Are any Parts of the following carriages Anchored?
Have you used a HingeConstraint between the carriages?
What force are you using to drive the train carriages, and is this in all of them or just the first one?
I’ve got a place that I made for someone to help show them one way to make a very simple train. It may help you out as well:
Train Experiment.rbxl (39.8 KB)
There’s a VectorForce in each carriage. If you select both the VectorForces you can change the value of the force in X or Z (I can’t remember) but leave the Y value as negative because this seems to keep it on the track. Start with 500 for both, and steadily increase it to see how the train acts. I think I got it up to something stupid like 40000 before it jumped the tracks.