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Unread 05-15-2011, 12:18 PM   #1
ChicoXJ
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How to set driveline pinion angles

Since I am not a member, and since you do not have an official post on how to set driveline pinion angles, I thought I would post here. Driveline pinion angles come up often and I get tired of going through the same thing repeatedly, so I thought a post was in order so we would all have access to this information. It is also easier for me to just give a link to our own website. So here it is.

It is not all that hard. You just need to do what professionals do. I have done this many times. First, you need to purchase an angle finder, or if you have an Android, download an angle finder app. The angle finders are cheap and look like this:



The pic above shows you how to measure off the pinion. Then place the angle finder on the the fill plug or any other vertical machined surface on your transfer case and measure that. Next, what you do depends on whether or not you have a SYE or standard set up.

If you have a standard setup with a stock tcase, your driveline geometry needs to like like this:



If this is the case, you will subtract one value from the other and that is the number of degrees you need to change the pinion. It needs to match as close as possible the angle on the tcase. This can be done with shims, or if you have not welded your spring purchases you can rotate the axel housing till you get the right angle and then tack weld them in place.

If you have an SYE (slip yoke eliminator) and a double cardan U joint on the tcase end of the driveline, then the geometry you need is this:



To get this, loosen the ubolts and place a jack under the pinion and raise the pinion until the driveline angle is the same as the pinion angle, or an easy way to put it is just raise it until the pinion U joint has no angle to it. It needs to look like this.



Measure the new pinion angle and then subtract the first value from the second and then that is the amount of shim you need, or if you have not welded the spring pads then tack weld them in that position.

As long as you have not exceeded the angle the U joints will accommodate without the yokes hitting, you will have vibration free driving.

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Unread 05-15-2011, 12:34 PM   #2
LT1CJ7
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Nice, But you forgot to mention for the not so mechanically inclined folks,
That you must have the vehicle on a flat level surface before taking any measurements.
Also, proper air pressure in all tires with all tires being the same size.
Another note, Is to be sure to have your T-case in the location where you plan on keeping it "drop/No drop"
And another note, Changing front pinion angle will screw up caster if the inner C's have not been cut & turned.
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Unread 05-15-2011, 01:47 PM   #3
RidgeRat
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Why does it cause more vibration to reduce the angle at the diff for a standard drive shaft? Seem like the less angle you have at either/both ends would be better. What's the physics here that I'm not seeing?
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Unread 05-15-2011, 03:33 PM   #4
ChicoXJ
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The driveshaft universal joint dose not travel in a circular motion like you would think. It travels in an ellipse, or more like an egg shape. The angle of the universal joint determines the amount of ellipse there is. So that is why you must align the yokes on the ends of a standard drive line and match angles. Otherwise, you will either have the ellipses out of sinc or if the angles are different you will have different shaped ellipses. Either situation will cause a vibration.
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Unread 05-15-2011, 04:40 PM   #5
gojeepin
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Quote:
Originally Posted by ChicoXJ View Post
Since I am not a member, and since you do not have an official post on how to set driveline pinion angles, I thought I would post here. Driveline pinion angles come up often and I get tired of going through the same thing repeatedly, so I thought a post was in order so we would all have access to this information. ...
Well, we have a sticky that covers that and more... but we always welcome assistance. It's also in my signature.


Quote:
Originally Posted by ChicoXJ View Post
The driveshaft universal joint dose not travel in a circular motion like you would think. It travels in an ellipse, or more like an egg shape. The angle of the universal joint determines the amount of ellipse there is. So that is why you must align the yokes on the ends of a standard drive line and match angles. Otherwise, you will either have the ellipses out of sinc or if the angles are different you will have different shaped ellipses. Either situation will cause a vibration.
Well, u-joints are a 4-pole system and the u-joint does travel in a circular path on two poles. The other two poles will travel in an ellipse unless the drive shaft is pointed straight at the pinion (no deflection angle).

The following is for a standard drive shaft.

1) Starting with the transfer case, the circular path is from the driving side and is CV.
2) The elliptical path is on driven side (drive shaft) and makes two speed changes per revolution. The greater the deflection angle, the greater the speed changes.
3) To insure your output from the drive shaft is CV again, the operating deflection angle from the drive shaft to the pinion have to match the other end.
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Vibration? Bump steer? Wandering? Read: Steering, suspension, and driveline basics. An article on how it works and where to look for problems.

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Unread 05-15-2011, 04:46 PM   #6
ChicoXJ
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Quote:
Originally Posted by gojeepin View Post
Well, we have a sticky that covers that and more... but we always welcome assistance. It's also in my signature.




Well, u-joints are a 4-pole system and the u-joint does travel in a circular path on two poles. The other two poles will travel in an ellipse unless the drive shaft is pointed straight at the pinion (no deflection angle).

The following is for a standard drive shaft.

