Join Date: Aug 2018
Location: Two locations in NH: One near Concord, the other at the 45th.
I'm sorry I misunderstood the nature of your noise. I was imagining the ratcheting to be a low-register thumping of an irregularity in the tread that would go away at speed. So its a slow metallic click, not a rumble? I still can't imagine how rotating tires could cause that. The timing may be coincidental.
If the vehicle is jacked and the tires spun manually do you still get the noise? That might help with finding the location. Maybe your mechanic has already tried that -- I'm just fielding an idea.
Obviously you've done some research. Have you tried the Jeep Patriot and Dodge Caliber forums? Those vehicles are siblings to the 1st gen Compass, so you might investigate those forums, too.
This is a long shot but I remember with my '74 Cherokee that backing up in a zig-zag pattern would solve issues with the Quadra-track system. Maybe try it with and without the 4wd lock engaged? I have a 2nd gen Compass so I may not be much help with your 1st gen. If/when you get this solved, please post the solution for the benefit of others.