Its called side bearing clearance. Some times this is needed to keep the car from excess lateral movement but also can in our scale cause problems due to most folks not having the best of track work. One needs to examine the car and see where the wear pattern is occurring and make the adjustments.Later RJD
Thought I might see you at Perry next year, since you were not in sight for the show this year. Guess that's a bust... What a bummer!
Anyway, I've changed all my heavies to six axle trucks without any problems. Probably not prototypical but what the heck? Some of the heaview are early Korean grey-box items and some are new ones in the yellow boxes. You may have to do some easy engineering for the latest versions of the heavyweights. There is a constant note of caution about such a conversion but it seems to come from those who are not careful with their trackwork. I never had any problems either at shows or on my own layout. Of course my heavyweight passenger cars run only on 20-foot diameter curves and that may have something to do with the way they stay on the rails.
You've missed some four-axle heavies, probably because they were first class Southern railroads. The Louisville & Nashville, as far as I know never had six-axle heavies even for the Pullmans and the diner. The West Florida Railroad Museum at Milton, FL has four heavies on a permanent siding. One was a coach (now used as a museum office and library) and one was a diner that has been fully restored and is always in use for occasions. The heavies have their original four-axle trucks. The other two coaches have a storied history (also four-axle trucks) in that they may have been part of the train that took Fat Boy to the West Coast. Southern also kept to the four-axle model, as far as I know, although there may have been later modifications--not likely. That is what prompted me to comment about prototypical appearances since I have converted thirteen Aristo-Craft Southern heavies to six axle.
Bob Member, West Florida Railroad Museum Member, Emerald Coast Garden Railway Club, Milton, Florida
I converted all of my heavyweights to 6 wheel trucks. I was lucky enough to find someone who wanted to convert their 6 wheel trucked heavyweights to 4 wheel trucks so we just swaped. Maybe you should post an add in the classifieds here