I hate to admit this, but I have NO CLUE what in the world it's used for, or what it helps.

What is it set at stock? What does it need to be, and why is that better than stock? How do you measure it?

 

modular depot has some good info on this but basically you want some negative pinion angle for drag racing, the amount needed is dependant on the type of bushing you have. With negative pinion angle the driveshaft and the nose of the rearend both point down a little (like a slight V). When you launch the interia will cause the nose of the rear end to turn upwards thus pushing the rear tires down to prevent squat. Do this take your left and right hads and put you finger tips together, now make a slight V with them (finger tips pointing down). Now Zach this is a must... make the noise with your mouth of you revving to launch (if you have a 2 step, try to duplicate that noise), now do the noise of the clutch drop, at that moment move your finger tips upwards and pretend your right wrist is the back tire.

 

&lt\\;a href=&quot\\;http://www.wolferacecraft.com/pinion...spx%3C&quot\\; target=&quot\\;_blank&quot\\;&gt\\;http://www.wolferacecraft.com/pinion...\\;br&gt\\;for some reason this site is acting screwy and 1/2 the carp I type or copy &amp\\;amp\\; pates doesn’t turn out right. So the link above doesn’t show, nor will probably any other link I paste.&lt\\;br&gt\\;

 

&lt\\;FONT face=&quot\\;Courier New&quot\\;&gt\\;Myth #1: The pinion angle somehow affects how much traction the car &lt\\;BR&gt\\;will achieve.&lt\\;BR&gt\\;&lt\\;BR&gt\\;Straight Scoop: No way. The pinion angle doesn’t mean squat as far &lt\\;BR&gt\\;as the rear suspension is concerned. Think about it: why would the &lt\\;BR&gt\\;suspension care about u-joint angles? What determines the &quot\\;hit&quot\\; on &lt\\;BR&gt\\;the rear tires and the rate and amount of weight transfer is the &lt\\;BR&gt\\;intersect point of the upper and lower rear bars (control arms). &lt\\;BR&gt\\;That’s known as the &quot\\;instant center&quot\\; (IC), and combined with weight &lt\\;BR&gt\\;distribution, spring rates, and shock valving is what affects &lt\\;BR&gt\\;traction.&lt\\;BR&gt\\;&lt\\;BR&gt\\ ;Myth #2: You increased the pinion angle and the result was increased &lt\\;BR&gt\\;traction, so Myth #1 must be correct.&lt\\;BR&gt\\;&lt\\;BR&gt\\;Straight Scoop: You haven’t been listening. Pinion angle doesn’t &lt\\;BR&gt\\;affect traction. What happened is you shortened the length of the &lt\\;BR&gt\\;upper bars and that changed the intersect point, moving the IC &lt\\;BR&gt\\;farther forward. You also screwed up the pinion angle in the &lt\\;BR&gt\\;process. If you want to change the length of the upper or lower &lt\\;BR&gt\\;bars, or change their mounting points, that’s fine. But after you’re &lt\\;BR&gt\\;done you’ve got to go back and check and properly reset the pinion &lt\\;BR&gt\\;angle.&lt\\;BR&gt\\;&lt\\;BR&gt\\;My th #3: The garage floor is the correct reference point for &lt\\;BR&gt\\;measuring the pinion angle.&lt\\;BR&gt\\;&lt\\;BR&gt\\;Straight Scoop: You’ve got to be kidding, right? The garage floor &lt\\;BR&gt\\;doesn’t have anything to do with anything. What’s important is the &lt\\;BR&gt\\;drivetrain angle. It so happens that professionally built racecars &lt\\;BR&gt\\;are constructed so that the crankshaft is parallel to the floor, &lt\\;BR&gt\\;meaning that the transmission output shaft will also be parallel to &lt\\;BR&gt\\;the floor. But this usually doesn’t hold true for cars using a &lt\\;BR&gt\\;factory chassis. In most of those cases the engine is tipped &lt\\;BR&gt\\;rearward. Take a look under the hood of your Buick and you’ll see &lt\\;BR&gt\\;what I mean. The drivetrain angle is the reference point and is &lt\\;BR&gt\\;considered to be zero.