Pinion angle

[BAAAD68]

I don't know if any one has already asked this question yet but I wanted to know if there are any suggestions for an initial pinion angle setting on a outlaw 10.5 style car, or if there are any parameters to stick to.

[Ed-vancedEngines]

What is is your suspension type and what springs are you using?

Ed

[BAAAD68]

It's a R j racecars pro mod 4 link,I am running 14 inch springs .

[GRIFFIN]

I like a 1/2* to 1 1/2* on a 4-link set up.

[Ed-vancedEngines]

Griffin,
1/2 deg might not be enough.

What you don't want is for the pinion yoke to be over centered at full torque load, which is usually at launch. A positive pinion angle is always a No-No.

By theory you want the pinion to be lined up with driveline at maximum launch load, but if it is still slightly down that is ok and is usually the way it is set.

With a good 4 link I would suggest 1 1/2 deg down minimum and 3 deg down maximum. With fully equal length bars 3 deg is probaly a little too much, but will hurt nothing.

Do not mearure pinion angle off of what is level ground or what is normally level. You measure pinion angle against the driveline angle and the difference is your pinion angle. The pinion should never point up in a race car.

While we are on pinion angle a leaf spring car may need closer to 3 deg to even 5 deg down becuase the rear does wind up more or rotates more.

Ed

[Jake]

Base the pinion angle off the block/crankshaft, not the driveshaft. Especially in a stock engine location car. Pinion angle is nothing more than an addition to the equal phase of the front and rear ujoints for suspension design(slop). Anything more than needed is a waste of effieciency(HP to the tire).:D

I'm with Ed on his recommendations as a safe setting. You can creep down in required pinion angle if all is montitored.

[BAAAD68]

Thanks Guy's ,so I would be ok starting at 1.5 degrees then go more to figure out what the car likes the best,in what increments?
Does it effect hook or just mph?or both?
It's a brand new car and I've never had a 4 link before ,just trying to get the initial setup somewhere in the ball park.

[Ed-vancedEngines]

The more pinion angle you include it will scrub some power off but who knows if it is enough to even notice. Too great of a pinion angle can cause a vibration.

Most chassis guy I know would be setting yours up with the 1 1/2 degrees down.

Your rear end will rotate. That is a fact. Watch the wheelie bars hit or instantly go downward on cars when it is first hit at launch. The wheelie bars will dip down before the front comes up. That is from the rear end rotating in it's mountings as torque is applied. Only with a solid mounted rear axle is there no movement. Becuase of the rotation is why you need to have a flexible coupling such as a U-Joint.

Ed

[GRIFFIN]

The amount of pinion angle that a car likes and works the best with is not always the same from car to car. A car that has more flex and less braces, particulary at the point of attachment of the 4-link, will work better with a little more pinion angle. A car that is built very rigid, especially high horsepower rigid cars will use less pinion angle. I know of several cars running very fast and working very well with only 1/2* on pinion angle in them.

I do believe 1 1/2* is a good starting point for most cars. There is some cars I know of that run as much as 7*, but they are not cars that I would consider well built. They are very flexable and not consistant, I do not agree with that type of construction and theory, but that is my opinion and others may disagree with me.

To answer your question on how much of a change at one time to make. I would not change more that 1/2* at a time.

[68Bird]

Base the pinion angle off the block/crankshaft, not the driveshaft. Especially in a stock engine location car. Pinion angle is nothing more than an addition to the equal phase of the front and rear ujoints for suspension design(slop). Anything more than needed is a waste of effieciency(HP to the tire).:D

I'm with Ed on his recommendations as a safe setting. You can creep down in required pinion angle if all is montitored.


I know there are varying opinions on how to actually set the pinion angle. What I do is put my angle finder on the front of my engine and jack the rear end up until it reads 0*. Then I know the crank centerline is sitting level. Then I set the pinion angle pointing down at whatever I want less than 0*. I run -3* on my ladder bar car. Also since the car sits pretty low and the driveline is practically all inline, the angle from the pinion to the driveshaft is also very close to -3* as well.

