the test Loco lineup:
1) 4-8-2, IHC, C&O Mountain (made in Solvenia). Has a very very mild case of cookie cutter wheels.
I have quite a number of these locos as they run very well, they were relatively cheap, etc
2) 4-8-2, Bachmann, C&O Mountain. Has modern small flange wheels.
3) 4-8-4, Bachmann, Northern Santa Fe, I have 3 of these but was not able to get them operational for this test
4) 4-8-4, Broadway Ltd, Northern Santa Fe,
5) 2-10-4 BLI ,T-10, C&O Blueline model
6) 2-10-4 BLI, T-10, C&O paragon 3 model
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As I had mentioned above, "I'm already surprised at a few initial trials without any shims".
Peco Short Y turnout (no shims)
The first test I made was with the Peco short Y. My initial thoughts were that this turnout would give me more problems than it did, primarily because of its relatively tight radi. Turns out it give me some sporadic problems with 2 of the engines.
Naturally the 2-10-4 locos did derail most of the time, but surprisingly ONLY on the diverging route that bears off on the opposite direction from the curve leading into the Y. ( I term it counter-turning). If the loco continues in the already curving direction, there was no derailments, even when continuing on in a 22" radius curve.
The Backmann 4-8-2 mountain loco was another problem. It also derailed when 'counter turning', but did not when continuous turning. I suppose this was due to its very fine wheel flanges? I definitely need these to work well as I have at least 3 of these locos (I really like these flying pump, vandy tender, C&O mountains).
Another welcome surprise was the BLI 4-8-4 that did not show any signs of derailing on this turnout, nor many yet to be reported,...even with its fine wheel flanges.