Driveshaft Angle and Phasing

[HotRodPC]

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For those who don't think angles matter, especially on front and rear driveshaft angles when configuring lift kits. Geometry and Phasing is VERY IMPORTANT.

 

[77 K20]

That was a very cool demonstration on that. Thanks for posting it.

 

[MikeB]

Nice video.

However, I don't quite understand phasing. But it's not a factor on my short bed truck's one-piece drive shaft with yokes welded on both ends.

 

[firebane]

Nice video.

However, I don't quite understand phasing. But it's not a factor on my short bed truck's one-piece drive shaft with yokes welded on both ends.

Phasing is keeping them all in sync to prevent premature wear and things like vibration.

 

[MadOgre]

Oh ya so phasing is having the U joints lined up so the front and rear u joints are not at different rotation spots on the shaft. Notice how he turned the left u joint counter clock wise from the right u joint? This is phasing. The 2 need to be in the same clocked position on the drive shaft.

 

[MikeB]

What I should have said is I don't understand how you'd properly phase a 3-piece drive shaft, because the center u-joint creates a 180 degree shift. My guess is the ends are 180 degrees out of phase, which places both ends in phase with the center.

 

[MadOgre]

OH haha Im wondering how the angles work with the double Cardan joint too. specifically the angle at the pinion for the last u joint?

 

[73 C10]

OH haha Im wondering how the angles work with the double Cardan joint too. specifically the angle at the pinion for the last u joint?

I'm wondering the similar thing but with a two piece drive shaft in my axle flipped c10. I need to look closer, but I don't know if I can just clock my axle or if I need to cut some out of the middle driveline bearing carrier mount. Obviously I just want to clock the axle. The pinion is about 6* nose up from neutral to the back driveline. I thought it should be about 2* down. So I thought I could just clock it 8*. But to keep the input and output parallel and the angles equal and opposite, I need to take some measurements and rethink things.

 

[Georgeb]

Seems to me I have seen driveshafts with un-equal angles at each end from the factory. Not much but some. I wonder if there is a certain level of allowable difference. Obviously it's important but the differences in the video were pretty pronounced for demonstration purposes. I imagine the further off you get the more pronounced the change in speed and it probably isn't a linear change.

 

[73 C10]

Good thought.

Any thoughts on this? Let's say my trans pan is 0* (not relative to the ground). The first drive line section is 5* down, the second section after the u joint is back to 0*, and the pinion angle is 5* down (nose up). To clarify this would be looking at it from the drivers side going front to back.

That makes the trans parallel with e second section, angles equal and opposite, and the first section parallel with the pinion, angles equal and opposite.

This seams perfect right?

Except for the nose up part bugs me. Maybe nose up is OK as long as I set the pinion the standard 1-2 deg* extra nose down to allow for a little power to raise the nose back to 5*. That would mean, set the nose up 3*.

I hope someone can follow that.

Is nose up OK with axle wrap in mind?

 

[Keith Seymore]

Good thought.

Any thoughts on this? Let's say my trans pan is 0* (not relative to the ground). The first drive line section is 5* down, the second section after the u joint is back to 0*, and the pinion angle is 5* down (nose up). To clarify this would be looking at it from the drivers side going front to back.

That makes the trans parallel with e second section, angles equal and opposite, and the first section parallel with the pinion, angles equal and opposite.

This seams perfect right?

Except for the nose up part bugs me. Maybe nose up is OK as long as I set the pinion the standard 1-2 deg* extra nose down to allow for a little power to raise the nose back to 5*. That would mean, set the nose up 3*.

I hope someone can follow that.

Is nose up OK with axle wrap in mind?

"Nose Up" (relative to the ground) is immaterial; the driveline is only interested in the working angles between the various components - regardless of the relationship to the ground.

The truck could be upside down - but that wouldn't change the relationship between the driveline components.

See if this helps:

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Summary: equal, opposite and "small" (less than three degress or so) is the key. Don't pay any attention to where the ground is. You can use angle shims to achieve the desired rear u joint working angle (cutting the center section out would be a bit extreme; perhaps only for the most hard core perfectionist).

K

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[Keith Seymore]

That was a very cool demonstration on that. Thanks for posting it.

x2. Excellent video (I have seen that before).

Oh ya so phasing is having the U joints lined up so the front and rear u joints are not at different rotation spots on the shaft. Notice how he turned the left u joint counter clock wise from the right u joint? This is phasing. The 2 need to be in the same clocked position on the drive shaft.

This is correct.

However, the manufacturer has taken care of that for you. As a hobbyist you shouldn't have to worry about phasing unless you are building your own new shaft from scratch.

Also - different philosophies about phasing come and go. For a while it was en vogue to have a couple degrees difference in phase to allow for radial compliance in the shaft (sort of Kentucky windage). That has now gone by the wayside and we now phase the shafts straight up, as we had done previously.

OH haha Im wondering how the angles work with the double Cardan joint too. specifically the angle at the pinion for the last u joint?

The double cardan joint can be disregarded; the two joints cancel themselves out (it's like a tiny, mini shaft on its own).

If you ever have a system with three single joints - well, one is going to be odd man out and you just have to live with it.

K

 

[Keith Seymore]

Seems to me I have seen driveshafts with un-equal angles at each end from the factory. Not much but some. I wonder if there is a certain level of allowable difference. Obviously it's important but the differences in the video were pretty pronounced for demonstration purposes. I imagine the further off you get the more pronounced the change in speed and it probably isn't a linear change.

Factory spec is less that 3 degrees for four link rear suspension; less that seven degrees for leaf spring rear.

This is because of the exaggerated amount of pinion nose wind up with a leaf spring suspension. If any of you have the opportunity to drive your truck without the pickup box on it - I highly recommend it. You will be surprised (I think) by the amount of windup during even mild acceleration and deceleration.

K

 

[Keith Seymore]

Summary: this is going to be blasphemous, and you will probably never hear anybody say this again - but the ideal driveline, from a torque transmission standpoint - would be perfectly straight, with zero degrees working angle at either end. But - you can't have that from a durability standpoint, because the rollers within the caps will not be rotating and they will brinnell into the cap races, causing a vibration. So - we like to have a degree or so to keep the rollers rolling and prevent brinnelling.

But it seems moot to me anyway, since with all the pinion nose windup and suspension trim height changes during use its not going to stay in that position for long anyway.

My $0.03

K

 

[MadOgre]

Summary: this is going to be blasphemous, and you will probably never hear anybody say this again - but the ideal driveline, from a torque transmission standpoint - would be perfectly straight, with zero degrees working angle at either end. But - you can't have that from a durability standpoint, because the rollers within the caps will not be rotating and they will brinnell into the cap races, causing a vibration. So - we like to have a degree or so to keep the rollers rolling and prevent brinnelling.

But it seems moot to me anyway, since with all the pinion nose windup and suspension trim height changes during use its not going to stay in that position for long anyway.

My $0.03

K

Sounds like your talking latest gen Corvette technology