The 14 bolt Cab and Chassis axle I have has 13" x 3.5" brakes for dual wheels. Drums I think are
NAPA # NB 4401652 Napa # NB 4401651 is a single wheel drum with the same brake size.
To use the single wheel brake the backing plate will need about a 1-5/16" spacer between it and the bracket on the axle tube. Which gives this much more room between springs and backing plate.
One problem may be the two different drums in question mount differently. The single wheel drum is intended to slip over the hub, and the dual wheel drum is installed on the hub then the whole assembly is installed on the axle.
I expect that the single wheel drum can be installed first just like the dual wheel one was.
Which leads to another possible solution, and so far I think the best yet.
Use the original dual wheel drum but install it on the outside of the hub. Preliminary measurements are promising. The ID of the drum is 4.5", same as the pilot on the hub for the wheel.
The inside of the drum is machined flat to an 8" diameter, which will accommodate the wheel mounting surface on the hub.
If this works the backing plate needs about 1.75" spacer, and as much room is made between the springs and backing plates.
Added benefit is easy brake work by removing wheel then drum (without removing the entire hub and drum).
A small downside is the wheel gets moved out another 1/4" or so because of the thickness of the drum flange. And note that it's not a problem to loose the pilot diameter on the hub (now used to locate drum) because the single wheels are stud centered (not hub centered like duals)
I've already got a hub and drum off, I'll try swapping drum to the other side.
Grigg
