Leaf spring width on 1/2 ton pickups remained at 1 3/4 inches until the introduction of the two inch width on the Task Force 1/2 tons in mid 1955. The early narrow springs worked well considering the engine horsepower and weight limitations of the 1/2 tons. The two inch springs became standard equipment on the rear of the 3/4 ton in 1946 but their fronts still remained the smaller size. This is because the increased weight carrying ability of the 3/4 ton is mostly felt in the rear. Only 1 ton and heavier were totally without the 1 3/4 inch springs.
With the abuse given pickups in the early days (poor roads, overloading, and almost no lubrication), the springs have held up well. Most mid 1955 and older 1/2 tons continue to operate with their tired original narrow springs.
In today’s world a new variable exists that puts even more demands on these small springs. It is the increased horsepower of later model engines. No problem if these trucks, converted to more powerful engines, are driven as if they still have their original six cylinder. However, problems arise with jack rabbit starts with or with a heavy freight load. Most of these Advance Design 1/2 ton’s with transplanted V-8’s have had their original closed drive shafts replaced with open systems. The replacement axle housings are clamped to the 1 3/4 inch rear springs. When heavy acceleration is forced on these modified trucks, the axle housings try to rotate due to the extra torque. Much of this movement is held in check by these narrow springs. They just weren’t designed for this. Breakage and permanent bending can occur.
Don’t push your 1 3/4 inch rear leaf springs beyond their limits. If you demand fast acceleration with your V-8 1/2 ton, convert to later model 2″ or 2 1/2″ springs. Check specialized suppliers, including Jim Carters Truck Parts (part # HP580), for add-on kits.