Pinion Angle ??
04-24-2007, 06:10 PM
#44
Originally Posted by MADMAN
I'm out a here. I will go back to my building of cars that actually hook and leave this discussion to you guys 
04-24-2007, 06:10 PM
#45
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the suspension doesnt care if the pinion is parallel to the ground. the reason for putting -2 degrees on the pinion is so that when under load it will be as close to zero as possible. in other words, while your going down the track under load, your driveshaft wouldnt even need u joints... it could be a solid shaft in a perfect world.
setting it off the ground could net you -5 or whatever, and you might still have -3 degrees while your going down the track. not the way to do it if you ask me.
pinion needs to be measured in relation to the driveshaft, and also you need to make sure the trans yoke is good in relation to the driveshaft.
my car is setup to zero angle on the front u joint, and -1 degree pinion angle. 1.32 60' so far with a car making around 420-440rwhp on the bottle. 28" tire.
setting it off the ground could net you -5 or whatever, and you might still have -3 degrees while your going down the track. not the way to do it if you ask me.
pinion needs to be measured in relation to the driveshaft, and also you need to make sure the trans yoke is good in relation to the driveshaft.
my car is setup to zero angle on the front u joint, and -1 degree pinion angle. 1.32 60' so far with a car making around 420-440rwhp on the bottle. 28" tire.
04-26-2007, 12:54 AM
#50
gollum... thats a great link for the most part. thanks for posting it. some of it is a little off like:
Straight Scoop: You've got to......... It so happens that professionally built racecars
are constructed so that the crankshaft is parallel to the floor,
meaning that .................
Thats not realy the case. Let's say for example im building a car with around a 9.5" crank height, and im running a 34.5 tire on the rear. I build my cars to have a straight shot from the front of the crank through the trans straight into the pinion on the rear. This car would have the engine/trans centerline going uphill from front to back(trans output shaft higher then front of crank). The driveline parallel to the ground in this application wouldn't accomplish anything. Once the car is built, I then stick about -1.0 to -1.5 degrees pinion angle on a heim joint car.Once the rear tries to wrap up, everying idealy would be completely straight and the u joints wouldn't have to overcome any angles and sucking up any horsepower. but anyway.. thats just how I do it......
Straight Scoop: You've got to......... It so happens that professionally built racecars
are constructed so that the crankshaft is parallel to the floor,
meaning that .................
Thats not realy the case. Let's say for example im building a car with around a 9.5" crank height, and im running a 34.5 tire on the rear. I build my cars to have a straight shot from the front of the crank through the trans straight into the pinion on the rear. This car would have the engine/trans centerline going uphill from front to back(trans output shaft higher then front of crank). The driveline parallel to the ground in this application wouldn't accomplish anything. Once the car is built, I then stick about -1.0 to -1.5 degrees pinion angle on a heim joint car.Once the rear tries to wrap up, everying idealy would be completely straight and the u joints wouldn't have to overcome any angles and sucking up any horsepower. but anyway.. thats just how I do it......
Last edited by promod1955; 04-26-2007 at 01:08 AM.
04-26-2007, 05:13 AM
#51
Originally Posted by promod1955
I build my cars to have a straight shot from the front of the crank through the trans straight into the pinion on the rear. Once the car is built, I then stick about -1.0 to -1.5 degrees pinion angle on a heim joint car.Once the rear tries to wrap up, everying idealy would be completely straight and the u joints wouldn't have to overcome any angles and sucking up any horsepower. but anyway.. thats just how I do it......
04-26-2007, 08:09 AM
#52
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Originally Posted by gollum
This makes verygood sense when bulding a racecar from bottom up. Is pointing the trans strait at rear pinion easy to do with our stock late model Fbodies?
04-26-2007, 09:53 AM
#53
gollum. Its possible but you need to determine the size rear tire your going to run and then the ride height you want before you do anything. When you get them real low, a lot of times the torque arm hits the transmission tunnel so you have to modify that
04-26-2007, 10:12 AM
#54
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http://buickperformance.com/Pinion.htm
****edit, oops, saw this link was already posted....lol O well
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.
if your overall driveline angle is not close to zero you can possibly introduce high speed vibrations from the difference in angular velocities of the u-joints. u joints are not CV joints and are not made to be run at different angles relative to each other. I had a high speed vibration that I got rid of by simply adjusting my pinion angle to match my tranny output shaft angle so both of my ujoint angles are the same (0° driveline angle). When I think of a -2° pinion angle that means that my pinion is tipped "downward" 2° from a 0° driveline angle.
****edit, oops, saw this link was already posted....lol O well
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.
if your overall driveline angle is not close to zero you can possibly introduce high speed vibrations from the difference in angular velocities of the u-joints. u joints are not CV joints and are not made to be run at different angles relative to each other. I had a high speed vibration that I got rid of by simply adjusting my pinion angle to match my tranny output shaft angle so both of my ujoint angles are the same (0° driveline angle). When I think of a -2° pinion angle that means that my pinion is tipped "downward" 2° from a 0° driveline angle.
04-26-2007, 10:22 AM
#55
LS1Tech Co-Founder
iTrader: (34)
I think the 4th gen is designed so that the driveline is even with the frame, I recall talking to Mike @ Yank about automatic transmissions and I thoght he said that the 4L60E is designed to be parallel to the frame/ground.
