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Thread: setting your pinion angle

  1. #1
    Registered User Yenko's Avatar
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    setting your pinion angle

    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.

    Craftsman Magnetic Universal Protractor
    http://www.sears.com/sr/javasr/produ...id=00939840000

    1. Place angle finder on bottom of driveshaft and write down the reading.See attached diagram below.
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  2. #2
    Registered User Yenko's Avatar
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    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.

    *Note*
    Sometimes the face of the yoke is not perfectly flat so lay a socket lengthwise where the ujoint caps fit then put the angle finder on the socket
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  3. #3
    Registered User Yenko's Avatar
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    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.
    ISRA# 18696

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  4. #4
    Registered User Yenko's Avatar
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    Reference table that I used to set the pinion and drive shaft angle in the attached picture below.

    With -18 degree's, you'll need a 15 degree shim to achieve a -3 degree pinion and drive shaft angle.

    The middle table (-2 +(-2)=-4) is what you need to achieve to get the right pinion and drive shaft angle. The pinion yoke is -2 degree's and the drive shaft is -2 degree's, that will give you a total of -4 degree's pinion and drive shaft angle. Anywhere from -5 to -3 is what you want. Some people say that you only need -3 to -1 to achive this but what about when the drive train torque up? You will loose anywhere from 1 to 2 degree's. So, I would stick from -5 to -3 degree's.

    The reference table shows you how to add or subtract avia your reading from the pinion yoke and the drive shaft angle.
    ISRA# 18696

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  5. #5
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    Cliff,

    Thanks for this post! I'm going to set it up at the top of the forum as a sticky.. :bigthumb:
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  6. #6
    Registered User Yenko's Avatar
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    Thanks Sean,

    Yenko
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  7. #7
    Registered User Yenko's Avatar
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    Quote from Craig Watson's website

    Here is Craig Watson's guide to checking the relative angle between the centerline of the pinion gear in the rearend and the centerline of the driveshaft. This is known as pinion angle. Pinion angle is important due to the forces at work in the rearend and rear suspension of a rearwheel drive vehicle. As power is applied to the rearend via the driveshaft, the pinion gear tries to climb the ring gear. This causes the rearend housing (along with the pinion gear) to rotate about the axles' centerline. The optimum relationship between the pinion gear and driveshaft is when they are perfectly aligned. In order to achieve this under power, you must have some angle built into the setup when the vehicle is at rest and not under any power.

    The typical leaf spring rear suspension will need 5-7 degrees of negative angle. A ladder bar or 4-link setup is much more rigid and therefore usually only needs 1-3 degrees. You never want the the rearend setup with positive pinion angle. This is when the yoke of the rearend is tilted upward more than the driveshaft. This can lead to binding of the u-joints and will hurt traction (the real reason we enthusiasts are concerned about this).

    To check the pinion angle, the vehicle needs to be sitting with its weight on the tires, as it would be normally. For the best accuracy, place weight in the driver's seat to simulate the driver. An angle finder can be bought from places such as Sears for about $10. Begin by measuring the angle of the driveshaft and writing it down. Then remove the driveshaft from the yoke (no need to totally remove it and spin tranny fluid everywhere) and place the angle finder on the end of the yoke. The angle from vertical will be equal to the angle of the centerline of the pinion gear to the horizontal. If the driveshaft was angled upward (it would be rare to find one that isn't) and the rearend is nose down (not always the case, so be sure you know which way its positioned), just add together the two angles you measured. For instance, if the driveshaft is 2 degrees up from level and the pinion gear is 3 degrees nose down, then you have 5 degrees of pinion angle. If the rearend is nose up and its angle is less than the angle of the driveshaft, subtract the rearend angle from the driveshaft angle. If the angle of the rearend is steeper than that of the driveshaft, subtract the angle of the driveshaft from that of the rearend to see how much positive pinion angle you have. For example, if you have a rearend angle of 5 degrees from vertical nose up and the driveshaft is angled up at 3 degrees, you have 2 degrees of positive pinion angle. If this was a leaf spring car, you'd need to change the angle by 7 degrees to get 5 degrees of negative pinion angle.

