Originally Posted by 62champ
The aux springs will allow the truck to carry a heavier load without bottoming out on the primary springs. It also keeps the ride fairly stock without going over the heavier springs which will ultimately give you a rougher ride.
Be careful, however - if you want to haul heavy loads you will need to do more than get aux rear springs.
I have ridden in a 1 ton pickup made in 1950...gives a new meaning to the term "rough ride." Owner joked that if you drove the truck over the shadow of a power line over the road you could feel it in the ride...
Most aux rear springs do not touch their mounts until the main spring is deflected, usually 1 to 2 inches. This means that you do not loose any of the ride quality empty. As for the 50's truck, they all rode rough. This is because of the shorter stiffer springs used, on newer trucks they have a longer spring that helps absorb the slight bumps on the road without compromising the load carrying capacity.