HOrailroading

Here is a tip when assembling car kits.   Adjust the screws that retain the trucks (assuming that is how the trucks are attached - most better cars have this feature) so that the truck on one end of the car is fairly snug, but can easily swivel (but no rocking).    On the other end of the car, adjust the truck so that it will rock just slightly.   This will give your car a three-point stance, allowing it to travel smoothly over uneven trackwork, yet keeping it from unnecessarily rocking.

on rolling stock