    If the rearend is so close to level that you can't tell if its nose up or nose down, put the angle finder on the yoke and then see which direction you have to rotate the finder to make it read zero (or 90 depending on how the angle finder is made). When viewed from the passenger side, if you have to rotate it counterclockwise, the rearend is nose down.

    Now that you know the pinion angle, you may have to change it. On a leaf spring car, this is done with wedges between the rearend and the springs. Speed shops and sometimes alignment shops keep these around. If you can't find them locally, Summit and Jegs carry them. If you have a factory 4-link car, you'll need some adjustable control arms or revised control arm mounts. Aftermarket ladder bar and 4-link cars are adjusted via the Heim joints.
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  8. #8
    Registered User ZZ4Blazer's Avatar
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    Cliff,

    If Im understanding your example correctly, you'd need to shim the rear end 15 degrees to align it up. And, the rear end would have to come up those 15?


    In that case, that would be more like a very lifted vehicle? Like a truck with a large suspension lift?
    Jim 94 Stepside
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  9. #9
    Registered User Yenko's Avatar
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    Originally posted by ZZ4Blazer
    Cliff,

    If Im understanding your example correctly, you'd need to shim the rear end 15 degrees to align it up. And, the rear end would have to come up those 15?


    In that case, that would be more like a very lifted vehicle? Like a truck with a large suspension lift?
    Yes, 15 degree's is correct. But keep in mind, the transmission plays a role in this as well. The transmission has to be at 1-3 degree as well as the rear end angle. I don't know if you have noticed, but the carburetor mounting surface on the intake is not straight. It has a few degree's built in it also. If you use a low profile transmission mount, that will change the angle of the yoke in the rear transmission housing. Altering the height of the cross member will change the angle also. Raising/lowering the motor will change the angle. I have another theory about angle changes but I need to talk to a chassis builder before I bring that subject up. I don't have any numbers in front of me, but lowering the suspension three inch's is several degree's. A u-joint has to have 1-3 degree's against the caps for the roller bearings to be able to rotate inside the u-joint cap.

    Maybe that was a bad example, but I was trying to show the extreme view behind the whole idea of setting pinion and drive shaft angles.

    *Note*
    The attached picture is what the driveline should look like when the angles are right.
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  10. #10
    Registered User ZZ4Blazer's Avatar
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    I was waiting for the transmission role to come into play, lol.


    Iv'e never actually measured, but I assumed that the intake manifold was angled to let the carb lay flat. If I remember right, most motors should have 3-4 degrees angle on them, towards the back of the vehicle. Angling the tranny down 3-4 degree's. I think thats what factory is.

    Cliff, let me ask you this. I thought you had 3" drop leafs in the back of your truck. And, recently fixed a driveline angle problem.

    If you would put the angle finder on your pinion yoke, is the yoke angled up, or down?
    Last edited by ZZ4Blazer; 01-21-2004 at 06:34 AM.
    Jim 94 Stepside
    ZZ430 clone V8
    NX kit in the works
    Tremec T56 6 speed
    8.5" rear
    Quote Originally Posted by Harley
    Go before show any day of the week.

  11. #11
    Registered User Yenko's Avatar
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    Originally posted by ZZ4Blazer
    Cliff, let me ask you this. I thought you had 3" drop leafs in the back of your truck. And, recently fixed a driveline angle problem.

    If you would put the angle finder on your pinion yoke, is the yoke angled up, or down?
    Jim, I did have 3" drop leaf springs. But I bent the driver side leaf spring with my first motor. The traction bar was not long enough to reach the eyelet and the torque of the motor bent the spring since the traction bar was against the leaf spring. So, I had to take them off cause that bent leaf spring made my truck lean on the driver side.

    And yes, I did fix my drive line angle problem. I started this thread cause I have recently had a few PM's asking about pinion angles. So, I thought I would start a thread to help others out.

    To answer your question, the pinion yoke will be pointing down, same thing goes for the end of the drive shaft.

    The transmission angle has to be set right before the pinion angle can be set. Always remember, you want a negative angle, not a positive angle. But...you can have a positive angle as long as the total angle is negative. What I mean by that is the pinion angle and the drive shaft angle total up too. Let me give you a few examples.

