Need help setting pinion angle.

[SinisterC10]

I am trying to figure out where my pinion angle needs to be. This is a leaf spring truck but I am running Cal-Tracs so I’m not sure how much those will factor into to determine the best angle. I know they will reduce the amount of spring wrap which in theory should help the pinion from wanting to raise under acceleration.

I cannot raise my transmission angle any higher than 86* because it will hit the transmission tunnel (Th400). Both my transmission and my pinion are setting at 4 degrees down (86*). I know the angles are suppose to be parallel but than that would mean that I would have to have my pinion angle at 4* up (94*) correct? I didn’t think the pinion was suppose to be pointed upward that much, so that’s where I’m getting confused.

[VileZambonie]

What are you using to measure pinion angle? With the transmission sitting normal, measure the angle with the truck on it's wheels on the ground. The difference in the angles is your pinion angle. I use the ford pinion angle gauge which works awesome.

[SinisterC10]

 I’m using a magnetic base analog angle finder. I have a digital angle finder to but I find that the analog needle style is more accurate. My truck is on my four post lift so everything is where it would be if it was sitting on the ground.

From what you said above that my pinion angle would be at 0 wouldn’t it? Since both my pinion and my transmission or pointing down 4°. In order for the imaginary lines going through the pinion and trans to be parallel and not crossing, I would have to have my pinion set 8* higher than it is now wouldn’t I?

https://goo.gl/images/SwJ7GB

I’m just really confused.

[VileZambonie]

You want close to equal angles under normal driving conditions to prevent driveline vibration. There is a lot of misinformation out there about pinion angles. Many don't know why pinion angle is important and I have seen a lot of incorrect driveline angles but the reality is what you are trying to accomplish is an equal input and output angle for constant velocity. I'm assuming you are using a one piece driveshaft with a slip yoke?

If the angle between the input yoke and driveshaft is equal to the angle between the driveshaft and pinion shaft the two non-constant velocities at each end of the driveshaft cancel each other out. The pinion shaft will turn at the same constant speed as the transmission shaft. A balanced driveshaft connecting the dots equals smooth sailing. So with a leaf spring suspension your static target measurement is typically -4° to -7°. I aim for -3° with the 4 link setup.

[VileZambonie]

Here is the tool I use T68P-4602-A

https://www.ebay.com/itm/FORD-ROTUNDA-OTC-TOOL-7009-SAME-AS-T68P-4602-A-PINION-ANGLE-LEVEL-GAUGE/323206934653?hash=item4b40a2707d:g:qusAAOSwYgFasWMf

[SinisterC10]

I ordered some shims from Summit. 6* and 8*. After I get a pair installed, I’ll go from there and let you guys know.