Having now moved the spring perches to fit the wider spring spacing on an AD truck... The clearance between springs and the brakes leaves very little room for u-bolts, and approximately zero room for bleeding brakes.
The original brakes to the 14 bolt C&C axle are 13x3.5" (few exceptions may exist) and have a deep offset drum, remember these axles came with dual wheels on them.
Bendix # PDR0619, GM # 18006042, NAPA # 440-1651, is a drum with same 13x3.5" brake size, bolt pattern, yet with 1.25" less offset. Photo attached of the two side by side. This drum comes on many 1 ton pickups (both 2wd and 4wd), vans, and step vans from 1974-1999. The shallower drum works by spacing out or relocating the backing plate flange on the axle tube 1.25" closer to the wheel so the original backing plate and all brake hardware fits in the shallower drum. Now plenty of room between backing plate and springs for bleeding brakes.
This drum fits great in single wheels and also fits real nice in the original 18" dual wheels (photo attached), and also plenty of room for 19.5" dual wheels. Probably won't fit 16" dual wheels.
Couple ways to move the backing plate: --Machine 1.25" thick spacers with both pilots and counterbores, see drawing attached. (thumbnail is real faint) --Reuse, purchase, or make new square flanges to weld onto the axle tubes but 1.25" closer to the wheels. --DO NOT use washers or pieces of pipe as spacers, not safe and strong. (see thumbnail below)
The new backing plate flange should be 4-11/16" from back side of hub where the drum mounts. Photo attached of original location for the deep drums, at 5-15/16".
