Part of the rig Moving the whole body

[dthecoolest]

Make sure the root part is correct, similar to this other post:

Motor6Ds acting weird

The part which rotates depends on the root part of an assembly, by default it should be the bigger part. Maybe create an additional part that represents the root which doesn’t move depending on how you want to control it. You can adjust it by changing the root priority and to debug you can use the :GetRootPart function of a part and print it out within the command bar.

And this one

Problem on Rigging Custom Model

That’s odd, usually it’s the Humanoid RootPart that’s connected to the part which rotates the entire body which is what you seem to be doing. Have you tried changing root priority, and setting the primary part of the model to the root part?