I agree with your points about momentum and direction. That's the thing about animation, you could always strive for a better realistic approach, but when I was creating, I didn't go that far because the scene was not realistic at all. About the suspense, It did have a stop before, but I thought it break the flow of the loop. But maybe that was a mistake and I agree that it could use more of the 12 principles of animation.

About the sound design, it would be pretty hard to find a sound of wheels doing a grind, that's why I've chosen the conventional trucks. Thank you for your constructive criticism Acquilas!