Well sorry Jimlin I beg to differ the Reyco 4 spring suspension uses all the same principles with some changes like torque rods for front to rear alignment instead of eyes in the springs other than that it still uses and equalizer between the front and rear spring. We have used solid steel spacer blocks on many fuel trailers to match hitch and drawbar heights for customer tractors. Likewise we have added spacer blocks on tandem duals for height adjustment for hotshot rigs and yet pavement pounding rv's somehow are subject to magically higher side torque values and road abuse. If your sub frame only weighs 100-125 lbs then the fab guy is using material that is too thin to stresses that have been described here. I would not recommend more than 2" on an RV suspension and there are different heights of spring hangers available. Larger U bolts can also be used by simply using upgrade plates and spring caps. Increasing the size of the center bolt is also an option. Sorry but I just won't accept that some of the needed upgrades are impossible because some never seen it or dunnit trailer dragger says so. RV dealers are full of these goofs selling product to people and then walking away leaving the owners looking for solutions.