&lt\\;BR&gt\\;&lt\\;BR&gt\\;How to Measure It: The best way to do this is with the car supported &lt\\;BR&gt\\;on jackstands, with stands under the front control arms and rear axle &lt\\;BR&gt\\;tubes, with the full weight of the car resting on the stands. Next, &lt\\;BR&gt\\;it’s best to remove the driveshaft. Using an angle finder (these are &lt\\;BR&gt\\;available from Competition Engineering or at Sears Hardware stores&lt\\;BR&gt\\;they’re a commonly used carpenters tool), measure across the surface &lt\\;BR&gt\\;of the rear transmission seal vertically(see illustration 1). This &lt\\;BR&gt\\;surface is perpendicular to the output shaft of the trans, so &lt\\;BR&gt\\;subtract the measurement from 90 to get the drivetrain angle. Let’s &lt\\;BR&gt\\;say that the measurement is -2 degrees(pointed down). That is our &lt\\;BR&gt\\;reference point. Look at illustration #3. The pinion angle is the &lt\\;BR&gt\\;difference in the angle of the rearend to the angle of the &lt\\;BR&gt\\;drivetrain. So, in order to have zero pinion angle, the rearend &lt\\;BR&gt\\;would have to be tipped upward (pinion yoke pointing upward) 2 &lt\\;BR&gt\\;degrees. If our drivetrain angle measured -5 degrees, we’d have to &lt\\;BR&gt\\;tip the rearend upward 5 degrees to have zero pinion angle. Get it? &lt\\;BR&gt\\;Now turn the pinion yoke so that the u-joint cups are sideways, and &lt\\;BR&gt\\;measure across one side of the pinion yoke vertically(see &lt\\;BR&gt\\;illustration 1) where the u-joint strap connects. Again, this &lt\\;BR&gt\\;surface is perpendicular to the pinion, so subtract the measurement &lt\\;BR&gt\\;from 90 to get the rearend angle. compare this number to the &lt\\;BR&gt\\;drivetrain angle to get the pinion angle. If the drivetrain angle &lt\\;BR&gt\\;was -2 degrees(pointed down), and the rearend angle measured +1 &lt\\;BR&gt\\;degrees(pointed up), then the pinion angle would be -1 degree. If &lt\\;BR&gt\\;the drivetrain angle had measured -2 degrees (pointed down) and the &lt\\;BR&gt\\;rearend angle had measured -3 degrees (pointed down) then the pinion &lt\\;BR&gt\\;angle would be -5 degrees. In my particular case, the drivetrain &lt\\;BR&gt\\;angle measured -4 degrees, and the rearend angle measured -6 degrees, &lt\\;BR&gt\\;resulting in a pinion angle of -10 degrees, a wasted tailshaft &lt\\;BR&gt\\;bushing, and a slower than necessary racecar. The idea is to have &lt\\;BR&gt\\;the pinion angle at zero with the racecar under power and going down &lt\\;BR&gt\\;the track. To allow for suspension movement and loading, the pinion &lt\\;BR&gt\\;angle should be at around -2 degrees for our cars. &lt\\;/FONT&gt\\;
&lt\\;P&gt\\;
&lt\\;CENTER&gt\\;&lt\\;TT&gt\\;Illustration 1&lt\\;/TT&gt\\;&lt\\;/CENTER&gt\\;
&lt\\;P&gt\\;&lt\\;/P&gt\\;
&lt\\;P&gt\\;
&lt\\;CENTER&gt\\;&lt\\;IMG src=&quot\\;http://buickperformance.com/pinionangle1.jpg&quot\\; align=bottom&gt\\;&lt\\;/CENTER&gt\\;
&lt\\;P&gt\\;&lt\\;/P&gt\\;
&lt\\;P&gt\\;
&lt\\;CENTER&gt\\;&lt\\;TT&gt\\;Illustration 2&lt\\;/TT&gt\\;&lt\\;/CENTER&gt\\;
&lt\\;P&gt\\;&lt\\;/P&gt\\;
&lt\\;P&gt\\;
&lt\\;CENTER&gt\\;&lt\\;IMG src=&quot\\;http://buickperformance.com/pinionangle2.JPG&quot\\; align=bottom&gt\\;&lt\\;/CENTER&gt\\;
&lt\\;P&gt\\;&lt\\;/P&gt\\;
&lt\\;P&gt\\;
&lt\\;CENTER&gt\\;&lt\\;TT&gt\\;Illustration 3&lt\\;/TT&gt\\;&lt\\;/CENTER&gt\\;
&lt\\;P&gt\\;&lt\\;/P&gt\\;
&lt\\;P&gt\\;
&lt\\;CENTER&gt\\;&lt\\;IMG src=&quot\\;http://buickperformance.com/pinionangle3.JPG&quot\\; align=bottom&gt\\;&lt\\;BR&gt\\;&lt\\;BR&gt\\;&lt\ \;/CENTER&gt\\;
&lt\\;P&gt\\;&lt\\;/P&gt\\;
&lt\\;P&gt\\;&lt\\;TT&gt\\;How to Adjust It: You can purchase adjustable upper or lower control &lt\\;BR&gt\\;arms from a variety of sources, or you can weld washers to the &lt\\;BR&gt\\;factory control arms and re-drill the pivot holes in a new location, &lt\\;BR&gt\\;or you can cut and weld the factory control arms.&lt\\;BR&gt\\;&lt\\;BR&gt\\;How important is all of this: Well, excessive pinion angle can bind &lt\\;BR&gt\\;the u-joints up pretty good and rob quite a bit of horsepower. It’s &lt\\;BR&gt\\;not at all unusual for a car to pick up 2-3 tenths and as many mph &lt\\;BR&gt\\;after getting this straightened out. Also, excessive pinion angle is &lt\\;BR&gt\\;often the real culprit behind broken parts. Racers love to attribute &lt\\;BR&gt\\;busted driveshafts, exploded tailshafts, and cracked bellhousing to &lt\\;BR&gt\\;the raw torque and horsepower produced by their motors, when in fact &lt\\;BR&gt\\;it’s usually a problem with driveline geometry. It’s definitely &lt\\;BR&gt\\;worth checking before you break something expensive. See you in the &lt\\;BR&gt\\;lanes!!&lt\\;/TT&gt\\;&lt\\;/P&gt\\;

 

Fck this site! I’ll be on modular fords if you want more info

 

Myth #1: The pinion angle somehow affects how much traction the car
will achieve.