Craig

[Ed-vancedEngines]

Let's put this subject to rest. It always evokes differences of opinions;

Ed

Here is a couple of different opionins about this;



2 Methods for
Measuring Pinion Angle



Depending on who you ask the pinion angle is the angle of the pinion relative to the Crankshaft Centerline OR the Driveshaft. I prefer the Crankshaft but I have explained both procedures below.

To measure it, you will need an angle finder that has a 360degree face and uses gravity to pull the needle. These usually come with a magnetic base and are about 3-4" in diameter.

~If all the control arms have Factory bushings: Set Pinion Angle 3 degrees to 4 degrees downward.
~If all the control arms have Poly bushings: Set Pinion Angle 2 1/2 degrees to 3 degrees downward.
~If all the control arms have Solid bushings: Set Pinion Angle 1 degrees to 1 ½ degrees downward.



Method #1- Driveshaft:


1. Place angle finder on bottom of driveshaft and write down the reading.
See diagram above.




2. Remove driveshaft.
3. Rotate the pinion so that the ujoint caps on the yoke are pointing up and down.
4. Set the angle finder on the face of the yoke where the u-bolts go through. Sometimes the face of the yoke is not perfectly flat so I lay a socket lengthwise where the ujoint caps fit then put the angle finder on the socket.




5. Read the angle and write it down.
Determine the difference between these values then decide which way the pinion needs to be rotated to achieve the proper pinion angle.



Method #2- Crankshaft/Harmonic Balancer:

1. Remove driveshaft.
2. Rotate the yoke on the rearend so that the ujoint caps on the yoke are pointing up and down.
3. Set the angle finder on the face of the yoke where the small u-bolts go through. Sometimes the face of the yoke is not perfectly flat so I lay a socket lengthwise where the ujoint caps fit then put the angle finder against the socket.
4. Read the angle and write it down.
5. Next, hold the gauge against the front of the Harmonic Balancer. This is perpendicular to the Crankshaft so makes a great place to measure the angle from. Write down this number.
Determine the difference between these values then decide which way the pinion needs to be rotated to achieve the proper pinion angle.


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AND



Pinion Angle:

Pinion angle is the difference between the driveshaft angle and the pinion angle on the differential



.

See bottom of page for pinion angle recommendations

To measure it you must be able to work under the car with the suspension fully loaded and the car level. You can place jack stands under the rear-end and under the front control arms (as close to the ball joint as possible). A drive on lift will also work for this.
There are two easy ways to measure your pinion, depending on the measuring device you have.
Protractor Measuring Device
Using an angle measuring gauge (adjustable protractor) to measure the difference between the pinion flange and the drive shaft directly. These gauges are available for under $10 from a hardware store.
Place the edge of the gauge vertically against the front of the pinion flange, beside the driveshaft.
Extend the measuring arm forward parallel to the bottom of the driveshaft.
Extend a straight edge under the driveshaft to the measuring arm of the angle gauge.
Hold the straight edge flat against the bottom of the driveshaft and adjust the measuring arm to read the angle.
Depending on the gauge you use, you may have to subtract 90° from your reading to get the correct number.
Your final measurement should be between 0 and 5.
Examine the diagram at the bottom to determine if the pinion angle is nose up or nose down.

Angle Finder Measure Device (Gravity type)
Using a gravity angle gauge (Available at hardware stores) to measure the angle between the driveshaft and the ground & the pinion flange and the ground.
Hold the gauge on the bottom of the driveshaft. Align the gauge front-to-back under the car in line with the driveshaft and read the number from the gauge (Note if angle is up{+} or down{-}). Write down this number.
Next, hold the side of the gauge against the front of the pinion flange (beside the driveshaft). Write down this number (Note if angle is up{+} or down{-}).
Subtract the first number from the second number. This is your pinion angle
Examine the diagram at the bottom to determine if the pinion angle is nose up or nose down.

Pinion Angle Recommendations:
Suspension
Recommended Angle
Using Full Wolfe Race Craft Suspension - all solid mounting points.
-1 to -1.5
Half Solid & Half Poly Mounting points
-1.5- to -2.5
All Poly mounting points
-2.5 to -3.5
All Rubber mounting points
-3 to -4.5
The more you get away from having all solid mounting points the more the rearend is going to try and rotate upward during launch. Therefore the more angle you must start with to prevent the angle from becoming positive (+). The idea is that when the rearend rotates you want the angle between the driveshaft and the pinion would be 0.

