Pinion Angle

[41Chevy]

I just want to double check my readings. Measuring off the harmonic balancer I get 86* tailshaft tilted down. Face of pinion 90*. Is this -4 degrees pinion angle ?

[Mike Thompson]

Its supposed to be the difference between the drive shaft angle and pinion yoke angle.

Some people say no its the difference between the pinion yoke and a level surface. I never understood that one. After all you are trying to get a small amount of angle to keep the u-joint alive and moving. Nothing more IMO.