Straight Scoop: No way. The pinion angle doesn't mean squat as far
as the rear suspension is concerned. Think about it: why would the
suspension care about u-joint angles? What determines the "hit" on
the rear tires and the rate and amount of weight transfer is the
intersect point of the upper and lower rear bars (control arms).
That's known as the "instant center" (IC), and combined with weight
distribution, spring rates, and shock valving is what affects
traction.

Myth #2: You increased the pinion angle and the result was increased
traction, so Myth #1 must be correct.

Straight Scoop: You haven't been listening. Pinion angle doesn't
affect traction. What happened is you shortened the length of the
upper bars and that changed the intersect point, moving the IC
farther forward. You also screwed up the pinion angle in the
process. If you want to change the length of the upper or lower
bars, or change their mounting points, that's fine. But after you're
done you've got to go back and check and properly reset the pinion
angle.

Myth #3: The garage floor is the correct reference point for
measuring the pinion angle.

Straight Scoop: You've got to be kidding, right? The garage floor
doesn't have anything to do with anything. What's important is the
drivetrain angle. It so happens that professionally built racecars
are constructed so that the crankshaft is parallel to the floor,
meaning that the transmission output shaft will also be parallel to
the floor. But this usually doesn't hold true for cars using a
factory chassis. In most of those cases the engine is tipped
rearward. Take a look under the hood of your Buick and you'll see
what I mean. The drivetrain angle is the reference point and is
considered to be zero.

How to Measure It: The best way to do this is with the car supported
on jackstands, with stands under the front control arms and rear axle
tubes, with the full weight of the car resting on the stands. Next,
it's best to remove the driveshaft. Using an angle finder (these are
available from Competition Engineering or at Sears Hardware stores
they're a commonly used carpenters tool), measure across the surface
of the rear transmission seal vertically(see illustration 1). This
surface is perpendicular to the output shaft of the trans, so
subtract the measurement from 90 to get the drivetrain angle. Let's
say that the measurement is -2 degrees(pointed down). That is our
reference point. Look at illustration #3. The pinion angle is the
difference in the angle of the rearend to the angle of the
drivetrain. So, in order to have zero pinion angle, the rearend
would have to be tipped upward (pinion yoke pointing upward) 2
degrees. If our drivetrain angle measured -5 degrees, we'd have to
tip the rearend upward 5 degrees to have zero pinion angle. Get it?
Now turn the pinion yoke so that the u-joint cups are sideways, and
measure across one side of the pinion yoke vertically(see
illustration 1) where the u-joint strap connects. Again, this
surface is perpendicular to the pinion, so subtract the measurement
from 90 to get the rearend angle. compare this number to the
drivetrain angle to get the pinion angle. If the drivetrain angle
was -2 degrees(pointed down), and the rearend angle measured +1
degrees(pointed up), then the pinion angle would be -1 degree. If
the drivetrain angle had measured -2 degrees (pointed down) and the
rearend angle had measured -3 degrees (pointed down) then the pinion
angle would be -5 degrees. In my particular case, the drivetrain
angle measured -4 degrees, and the rearend angle measured -6 degrees,
resulting in a pinion angle of -10 degrees, a wasted tailshaft
bushing, and a slower than necessary racecar. The idea is to have
the pinion angle at zero with the racecar under power and going down
the track. To allow for suspension movement and loading, the pinion
angle should be at around -2 degrees for our cars.

Illustration 1





Illustration 2





Illustration 3






How to Adjust It: You can purchase adjustable upper or lower control
arms from a variety of sources, or you can weld washers to the
factory control arms and re-drill the pivot holes in a new location,
or you can cut and weld the factory control arms.

How important is all of this: Well, excessive pinion angle can bind
the u-joints up pretty good and rob quite a bit of horsepower. It's
not at all unusual for a car to pick up 2-3 tenths and as many mph
after getting this straightened out. Also, excessive pinion angle is
often the real culprit behind broken parts. Racers love to attribute
busted driveshafts, exploded tailshafts, and cracked bellhousing to
the raw torque and horsepower produced by their motors, when in fact
it's usually a problem with driveline geometry. It's definitely
worth checking before you break something expensive. See you in the
lanes!!

 

http://www.wolferacecraft.com/pinionangle.aspx

 

Nice find it has better pics then mine

 

I was told that you want your pinion a 3 degrees up b/c your transmission is 3 degrees down at ride height or is this for stock applications

 

Who ever told you that should be slapped. The whole reason you set pinion angle negative on any car and any suspension is because the axle rotates up and when it does you want it as close to straight as possible.