A couple of thoughts on the ride quality of passenger cars:
- Part of it is track. You can't get a good ride when the track is rough. We went from Los Angeles to Minneapolis on a through Pullman over Union Pacific to Omaha, and on the CMStP&O (Omaha Road) across Iowa and Minnesota. The ride was not as smooth on the Omaha Road, but I can understand why. I drove the highway that parallels the route, and it was still 90-110 lb rail on light ballast. Same car, two different ride qualities in the same trip, due to track quality.
- Part of it is trucks. Many improvements in the design of passenger car trucks occurred over the 1937-1965 period, which coincides with the production of lightweight, streamlined North American passenger cars. Some railroads upgraded the trucks on their passenger cars and some did not. Thus, the Coast Daylight, rolling along on the original 1937 Pullman-Standard "Challenger" trucks was very dependent on the condition of the track, whereas Union Pacific and Santa Fe cars, riding on late-design trucks, were more forgiving of irregularities in the track.