1) Starting with the transfer case, the circular path is from the driving side and is CV.
2) The elliptical path is on driven side (drive shaft) and makes two speed changes per revolution. The greater the deflection angle, the greater the speed changes.
3) To insure your output from the drive shaft is CV again, the operating deflection angle from the drive shaft to the pinion have to match the other end.
My response was for a standard driveline, not CV. It is its own complete driveline. Terminology was from Tom Woods website.
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Unread 05-15-2011, 04:52 PM   #7
LT1CJ7
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Quote:
Originally Posted by ChicoXJ View Post
Terminology was from Tom Woods website.
Woods don't know the difference between their A$$ & a U-joint
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Unread 05-15-2011, 05:18 PM   #8
gojeepin
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Quote:
Originally Posted by ChicoXJ View Post
My response was for a standard driveline, not CV. It is its own complete driveline. Terminology was from Tom Woods website.
Yep... mine too. I never mentioned a CV drive shaft.
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Vibration? Bump steer? Wandering? Read: Steering, suspension, and driveline basics. An article on how it works and where to look for problems.

83 CJ7, 4.1L 6cyl (4.0L bored .030" over), 35" tires, T-5 transmission, Dana 300 TC, Trussed AMC 20.
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Unread 05-15-2011, 05:48 PM   #9
ChicoXJ
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Quote:
Originally Posted by LT1CJ7 View Post


Woods don't know the difference between their A$$ & a U-joint
I don't want to start some sort of huge argument here, but if you feel that way fine. But I do think they know something, being in the business and all. I have three of their drivelines and find them satisfactory.
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Unread 05-15-2011, 05:51 PM   #10
ChicoXJ
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Quote:
Originally Posted by gojeepin View Post
Yep... mine too. I never mentioned a CV drive shaft.
OK, maybe we are picking nits here, maybe not. I am not going to belabor the point. My apologies for any perceived mistakes. However the driveline setup procedure is correct. As I have said, I have set up many. My attempt was to pass on enough information so that anyone here could set up a driveline without guessing and just buying shims on a whim to throw at it.
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Unread 05-15-2011, 05:52 PM   #11
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Quote:
Originally Posted by LT1CJ7 View Post
Nice, But you forgot to mention for the not so mechanically inclined folks,
That you must have the vehicle on a flat level surface before taking any measurements.
Not to contradict anyone but actually, for determining U joint angles, that really isn't necessary because you are looking at relative angles. The angle of the pinion relative to the angle of the transfer case output shaft, the angle of the pinion and the angle of the transfercase output shaft relative to the angle of the drive shaft.
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Unread 05-15-2011, 07:47 PM   #12
gojeepin
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Quote:
Originally Posted by ChicoXJ View Post
OK, maybe we are picking nits here, maybe not. I am not going to belabor the point. My apologies for any perceived mistakes. However the driveline setup procedure is correct. As I have said, I have set up many. My attempt was to pass on enough information so that anyone here could set up a driveline without guessing and just buying shims on a whim to throw at it.
Your procedure is mostly correct. You know, even though I like Tom Woods and have bought driveshafts from him before, his diagrams are so simple as to be inaccurate...

If you followed the Tom Woods diagrams exactly, you could still have some vibration since the pinion pitches up and down somewhat during operation. Depending on your springs, bushings, etc., your pinion could pitch upward 2* or so during acceleration.

The Tom Woods double cardan (CV) shaft illustration presents the double cardan module in the incorrect orientation but you'd have to look at my illustration to see why.

I did that article because the same I was addressing the same issues again and again.

Thanks for your input and for helping out fellow Jeepers to set up their drivelines.
__________________
Vibration? Bump steer? Wandering? Read: Steering, suspension, and driveline basics. An article on how it works and where to look for problems.

83 CJ7, 4.1L 6cyl (4.0L bored .030" over), 35" tires, T-5 transmission, Dana 300 TC, Trussed AMC 20.
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Unread 05-17-2011, 03:11 AM   #13
langstonjones
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Quote:
Originally Posted by gojeepin View Post
Your procedure is mostly correct. You know, even though I like Tom Woods and have bought driveshafts from him before, his diagrams are so simple as to be inaccurate...

If you followed the Tom Woods diagrams exactly, you could still have some vibration since the pinion pitches up and down somewhat during operation. Depending on your springs, bushings, etc., your pinion could pitch upward 2* or so during acceleration.

The Tom Woods double cardan (CV) shaft illustration presents the double cardan module in the incorrect orientation but you'd have to look at my illustration to see why.

I did that article because the same I was addressing the same issues again and again.

Thanks for your input and for helping out fellow Jeepers to set up their drivelines.
Mike, that document on steering and suspension is out of this world FANTASTIC!! Now I can give google a break when I'm reading these threads because I had no clue as to what most of the terms were that people were using. Thanks and I will be keeping a copy of that one for sure.
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