[SCOTI]

It doesn't seem quite so simple in reality. What about if the front requires a different amount of air psi for each side??

I get adjusting preload, but it seems there would be WAY more to it on a street based 4-bar set-up vs. that race oriented 4-link. Typical street air suspension 4-bar set-ups w/poly type bushings @ each end aren't as adjustable (most only allow adjustment @ one end) & they're definitely not going to easily rotate to know if there's pre-load before making any adjustment.

When I did the 4-bar for my dually, I made jigs for the upper bars length (& lowers) to know each side/all 4 were equal/exact. I then installed everything & measured for square. I tweaked as necessary for getting things perfectly square. When they did the alignment, one thing I was worried about was the rear thrust angle & the 2 techs that did the alignment were impressed w/how tight/close the thrust angle was where I was afraid I might be off.

The alignment went w/o issue. But, my truck requires 10psi split up front & 20psi split out back. Also.... it's on opposing sides (pass front requires more psi; drivers rear requires more psi to be dead equal @ all 4 corners as measured @ the wheel opening lip (measurements validated pre suspension swap as well).

Thoughts?