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OK, here is my attempt to explain how we shimmed and checked the rear wheel bearings for correct preload (if anything I say here is wrong, feel free to jump in and correct me, I am learning here too. I think it helps me too, to try to explain this):
A photo of the ds rear wheel bearing where I've attempted to show that the outer race is sticking out further than the inner race (in between, you can see the retainer which is holding on the rollers). We've cut some shims out of 0.005" thickness brass shim material and placed them such that when the backing plate presses up against them, it will also be contacting the outer ring face and pressing it in a little.
My 444 manual describes how you can check that the backing plate is pressing up against your shims and the outer wheel bearing race face, by checking the "axial shaft end play" with a dial indicator. Pulling the shaft in and out and measuring the displacement is 0.0008 - 0.0047". This ensures the preload on the bearings is correct. Here's a pic of us doing that.
Without any shims at all, the backing plate presses up against the bearing outer race with the maximum amount of force. This makes the preload on the bearings the highest--excessively high. Some preload is good (it maintains alignment and prevents the rollers from slipping on the races), but excessive preload is hard on the bearings. And in this case, it likely wiped out my bearings (they weren't shimmed at all when I diassembled them, and are showing signficant wear).
New rear drum brakes installed, everything cleaned up and painted:
This was the before pic of the exploded wheel cylinder mess (I think I said master cylinder exploded before, I meant the wheel cylinder exploded):
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