The NASTRAN constraint set acts on the DOFs in the output coordinate system (not the definition coordinate system). If you are aligned with the global coordinate system, you just constrain the out-of-plane translation. If you are not aligned, you will need to define a local coordinate system, reference this coordinate system as the output coordinate system on the GRID card(s), then constrain the out-of-plane translation.
To get the correct answer I had to create a reference node within the local cordinate system and connect it to my original node. I then set the spring constant really low for the plane I wanted motion in and really high for the planes I didn't. Just constraining the motion to a single plane didn't work probably because it messed with the moments. Thanks for the help though.
