One problem using 2 rail cars on 3 rail Atlas track and turnouts I did not mention. I have found that, with the older Atlas 2 rail cars and using Kadee couplers, the couplers will lead the cars and their trucks through a diverging route but the wheel sets will not follow and will foul the guide rail, and this is due to excess lateral play of the wheel sets in the truck frames. On the worst offenders, I measured 3/16" of wheel lateral play. On the MTH 2 rail equipment that I run, the wheel set lateral play is only a few mm, and they do pretty well. All cars, at times, have problems with the Atlas frogs. My success rate running an entire 2 rail train through Atlas #7-1/2 turnouts on a diverging route is about 30%....not good enough.
While an investigation to determine what dimensions, if anything, work to make both 2 rail and 3 rail equipment compatible in this regard, it seems to me that on the 3R Premium equipment a better wheel material, and a more prototypical tread profile and flange size would reduce noise considerably. Everyone would benefit from the elimination of pizza cutter flanges and fast angle wheels on this equipment. My opinion.
