Hinge Joint Motor Force Units?

Hello, I am trying to make a 4 wheel drive with unity hinge joint motors. I am struggling with the fact that this is not as fast as what I used to use rigidbody.addForce. Is this in different units? If so, what would the scale factor be that is applicable.

I also have this issue where my drivetrain just flips over as soon as I start moving. As it accelerates it just slowly lift off the ground and soon uncontrollably spins the drivetrain.

Thank you... hope that someone can help me.