Interesting. So this technology eliminates drive line angle issues (within reason) all together? Transmission output shaft angle no longer has to be accounted for, pinion angle can be up or down (in relation to the then trans output, and within reason) and it doesn't matter?
That is correct. For this particular application, where the CVs are rotating at a relatively high speed (higher than they do in their place at the drive axles), the upper limit of misalignment is 9 degrees from center, so a total of 18 degrees. Less misalignment is always better because this reduces heat and consumes less power.
In the photos of the GTO bits above, you're using a CV + U joint shaft. The trans yoke is fairly large diameter - any issues with clearance to the floor or bracing? I thought there was more angle change at the rear so why the CV at the front instead of the rear? Could it be either and still achieve the same results? What application would necessitate CV's at both ends?
The CV slip yoke is only slightly bigger than a 1350 size yoke. The O.D. of the front CV is 4.25". You can see some scuff marks on my floor, those were from the 1350 slip yoke when I was trying to position it as high as possible to minimize my front operating angle. Of course depending on your transmission, the slip yoke will be in different places, and the available room may vary due to under floor bracing, etc...
From the factory, engines are positioned slightly down to the rear and at stock ride height the driveshaft also points down from the trans to the rear. This results in a small front operating angle, and small rear operating angles.
With my car (and many others) the engine still points down slightly to the rear, but since ride height has been lowered, the rear axle is now riding higher in the chassis. This causes the front operating angle to increase. This condition can't be cured by altering the pinion angle. Altering the pinion angle can make the front and rear operating angles equal and opposite, as is required for smooth operation, but it can't make the angles smaller. Which is ultimately what causes the high speed vibrations that so many of us experience.
With the set-up in the GTO, I set my pinion angle such that it points slightly down in relationships to the driveshaft angle, like this: \ /
Because the rear pinion angle is dynamic under power, you want to to oscillate from this \ / to this - - to this / \ (exaggerated here of course). This assures that the rear u-joint operating angle is as small as possible as it moves around under power. Hope that makes sense...LOL
The single CV solution is totally acceptable and it works, but ideally you want a CV in the rear as well. The rear u-joint will still speed up and slow down as it rotates and without the front u-joint to cancel out the motion it isn't ideal. But since the operating angles of the rear u-joint are so small (no more than 1 degree from center) the oscillation is not felt. Using a rear CV ensures that the driveshaft does not have any harmonics as it rotates.
Again, this is not a cure all for all high speed vibrations. This is a solution for a vibration that is caused by an excessive front operating angle (and subsequently a high rear operating angle).
When I installed the GTO shaft, there were no solutions for the rear, otherwise I would have done it (I may still upgrade in the future). With the Cougar, the rear pinion angle will change a lot because of the leaf spring rear suspension. My goal will be to set the transmission position and the pinion angle such that the front and rear operating angles are as small as possible, yet without concern for them being equal and opposite. As long as I don't exceed the 9 degree limit, the shaft will operate very smoothly. If you look under any modern high end front engine RWD car, you will see this type of driveshaft being used.
Have a look at the latest Dana (Spicer) catalog. This type of CV is called the Rzeppa joint.
Hope my explanation is clear.