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Old 01-26-2007, 06:07 PM
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Pinion Angle? Again?

I have searched the data base as well as I can and have not found the answer to the question of a good "rule of thumb" angle for maximum traction,least vibration. Can anybody help? My project is an 85 S-10 with mild 350 and 700r4. lowered 3".

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Old 01-26-2007, 06:10 PM
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The rule of thumb, that I remember is........The angle of the "U" joint at the tranny should be the same as the angle of the "U" joint at the pinion.
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Old 01-26-2007, 06:22 PM
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Thank you for the input. I have read where a -2 degrees will help as the axle "wraps". Any input?
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Old 01-26-2007, 06:28 PM
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Originally Posted by oldskools10
Thank you for the input. I have read where a -2 degrees will help as the axle "wraps". Any input?
We used about 0 to 2 degrees on 4-link and 6-7 on leaf springs.
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Old 01-26-2007, 07:34 PM
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I used the search function on this site...I typed in settin pinion angle and then hit go......This is what I found. The information in this post was collected from several different articles on the subject and a number of web sites. Where quotes are used the author is directly credited for his statements.

If you talk to a dozen car guys about pinion angle you?re going to get 12 different opinions. Why? Because optimum pinion angles and settings will vary depending on things such as intended use and suspension type. What works for one suspension type under one condition may not work for another. Sounds confusing doesn?t it. That?s probably why so many people ask for help on this subject. Let?s try to explain some of this mystery.

The guidelines below are specifically recommended for street driven vehicles. Settings for drag racing will differ and are especially dependent on suspension type. For instance a 4 bar rear suspension has much more control over the pinion angle under all operating conditions than a parallel leaf spring suspension does. Therefore pinion angle can be much better controlled with a 4 link and the required pinion angle can be somewhat less than a leaf spring setup. This applies to racing only. When it comes to a street driven vehicle, which is the subject of this post, the recommendations below apply no matter what suspension is used.

First we have to understand what pinion angle is. For our purpose pinion angle is defined as the angle of the pinion in relation to the angle of the drive shaft. This is measured referencing absolute level or for all intense and purposes, the ground. In the example below the angle of the drive shaft is 3* down in relation to level and the pinion is set 1* nose down in relation to level. This makes the effective pinion angle -4*.

The angle of the pinion gear isn?t the only important angle we have to deal with. There are other angles and components at play and they all have to work together to successfully transmit the engine?s power to the axles. The pinion angle?s relationship to the transmission output shaft angle (or crankshaft angle) and driveshaft angle is also extremely important. This relationship defines the angles at which the ?U? joints operate and according to Ray Currie of Currie enterprises, ?universal joints are designed to handle angles between 1 and 3 degrees. If a U-joint is forced beyond this normal range, it can hyperextend and lead to catastrophic failure.? In the example above the ?U? joint would be operating at 4 * or outside its designed parameters. This is why we need to control the relationship between pinion angle, the angle of the drive shaft and the angle of the transmission. Each affects the other.

According to Currie, ?a street driven vehicle should strive for between 1 and 3 degrees between the transmission and driveshaft, and 1 to 3 degrees between the driveshaft and pinion. Furthermore, the two angles should be nearly equal (between 1 and 3 degrees), but always opposite.? Otherwise stated, ideally, the angles between the transmission output shaft and driveshaft, and between the driveshaft and the pinion will be equal and opposite and 3 degrees or less. See the example below.

When setting pinion angle it is important to remember that exceeding the above parameters will result in premature wear of ?U? joints and angle induced vibrations in the drive train. Greg Frick of Inland Empire Driveline explains it this way. ?As the front U-joint gets the power delivered to the driveshaft, it transforms smooth engine power into pulsating power. This happens because the U-joint travels an elliptical path caused by the angle through which it operates. You can visualize this by looking at a dinner plate straight on.

