I am attaching a Librands luggage rack (with sidescreen space) to my new 2025 plus four. At least I'm trying to. It's a 5 wheel car. Does the original "lipped" disc go over or under the rack? Either way, I can't turn the T-bar down enough to tighten the wheel/disc/T-bar package. It all just rattles. Do I need to grease the threads or even add more washers? There's one washer already but still leaves a space.

You can't beat a man at his own game.