Copyright © 1999 - 2005 Wolfe Race Craft all rights reserved.





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How much driveline angle is right for my application?
Thats a loaded question. The best answer is....the least amount of driveline or u-joint angle is the best amount of angle. Try to achieve the least amount of u-joint angle but don't make it less than 1 degree. A little known fact about u-joints is that they require about 1 degree of operating angle to get the needle bearings rotating. If they do not rotate they will fail. Too much angle will also cause them to fail. The type of rear suspension also plays a big part in setting the angles as well as the engine/transmission angle. Leaf spring cars have a need for more downward pinion angle due to spring wrap-up while coil spring cars control the situation better. Hard acceleration as in the case of a drag race car requires a different setting than a street driven car. Traction bars, ladder bars, 4 links, independent rears all have special needs and requirements.

http://www.dennysdriveshaft.com/html/faq.html

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Just what is pinion angle? That is the relationship between your rear pinion gear and the drive shaft. That is your pinion shaft should be facing towards the ground (Negative Pinion angle) in relation to your drive shaft. The reason for this is that the front of your rear end wants to rotate upwards. What causes this desire to rotate up wards? As your rear tires rotate to move the car forward, the pinion gear is trying to climb up the ring gear. Imagine the pinion gear trying to spin the ring gear. The tires and weight of the car is trying to keep the ring gear from moving. Since the ring gear does not want to cooperate, what happens? The pinion gear tries to climb up the ring gear, in other words, the front of the rear end tries to go up. Take a look at the drawing. Notice that the rear is slightly pointing down as is the drive shaft. This is negative pinion angle. When the car tries to move forward, you have two things going on at the same time. First the rear end tries to move up and two it tries to form a straight line (angle of least resistance) with the drive shaft (Use the red line as a reference). Now you understand why negative pinion angle is critical. Proper negative angle allows the rear to move up just enough to satisfy the path of least resistance. On the other hand if the negative angle is too much, then the rear and the drive shaft can not form a straight line. This is not good, but not as bad as having too little pinion angle or positive pinion angle. http://restomod.us/Pinion_angle6.jpg Positive pinion angle is when the rear is facing up and not towards the ground. Imagine if you started with no negative pinion angle or positive pinion angle. As your car accelerates the rear tries to rotate up, but the path of least resistance wants to pull the rear back down (form the straight line). What will happen is the rear will get traction initially (rear rotates upward), then as the rear tries to go back down to form the straight line the tires will unload causing a loss of traction. This will alternate down the track. Not good for performance or the drive train. http://restomod.us/Pinion_angle_1.jpg In this picture I am measuring the angle of the drive shaft. I placed the protractor on the driveshaft itself. Then I read the angle of the driveshaft. Make a note of the degrees of slope and on what side of zero it is, that is right or left. http://restomod.us/Pinion_angle_2.jpg In this picture I am measuring the angle of the pinion yoke. I placed a large socket on the flat surface of the u-joint so I could take a reading. The yoke itself is not flat so you can not get an accurate reading. I noted the degree of slope and on what side of the zero it is.In this picture you cas get a better look at the protractor that I got from Sears. I am actually using 90 degrees as zero. In either case, just count the number of degrees it is on either side of the 90 (zero).
What we want to accomplish is to find out how many negative degrees there are between the rear and the driveshaft.
Take a look at your measurements. Lets say that your driveshaft had 3 deg to the left of the zero and your pinion yoke had 3 deg to the right of the zero. You would add the numbers together and your pinion angle would be 6 degrees. Here's another example, lets say that your driveshaft was 3 deg to the right of the zero and your pinion yoke was 3 deg to the right of the zero, you would now subtract them (since they are both on the same side of the zero) and your pinion angle is zero degrees.

http://restomod.us/PinionAnglePage.htm
http://restomod.us/Pinion_angle_7.jpg

[Jake]

I'm lazy,:D, I use a digital level and zero it on the crankshaft/block. I cant add and subtract very well,:D, in order to use the mechanical gravity angle finder.