Double cardan rear drive shaft without SYE

[PatrickH]

Right now I have 4" blocks with 4*. Another 3 or 4* will get me there. I already have an assortment of shims.

 

[Blue85]

Everything I've have seen says that with a standard drive shaft is set to 6 degrees down. With a double CV shaft you point the rearend pinion to zero IE straight at the trans case.

For standard driveshaft (single joint at each end), the rear pinion should be parallel to the TC. The angle of the shaft is not part of the calculation.

 

[cuervo]

Great photos!! Explains it better then I could.

 

[PatrickH]

The angle of the shaft is not part of the calculation.

It is when the angle of the shaft in relation to the pinion/ output shaft approaches 15*!

 

[Blue85]

But you still want 15* in both joints. Yes, large angles cause vibes, wear joints faster, etc, but the best pinion setting is still parallel to the T-case (or a tick above). To get less than 15* you have to move the axle back, T-case output forward (i.e. SYE) or run less lift. By setting the rear angle to 0 for a CV, the pinion comes up, which reduces the total drop in the shaft and reduces the angle in the front (CV joint) as well.

 

[PatrickH]

But you still want 15* in both joints. Yes, large angles cause vibes, wear joints faster, etc, but the best pinion setting is still parallel to the T-case (or a tick above). To get less than 15* you have to move the axle back, T-case output forward (i.e. SYE) or run less lift. By setting the rear angle to 0 for a CV, the pinion comes up, which reduces the total drop in the shaft and reduces the angle in the front (CV joint) as well.

Yes, I understand all of this. Actually, you want the pinion a tad below the output shaft to compensate for vehicle loading and spring wrap.
I've been building and working on 4X4's professionally for 25 years. I was just wondering about the double cardan with reverse slip, as I've not personally run this setup before.
I do appreciate everyone's input!