Not a C3 expert but check U-joints, rubber snubber on the diffy, and although it usually does it just under initial load, may as well have a look at the swing arm bushings while you're there. Since it disappeared, doesn't sound much like any of these. Maybe it never comes back....
Ah yes... Brakes.... good call Murray... Had a Chevy truck once that had a broken brake spring. Easy to pull the wheels and check that too...
I agree with above re: brakes BUT maybe not drive over the climate protestors blocking the road.
It's difficult to describe. It was like an elastic being stetched and let go with a medium pitch clunk. Car has disc brakes so I doubt a stone would get stuck. I appreciate your thoughts and I realize it could be a lot of things. It sounded like it was coming from the rear of the car. I've considered the differential fluid and gears or a bad axle spline but I think those would be prevaIent at higher speeds and I don't see how they would self correct, also thought about a trim ring or centre cap flexing or a loose lug nut. One of life's great mysteries at the moment. I was hoping perhaps someone had a similar experience. These things are difficult to diagnose when they're no longer acting up. The joys of motoring!
