Pinion angle for a street cruiser

[Siksty7 Dart 270]

I'm not belittling the wealth of information available from the experienced mechanics on this site related to pinion angle, but I found it to be a little overwhelming. Admittedly, I was confused by some of it and I set up my pinion angle on an 8-3/4 swap wrong on the first try. After consulting with a very friendly driveline shop, I made changes and found success. You'll see the explanation in the diagram attached. Please excuse the artwork.

 

[HemiDenny]

To eliminate vibration, it is important match the total amount of U-joint angles of the front u-joint and / rear u-joint

example....

1) differential angled DOWN 3.5 degrees MINUS (same angle) driveshaft DOWN 1.0 .................equals total 2.5 degrees

2) engine angled DOWN 1.5 degrees PLUS (opposite angle) driveshaft angled UP 1.0 degree......equals total 2.5 degrees

when the angles match, smooth as silk. stay away from a straight line / no angles

 

[Siksty7 Dart 270]

To eliminate vibration, it is important match the total amount of U-joint angles of the front u-joint and / rear u-joint

example....

1) differential angled DOWN 3.5 degrees MINUS (same angle) driveshaft DOWN 1.0 .................equals total 2.5 degrees

2) engine angled DOWN 1.5 degrees PLUS (opposite angle) driveshaft angled UP 1.0 degree......equals total 2.5 degrees

when the angles match, smooth as silk. stay away from a straight line / no angles

Thank you HemiDenny. Can you confirm what you mean by "differential angled DOWN". Does that mean the pinion center line is higher at the front or back? I think that's something that confused me on other posts I read. Is it accurate to say that in your example, it's a continuous down hill slope from the front of the crankshaft all the way to the pinion gear?

 

[oldkimmer]

Your trans tail shaft let’s say is level:0*. U want the front of the pinion down about 2-3 *. So at minus 2* at least. Yes the pinion yoke will be slightly down. Ever have the pinion higher than the tail housing. Kim

 

[Bewy]

Having a zero angle will cause rapid U joint wear because there is no relative movement of the U joint components & all the wear is concentrated in one section.