Disagree with Pinion Angle Info in latest GS X-tra ?

[CS99]

The article says pinion angle is the difference between angle of transmission and pinion. I think "Pinion Angle" is the angle of the drive shaft to the pinion. Anyone else have any input?

 

[toofastforyou]

I think YOU're right...

Claude.

 

[bison]

The pinion angle info by itself is not enough info. Both angles need to be added together to get the driveshaft angle. So it's not the difference. They should cancel each other out.

 

[KevinB]

You can use the trans or the driveshaft or the crank center line to measure the difference of the pinion so I think you both are correct

 

[charlief1]

Might want to visit baseline suspension for how to figure it out. Kevin has a reall goo site some som calculators on how to figure out what you need to know.

 

[Slow91z]

Go over to yellowbullet and you will see that this is something that apparently no one can agree on...pages and pages of reading on this subject.

 

[SHADOWII]

You can use the trans or the driveshaft or the crank center line to measure the difference of the pinion so I think you both are correct

So the definition is determined by your goal.

 

[Pronto]

Here's the Baseline link. Good info there. http://www.baselinesuspensions.com/info/pinionangle.htm

 

[KevinB]

In the end, driveshaft, trans, or center line of crank will get you the same measurement. I always use the driveshaft method because its easiest.
If you go to the baseline website, buy Kevin's rearend package. You will not be sorry

 

[Blazer406]

It is clear in my mind...... you want the driveshaft to be in perfect alignment with the pinion while under load. The critical part is how the u-joint behaves when misaligned. The torque output is not linear when misaligned..... it has small humps in the torque output going to the rear end...... like a sine wave..... or evenly spaced ocean waves (closest real world thing I could think of to help visualize) ..... the larger the mis-alignment... the taller the ocean wave..... and deeper the trough between the ocean wave. If you have perfect alignment, you'd theoretically have no waves..... calm, flat as glass water.... like a lake with no wind.

I think the body of the driveshaft is a good reference for one measurement.... I think the jury is still out on the rear end. I'm not convinced the cast iron flat spot underneath the pinion is the same angle as the pinion. You could measure the driveshaft angle, then remove the driveshaft and use the yoke cap itself which would be an indicator of proper alignement.... of course if you did that, perfect alignement would be 90° difference.

In theory, there is a certain amount of slop or flex in the bushings and pins in the rear control arms..... so you typically want the pinion angle to be where the snout of the rear end where the pinion sticks out to be a few degrees (3° down is a good start) down from a perfect alignment.... this lets the torque applied get all the slop out as the pinion tries to rotate up toward the floorboard during acceleration. If you did everything right, it should align up perfectly during a run.

Hopefully this helps.....

 

[KevinB]

I always put a socket on the ujoint cap at the rearend to get the flattest spot.