"sinking" vehicle engine

[Vilespring]

I have made a custom engine for one of my land vehicles. the engine is tank like, but doesn't have the tread on it. the engine is 2 "treads," and each tread is 2 willy wheels, one front, one back, and 3 sherman dummy wheels between them.

To the point, the vehicle is okay empty, but when I enter the vehicle and try to drive it, the wheels collapse and the vehicle bottoms out. When I get out, the vehicle goes back to normal. What in the blood happened?

[Swaffy]

Check your springs. The spring strength and the damping.

[Vilespring]

The 4 drive wheels have a strength of 50, and a damping of 5. the mock wheels have strength of 0, and damping of 0. The vehicle has a mass of 2500.

[Swaffy]

Check the wheels for a collision mesh,
check to see if the wheels are attached to the engine and not the vehicle,
I'm out of ideas.

[Vilespring]

Well, it was really just the order the wheels were attached. The left tread right tread thing messed it up. Adding each wheel individually to the engine fixed the problem.