I recently had the front discs redone in my '63 Valiant and after a few hundred miles later a clunking sound emerged from the front. It was intermitant and would stop when the brakes were applied. After putting it on a rack at the shop and removing the wheel, it was easy to diagnose. If you slightly rocked the entire assembly by hand the you could see the edge of the plate of the pad bump against the caliper. It moves about 1/4 inch. They put some grease at the point of contact and that stopped it. But I'm sure that's temporary. This never happened after the disc conversion so I'm wondering if anyone else has had this experience. It doesn't affect the brakes but is mildly annoying.

What kind of disk system do you have?
The pads on late-A "slider" disks the outer pads should be fit to the caliper by tweaking the tabs. Photo and text about halftway down THIS
Sloppy pad fit might cause something like what you describe.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

I have the four piston type.