11. Pinion Angle Challenges
In the past, pinion angle has been measured relative to the ground. This approach does not represent the true picture of PA. What should be of concern is the angle of the driveshaft to both the pinion and the transmission output shaft.
When the U-joint operates with any amount of drive line angles, it has a problem. The bearings speed up and slow down twice per revolution of the driveshaft. This causes an oscillation in the powertrain. The more angles that we have, the higher the peaks of oscillation we see and therefore the greater chance of vibration.
Driveline angles are a cause of vibration and power loss. If your race car must have drive line angles from a design standpoint, the angle of the driveshaft to both the transmission output shaft and the pinion shaft should be equal and also opposite. The angles should be kept to a minimum when at all possible.
Driveshaft angles are not only measured from a side view, but also from a top view. Some offset late-model cars can have as much as a 11/2 inch displacement of the rear of the driveshaft from the front. That equals almost 2 degrees of driveshaft angle at both the transmission and the pinion. So, we can align the driveshaft, from a side view, to zero angle and still have 2 degrees of overall driveshaft angle present.
12. Alignment Challenges
Poor alignment can ruin an otherwise great setup. How critical is whole car alignment? It is very critical. Four-wheel alignment can be the final setup parameter that can take you to the front or keep you in the rear of the field.
The problem is that no amount of manipulating the other setup components will overcome a wheel alignment problem. While it is probably true that a car out of alignment is more forgiving on dirt, it is still very important for both dirt and asphalt to have your wheels properly aligned.
This whole process of aligning your race car should only take about an hour or two if there are several team members helping. That is very little effort expended to make sure your car will track correctly.