Spring perch angles for new axle

[Speedwagon]

Hey everyone- I want to check my math on setting up a new axle.

Swapping out the 99 axle in favor of a 2011 10.5 with an E locker on my van. The angles I measured on the van, after zeroing to the frame, are: trans flange 5, driveshaft 10, pinion flange 7. Single cardan shaft. Which should mean I need to rotate the new axle down a little to match the front operating angle of 5, plus 1-2 for axle wrap, yes?

If I measured a difference of 11.7 from the pinion flange to the spring perch, then I should need to set the difference on the new axle at around 8-9, correct?

 

[tacobronco]

Yes, you are correct. The pinion angle should be 1-2 degrees less than the transmission or transfer case angle.

Regarding your second paragraph, in principle you are correct, but I wouldn’t permanently weld the spring perches with the axle off the vehicle. Typically you would assemble the axle tube, perches, and leaf springs with no welds and the u-bolts just snug, drop the vehicle down so the springs are loaded normally, then check/adjust the pinion angle before burning in the perch welds.