leaf spring perch angle

[timopajala]

Hi, whats the correct way to weld perches and how to measure the correct angle? Someone said that i should hook the u-bolts and lower the car to ground, then measure the trans yoke angle and make the rear angle the opposite. Example if trans is -3 degrees down rear should be 3 degrees up? Does this make sense? Also its gonna be really hard to tack it in place under the car and make it centered like that but is that the correct way to do it?