is it normal for the n scale rolling stock to shake going down the rails? the box cars are worst,they vibrate and are not rock steady,it does not look too cool.when i had g scale rolled down the rails real smooth but they also have a lot of weight.i tryed adding weight inside the box cars but did not help much.Iam using atlas flex track with 22 inch radus.i was hoping for a more real looking train.are the HO scale trains more solid on the track.Iam pulling this 8 car train with a atlas sd60 diesel and it runs real smooth.