Quote:

Something came to mind. Transmission down 2.5°, pinion up 2.5°: on acceleration, won't the rear end want to climb (rotate) up more than 2.5°? And while driving, with the rear wheels propelling the car forward won't the pinion be up more than 2.5°? Will that cause a problem? Or am I over thinking this?

Edit: 340Shorty said what I've heard too. That's why I was wondering...

Under hard acceleration the pinion will want to climb the ring gear initially, yes but the rear is secured to the springs which will resist the action. As mentioned, under braking it's just the opposite. Under normal driving the rear will naturally pivot a little but the fact that it's bolted to the springs holds it true for the most part. Because the axle will naturally go up and down, the angles will always be changing slightly, but the initial setup is a good compromise. With leaf spring rears, traction bars are used to keep the springs from wrapping up due to the ring gear climbing which also helps to keep the pinion angle in check. For high horsepower drag cars that spend all of their meaningful time under hard acceleration, the setup will be different. The idea for a street car is to have the optimum angles for the most time as possible. With a four link, ladder bar setup or similar it's not an issue because the rear is held fast to a certain angle by the radius rods/ladder bar. In that case the pinion angle only changes when the whole axle assembly pivots up and down on the front rod mounting points, but the change is minimal in most cases.