Air shocks and Pinon Angle.

[Crazy4408pac]

A buddy of mine, has a big block, 1970 Dart Swinger. He has air shocks because he likes jacking it up 70s style then lowering back down to normal ride height.

Asked me if using the air shocks messed with the pinon angle. I told him that I didn't think so, but said I'd get some other opinions.

What ya think?

 

[Darter6]

Yes.As the body rises so does the transmission tail shaft, changing the pinion angle. The rear remains the same. Now this is the extreme. A rise of 1-2 inches in the rear shouldn't cause a problem.

 

[67Dart273]

Yup.

 

[pishta]

not as much as you would think...the trans does go up but the pinion angle is the difference between the output shaft and the yoke. If you drop the rear down with equal length springs and risers on all 4 points it will stay in the same relative plane as it was when it was normal drive height, BUT none have equal length spring with all being longer in the back, as well as the shackles in the rear so your pinion nose will swing up in relation to the output shaft. Upon acceleration it will wrap up opposite the wheels so it will be even more "positive". Not real good. Generally you want a little negative pinion (down) at rest, maybe 2-3 degrees.