    In the example below, the first angle will be the pinion angle and the second angle will be the drive shaft angle.

    #1 example
    -4(pinion yoke points down) + 1(drive shaft points up)= -3 degree's total pinion and drive shaft angle.
    -4 + 1 = -3 degrees total

    #2 example
    3(pinion yoke points up) + 2(drive shaft points up)= +5
    3 + 2 = +5 degrees total

    The next example is kind of my problem that I'm dealing with. The problem starts with my transmission mount that I'm using. My transmission mount is for a 91 Firebird Formula with a 5-speed manual transmission. That mount that I'm using, is almost 1 inch taller than any other mount that I have checked on. To correct my transmission angle problem. I've raised my motor up by putting washer's in between my block and the stealth V8 conversion mounts that I'm using. The problem was fixed, but my 2.5" exhaust is now closer to the floor pan. So, I used a motor tie down to keep the exhaust pipe from hitting the floor pan when I get into the motor. The 2.8 frame mounts are not strong enough to keep the motor from flexing under a hard strain. So, my job for this week end, is to lower the motor back down and to take the motor tie down off the motor(I'm tired of the motor shacking the truck since the motor is tied down). In doing this, my transmission angle will be messed up again. What I'm going to do is, fabricate up a mount on the transmission cross member so that I can lower or raise my transmission. That way, I can still keep my transmission mount, but I will be able to set my transmission angle right. If your wondering, yes my pinion angle will be off when I do this. I don't know, I might just totally make a new cross member. Ok, since I bored you with that story, back to the last example...lol.

    #3 example
    5(pinion yoke is pointing up) + 7(drive shaft is pointing up)= +12 total degree's
    5 + 7 = +12 degrees total(pinion yoke and drive shaft is pointing up)
    +12 degree's will wear out the rear end u-joint real fast(that will cause a bad vibration).

    These are not my numbers, but there some where in the ball park. That last example, you would need a 15 degree shim or 15 degree's built into the drop blocks to fix this kind of problem.

    Got any more question, just ask.
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  12. #12
    Registered User ZZ4Blazer's Avatar
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    If I can ever get the welder off my uncle, Im gonna weld up a new, double hump style tranny crossmember. Basically redoing the whole thing.

    Same with the rear end. As soon as I get that rebuild, Im starting from scratch with that too. Should be ordering my steel blocks soon. Going to get an assortment of shims from summit while Im up there as well.

    Just gonna load the suspension, and see what kinda angles I have, then go from there.

    I know my trucks gonna have the abilities to see 140+, should have the brakes and handling to do is soon as well. I want it smooth all the way there.

    Thanks for the info Cliff. Im sure I'll have a few more questions for you as Im doing it.
    Jim 94 Stepside
    ZZ430 clone V8
    NX kit in the works
    Tremec T56 6 speed
    8.5" rear
    Quote Originally Posted by Harley
    Go before show any day of the week.

  13. #13
    Senior Member bigjsp's Avatar
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    Originally posted by ZZ4Blazer
    I was waiting for the transmission role to come into play, lol.


    Iv'e never actually measured, but I assumed that the intake manifold was angled to let the carb lay flat. If I remember right, most motors should have 3-4 degrees angle on them, towards the back of the vehicle. Angling the tranny down 3-4 degree's. I think thats what factory is.
    I prefer to use the crankshaft method which factors the crankshaft angle into the calculation. Ideally under power the centerline of the crank will be parallel to the centerline of the pinion. The relative stability of suspensions is indicated by the fact that a 4 link needs - 3 degrees and a traction bar needs -7.

    THere are even arguements as to what the amount of pinion angle should be relative to horsepower and also to the type of bushings in a 4 link. On our drag car we are suppose to run - slightly more pinion angle when we have the big motor in versus our bracket motor.

  14. #14
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    do you know if all drops will require adjusting the pinion angle? What I guess I mean is, a 2/3 probably wont, but a 5/5 will absolutely require adjustment.
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  15. #15
    Registered User loco4christ's Avatar
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    Cool Question??

    If I go to a place to have my blazer lowered, there going to set the cant, I think its called allready so I wont have to worry right??

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