Measuring Driveshafts

I have a custom diff and a C4 suspension under my 71. How do I decide how long to make them? Sure I could put tape across each flange and measure center to center and be done. But when I put the suspension at ride height and I adjust the lower suspension arm all the way in the rotor is then and only then perfectly vertical. So I would have no adjustment tighter than vertical. When I crank it out the bottom of the rotor pushes out. Obviously, vertical is fine and you would only add more camber. But do I want to pigeon hole myself to vertical at full adjustment in? Could I make the driveshaft (upper control arm) longer to push it out? Or would I put a lot of pressure on the system by doing so? I tried to put a wedge in the suspension and it was difficult to move the top out very much?
What do you think? Then how much??
Thanks,
Charlie

I'm not following your description completely but the halfhsaft is indeed the upper suspension member. Since you do not want to run negative camber anyway, what you do it, you set the lower strut to it's shortest length or thereabout (you can the stock cam eccentric adjuster?) then you set the wheel for 0 camber (vertical) and measure the center to center u joint distance of the halfshaft. That would be a good length to get or just a tad shorter. You will be able to adjust from 0 to a couple of degrees neg. camber from there out. It should be very difficult to wedge the suspension to change the camber setting, the whole vehicle weight is on there.

Correct

Twin_Turbo said:

I'm not following your description completely but the halfhsaft is indeed the upper suspension member. Since you do not want to run negative camber anyway, what you do it, you set the lower strut to it's shortest length or thereabout (you can the stock cam eccentric adjuster?) then you set the wheel for 0 camber (vertical) and measure the center to center u joint distance of the halfshaft. That would be a good length to get or just a tad shorter. You will be able to adjust from 0 to a couple of degrees neg. camber from there out. It should be very difficult to wedge the suspension to change the camber setting, the whole vehicle weight is on there.

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Your assumptions are correct. I meant the halfshafts and not driveshaft. I wasn't sure about the negative camber. I thought maybe it was better to run a tad longer halfshaft and use some of the abundant adjustment of the lower strut.
I will just zero it and go.
Thanks for the help!!!!
-Charlie

Make it a little shorter than zero, so that you have a little adjustment both ways around zero and the rest of the adjustment into neg. camber.