When I installed the new Maddox drum brake I found that the cover plate (on which the brake shoe is mounted) ended up positioned about 3/8th of an inch too far outboard leaving a big gap between the plate and the drum and leaving a potion of the shoe that hung over the edge of the drum.
I found the same problem on both of the hubs I installed it on – an old Hugi and a newer White Industries Daisy. I removed an axle spacer from the White Industries hub and still had the gap. (The axle on the White Industries hub is larger so this was after removing the bushing from the cover plate.)
My solution was to put a spacer between the brake drum and the hub so that the plate fit where it wanted to on the axle and the drum came out to the appropriate place on the shoe. The instructions that came with the brake give a minimum gap (so that the actuator arm doesn’t contact the drum) but they don’t specify a maximum gap. It doesn’t make sense, however, not to have the entire shoe inside of the drum and the smaller the gap (up to the manufacturers specifications) the less dirt and water will get inside of the brake.
I had some steel washers with a half-inch center hole. By luck their exterior dimension was just right for the large-flange hubs I was using and their thickness was right to properly position the drum. (I actually had several thicknesses to choose from and I was able to pick ones that put it right where I wanted it. My task was thus only to grind out the center hole so that it fit on the hub (and didn’t damage the threads.)
Here’s what the end product looks like:
Here it is again with an un-modified washer for comparison
Here is a shot of the mounted drum, showing that with the spacer the end of the threaded portion of the hub is flush with the end of the threaded portion of the drum (just like it was made for it.)
Here are a couple of shots with the cover plate loosely in place showing that the gap still exceeds the minimum set in the instruction manual.
Note – after all was said and done I took the bike into R&E with the Hugi wheel set mounted and asked them to do something involving the rear wheel. They found my spacers and realized that to mount a brake on that hub a third segment of the axle was required (omitted on my wheel set since it came without a drum brake.) With the right axle configuration no spacer was required… They graciously fabricated the missing segment for me and didn’t give me a hard time for my hack.