Appreciate all excellent responses. At first, I was suspecting something wrong with my newest Lionel SW8 Conrail Legacy switcher, but I'm seeing that it's actually related to the cars themselves, and there is no universal "one size fits all" easy fix, but to start analyzing each car and adjust the weight on the problem ones. As noted before, the heavier vintage Lionel cars- like the #3472 Automatic Refrigerated car (20oz), the 3461 log car (12 oz) , and the #3469 Automatic dump car (15oz) are no problems, so I naturally place them near the front. And, I assume I don't have to add any weights to them, correct?
I think I'll go with the Harbor Freight 1/4 and 1/2 oz self sticking weights, but do I really have to make ALL my lighter weight all plastic cars (like my Menards) 15 oz?? That's almost a POUND for EVERY CAR! Or, do I simply start adding weights, a little at a time until I reach stability over the switches in both directions? I have some all plastic Menard flatbeds that are actually no problem, believe it or not- although I'm hesitant to raise the speed. Should I still add weights to them?
