must take into account the banking and transitions. High banked tracks require higher spring rates but if the track is flatter, think how you are going to bite off the corners.
Once you get to the track, choose a pitting position for your vehicle that is relatively level. Make sure there is an easy access to the tool cart, the trailer and other track facilities. It is also necessary to park the car in the same spot after each run so you will need to mark the ground around the tires. Consider weighing the car before and after the testing to find out how different adjustments influenced the weight distribution of the car.
Measuring Track Performance
To measure the on-track performance of your car focus on speed, the motor/gear, and the chassis setup combination. In case you test them separately, you will need to measure them separately as well. To figure out the condition of the chassis setup make sure you analyze turn segment times. By improving the mid-turn speeds, you will increase the straightaway speeds.
The First Set of Runs
It is recommended to start the testing with making several slower circuits followed by a few faster laps. Consider doing at least two short runs after the first time out to get meaningful tire temperatures. The driver should first run the turns at a speed lower than normal and notice the position of the hands. If the hand position differs a lot at the higher speed it means that the car is either tight or loose. After each run, you need to record such data as oil temperature, engine water, tire pressures and temperatures, tire sizes, etc. Once you make sure that the car is OK you may try doing longer and faster runs.
The tire cambers, pressures and overall handling balance need to be evaluated. Consider making quick adjustments to the front tire cambers and all four tire pressures if necessary. Keep in mind that chassis adjustments can be made only after you have dealt with the tires.
Ask what the driver and the crew think about the car handling and engine performance. If needed make adjustments to improve the handling and try to maintain a balanced setup. Handling Balance differs from Dynamic Balance. The car is considered to be neutral when it is neither tight nor loose. Your goal is the car which is both neutral in handling and balanced in how the front and rear suspension are working.
Mid-Turn Performance First
First of all you should evaluate and correct the mid-turn performance. The tire temperatures can be the indicator of the car balance. They show how much work each tire is doing in relation to other tires. Your goal is to get equal temperatures on pairs of tires on each side of the car.
If the tire is too cool adjusting panhard bar height and/or spring rates can help. If front tire temperatures are uneven it means a tight car while high RR tire temps mean a loose car. When the tire temps become equal on each side, you can tune the handling balance with cross weight.
The best way to re-balance a circle track car is to make a spring split in the rear and change panhard bar height in addition to tuning the handling with changes in cross weight.
Rear alignment issues or incorrect shock rates, primarily in the LR corners of the car, account for most entry problems. Over-driving the entry may often result in a car push. The rear end must align properly and square to the centerline of the car. Remember not to install a high rebound left rear shock.
Because of excess LR shock rebound the car can become loose on entry. Ideally the LR shock should let the LR tire move in rebound.
Spring split also impacts entry performance. A stiffer LF spring over the RF spring often ensures entry stability on a flatter track. In addition, spring changes influence the Dynamic Balance of the car as well so make sure you re-evaluate the tire temperatures and adjust the panhard bar to re-balance the setup each time a spring is changed.
Tight-off or loose-off condition leads to problems with corner exit. Keep in mind that all changes made with the purpose of enhancing exit performance should not affect the mid-turn balance. Changing spring rates, spring split, panhard bar height and cross weight will not help but can destroy mid-turn balance instead. To tune exit performance you need to increase the amount of grip the rear tires have available on exit without affecting the mid-turn balance.
The End of the Test
It is necessary to save your sticker tires for the last runs of the day of testing. If you are happy with the setup, you can put on fresh tires and make a qualifying run on them, followed by a 30 or 40 lap run to check whether the lap times remain consistent. If the setup is balanced well you will get lap times that fall off less than those of your rivals. During the testing you can confront with such challenges as incorrect tire stagger, bent shocks, suspension binding or poor alignment. If setup adjustment does not help it means that there must be a mechanical problem with the car so you should discover it and fix it.
Review your test notes from time to time and try to test the car as often as possible. Before the testing develop a comprehensive plan and stick to it. This will help improve your performance so you could enjoy a truly exciting racing experience.