I wonder if you could explain (preferably with photos) gear shimming? If you're talking about taking end-play out of worms, NorthWest Short Line makes thrust washers in various sizes and thickness. They're bronze and made specifically for such work. They're also useful for removing side-play from other types of gears. If you need to shim a gearbox (increase the width of a split-sided one) or increase clearances for a bottom coverplate, brass shim stock is available in increments of .001". You can cut this material with a knife or scissors, at least in the thinner sizes.
Wayne
Those Kadee washers are hard pressed fiber, and will work fine as gear shims. In fact, Lionel used to make some of their O gauge motor gears from pressed fiber back in the 20's and 30's, and they held up very well as long as they were made properly.
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