Rusty Bowtie
General Category => General Discussion - Intros => Topic started by: 62131 on April 25, 2017, 07:11:51 PM
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What's your thoughts on setting pinion angle? How do you find what is needed?
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I posted this on my tech thread...Should get you pointed in the right direction.
Go to the bottom of the post and open the PDF file
http://rustybowtie.com/index.php?topic=170.0 (http://rustybowtie.com/index.php?topic=170.0)
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Put an angel finder on the driveshaft (take note of the degree its at. Unbolt the ujoint, rotate the pinion so the flat part is straight up and down, put the angle finder magnet on that and take down the measurements.
Pinion should be 2° below the driveshaft angle to compensate for axle wrap.
(Ie) ; driveshaft is 6° , so the pinion should be at 4°
At least that's how us jeepers with double cardian driveshafts do it.
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I have seen many articles written on the subject and some do recommend that the angles should take axle wrap into consideration while others do not recommend it. The thing to remember is that the real axle on a leaf spring suspension system will wrap up or down depending on whether your accelerating or decelerating but on a street driven car it will remain in the neutral position for the vast majority of the time while cruising. Because of how a u joint when working on an angle will speed up an slow down while going through each rotation they must be kept as close to the same operating angles as possible. See the quote from the info that I posted below.
"Oscillations, resulting from speed variations, can be reduced by using canceling angles .
The operating angle of the front U-joint is offset by the one at the rear of the drive shaft. When
the front U-joint accelerates, causing a vibration, the rear U-joint decelerates causing an equal
but opposite vibration. These vibrations created by the two joints oppose each other and dampen
the vibrations from one to the other. The use of canceling angles provides smooth drive shaft
operation."
Another important thing to remember is that the the joints should never be run at 0 angle as the bearings require a certain amount of movement to prevent the bearing surface from brinelling . When working with GM it was recommended to never let the angles between the two joints to differ more than .5 degrees to prevent driveshaft vibrations . Case in point was the early Cadillac rear wheel drive Brougham where customers were complaining of vibration at highway speeds where it was found that the differential angle was 1.5 degrees too low on production vehicles and the fix was to install a wedge between the spring and the mount...Problem solved. I have found that the best overall angle should be between 1 and 3 degrees with a differential of no more than .5 degrees.
Drag cars and off road cars are a whole other issue but that's for another time .
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For what it's worth I have had good luck by first setting up the engine/drive with engine intake mounting surface level. The block at the starter normally is also a level point....be sure that the car is at it's loaded ride height ie tires etc.
If the engine intake manifold is level the driveline normally angles about 2-3 degrees down, then I angle the pinion up 2-3 degrees so it's parallel with the engine tranny drive line angle.
I just tack in the rear axle until I can get the car on a 4 post lift..then the car is sitting at ride height with full weight on tires..then duplicate the engine/tranny angle with the rear pinion.
If you need any magnetic digital angle scales..I can loan you one or two.
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Ed ...The first image in the below diagram where they show no angle on the drive shaft is a perfect description of now not to set up a drive shaft. It would guarantee premature failure of the u joints. Never use 0 degrees of angle when setting up a drive shaft .
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Ed ...The first image in the below diagram where they show no angle on the drive shaft is a perfect description of now not to set up a drive shaft. It would guarantee premature failure of the u joints. Never use 0 degrees of angle when setting up a drive shaft .
10-4....don't remember ever seeing a zero angle. Heard that some Camaro's were set up similar to the 3rd diagram down...with the pinion angle down "a bit"...I assume to compensate for high performance torque "up" movement?
Would you think that no matter what the engine/trans angle is it is more important that both the drive-line and pinion angle be parallel?
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HOW ABOUT IF YOUR USING A JAGUAR REAR END OR A CORVETTE REAR END WHERE NEITHER ACTUALLY EVER MOVES AT THE PINION.
depending ON HIGH THE REAR END IS MOUNTED ON THE CROSSMEMBER, YOU COULD END UP WITH ""PERFECT IN LINE "".
Have to check my coupe when I bring it out of winter storage.
mike 8)
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For what it's worth I have had good luck by first setting up the engine/drive with engine intake mounting surface level. The block at the starter normally is also a level point....be sure that the car is at it's loaded ride height ie tires etc.
If the engine intake manifold is level the driveline normally angles about 2-3 degrees down, then I angle the pinion up 2-3 degrees so it's parallel with the engine tranny drive line angle.
I just tack in the rear axle until I can get the car on a 4 post lift..then the car is sitting at ride height with full weight on tires..then duplicate the engine/tranny angle with the rear pinion.
If you need any magnetic digital angle scales..I can loan you one or two.0
ED Thanks for the offer of the loan of the angle finders but I have some
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HOW ABOUT IF YOUR USING A JAGUAR REAR END OR A CORVETTE REAR END WHERE NEITHER ACTUALLY EVER MOVES AT THE PINION.
depending ON HIGH THE REAR END IS MOUNTED ON THE CROSSMEMBER, YOU COULD END UP WITH ""PERFECT IN LINE "".
With the factory setup on a Vette the correct offset angles are built into the engine mounts and rear diff mounts. That being said I have read a number of posts on the various Corvette sites that talk about shimming the rear pumpkin or mount and moving/adjusting the front engine mounts to achieve the correct offset.