If you tilt it the round plate appears to become an ellipse. In traveling this ellipse, the U-joint speeds up and slows down twice per shaft revolution. A second U-joint having an equal but opposite angle is used to convert this pulsating power back into smooth power feeding the pinion. The bigger the working angles are, the more violent these speed changes become.? Deliberately setting the pinion at a lesser angle is common on drag cars where the drive line is generally under full power however using this type setup on the street will result in annoying vibrations every time you back off the throttle. This is why it is extremely important to limit the angles to 3* or less.

In summary, it isn?t just the pinion angle that?s important. It?s the relationship between the driveshaft, transmission output shaft, and the pinion gear that is important and this relationship governs the angles at which the ?U? joints operate. It?s really not that difficult. All you have to do is keep the pinion angle and the transmission output shaft angles as close to parallel as possible and try to keep both angles at 3* or less. This is relatively easy for a full sized vehicle but the shorter the drive shaft the harder it is to control these angles.

There is also a school of thought that having some pinion angle is not required. Yes a driveline will work with 0 pinion angle however the "U" joints need a slight angle for proper lubrication. Running with 0 angle will prematurely wear out "U" joints.
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Old 01-26-2007, 08:39 PM
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an excellent source for complete and illustrated information on driveline angles is "tom woods driveshafts". Do a google search on his shop and get a paper and pencil handy.That was probably the most detailed reading I've ever come across. I'm building a cj5 with 39.5 boggers ,7 inches of lift , and a very short rear driveshaft. My shaft angles are FAR beyond 3* and require a different type of joint, but the information that helped me will be invaluable for anyone who wants a good description on this subject. Hope this helps.
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Old 01-27-2007, 08:05 AM
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Pinion Angle? again?

Hmm , Good Readin . My understandin was 4 -6 Deg. But on the one I just set up I went 4 Deg. Reason was Jackin Differential up I spun the tire's . Watched the Drive line .
Way I watched the drive line was with 2 Pointers . << welded the Pointers too Adjustable , Jack stand's . Put um 1/8 inch away . Spun the Tire's .
4 Deg. Just looked better, Was straighter . But Just looked right .
As in I played with it for hour's .
Cant' really explain what I mean , By it just looked right . But It just looked like what I imagined a Drive shaft would spinn like . << Has a look too it !

Way I set mine was with Motor Looose Hangin on Cherry Picker, and Tranny Loose . Then I used A metal bar too tack weld the engine too the frame , Various posistions . Same with Tranny .
I used A chalk line On Flatt concrete For center Line . Then a Frameing Sqaure on Center Mark of the Crank Pulley, off of chalk line .
I used a Lil plastic degree pointer compass from the rear of the differential houseing . And a Level on both motor , and the Differential, cross way's .
I tried 3 Deg. Too 6 Deg. Various Height's and Level's of engine and tranny .
4 Deg. Looked right . I probably studied on it 2 -3 Day's, playin with Various posistion's . Came up with 4 degree's .

But Im no expert ? Done few set up's before , Jethro style ?
Seemed too work out . As in No vibration's .
One I just did ? I wont ever get a see it Runn Probably ? Guy I did it for ? I had too runn off . Was an idiot . AKA Druggy/ drunk !

But, I like Henry's Precise Explanation . Just wonderin here If we could gett a Step by Step Instruction . On how too set one up ?
But think If you Jack differential up . Spinn the Tires Watch Drive line ?
You will see what I mean . By just look's right ! What you would imagine , in your head a drive line would spinn like ?

But Im interested in how , the expert's do it . Refine my Technique , a lil better . Take a more proffessional aproach , to it . A step by step , on how too set a Motor and trans and Diff , At the right Pinion angle . Mostly I started out Studying on my Ford Truck's ? << Kinda Copied it and , Made kidds push it up and down the drive way, couple 100 times, while I watched, Drive line ? Way Ive Done it . Seem's too work out ? But then again, me and Jethro is 1st Cousin's ?

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Old 01-27-2007, 01:48 PM
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O.K. guys, using what I have on hand today I came up with 5 degrees using a protractor and the vibration is gone. The driveline also "looks better" as Jethro said. Gonna give it a try for a while. Thanks to all for the great information!
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