Quote:

2° trans down and 2° pinion up is parallel and the relative pinion angle would be 0° under load...Not 2° nose up which is what I think some of these guys are interpreting it as...drive shaft angle is irrelevant as u-joint angle will be equal and opposite at both joints.



If you lower the trans yoke by lowering the front of the car or put a big tire on it and raise the rear end up into the chassis, the pinion angle (difference between driveshaft and pinion angles) will quickly go positive at some point, if parallel is the only thing taken into consideration. Imagine moving the centerline of one of the yokes up or down while the other remains stationary. What will that do to the operating angles, parallel or not?

I agree, having the trans and pinion centerlines parallel or close to it is beneficial and can be accomplished with engine/trans location. However, pinion angle, the relationship between the d-shaft and the pinion, has to remain correct according to the type of suspension and never go positive. It is a setting, not an adjustment.

It's not that one's right and one's wrong. Both matter, but one is most important and has to be right.

If the results don't match the theory, change the theory.