Looking at one of the modification guides it suggests that brakes are impacted by the stiffness and height of suspension upgrades and that the rear brake proportioning valve (BPV) control arm should be adjusted accordingly. I've got the highest rated coils for my bus plus a four inch lift at the rear. Not sure about how the load carrying capacity of the spring affects the adjustment, but going on lift alone it suggests adding four inches of bracket to the arm. I've been running a 2-inch bracket for ages. Is anyone implemented this mod with a bracket > 2 inches, assuming you have a lift > 2 inches. The lift increase was taken from the before and after measurements supplied by the suspension fitter.
How does a hard spring rate affect the adjustments?