Sometimes when the drum gets put back on it catches on the lugs and doesn't seat completely. Then when you put the wheel on it feels tight, but it isn't. Driving it a bit lets the drum seat farther down, then the wheel's loose - could be the source of the clunk.
Check the lug nuts to be sure they are tight.
If the adjuster is too loose, the entire assembly rotates inside the drum and has that clunk. It's usually, but not always, accompanied by a low pedal too.
A common mistake is switching the adjuster from side to side - then when you back up instead of tightening, it adjusts looser.
That's why it's important to do one side at a time - it's easy to put them on the wrong sides.