Here is a link to a video of my circle track car (metric 4 link) on our dyno to see and measure pinion wrap. First let me say that the shock is not bent. The lens on the gopro makes it look that way.
The 3" mark is the at rest zero. I know I should have marked it differently. Anyway, the rod is 12" long from the centerline of the axle to the black mark on the rod. Math: .209 inches per degree. so .5 inches of travel = 2.39 degrees at the maximum amount of wrap up travel seen. At the end of the video I make the long measured and recorded pull by the dyno. If you watch closely you can see the pinion wrap to max travel then slowly unwrap as it goes past peak power.
Different cars , traction , suspension types, horsepower levels and etc. are going to affect what the correct pinion angle is for your application.
