Quote Originally Posted by 85cj7 View Post
When building a drive shaft what is a good percentage for compression and extension of the splines? Say you have 6" of total spline engagement in the shaft. At ride I would think you would want a min. of 50% engagement (in this case 3"). A previous shaft I built had 75% full engagement at ride height but that seems like a lot. I guess this question has a lot to do with your related suspension travel.
I don't know that this is right or wrong, I take the distance yoke to yoke of the truck (say 36"), then I take the slip of the driveshaft (say 6"), subtract 1" from the slip (so now 5"), divide that in 2 (2.5"), then I make the shaft compressed length the yoke length minus the previous number (36" - 2.5" for a compressed shaft length of 33.5"). There is no magic to that, just what I do.