Help with mysterious brake noise, '78 550

[Guest]

On my '78 550, the front wheel makes a clacking sound in time with the wheel revolutions when the bike is cold. Seems to come from the brake caliper. The sound goes away if I lightly apply the front brake. I'm running the stock rotor, caliper and pads (replaced last year). The caliper and pads move freely, and the pads don't drag when the brake is not applied, but I haven't rebuilt the caliper.

I can sometimes hear a trace of the sound in the shop, if I elevate the front end and turn the wheel slowly, but I cannot determine the source. I can't feel any roughness or burrs on the rotor, and nothing else is rubbing or striking when the wheel turns.

Anyone have any suggestions?

[hampshirehog]

Does the caliper wobble on the pins? They, or the holes they fit in, could be worn. Also worth checking to see if it's the speedo drive as that's not far away.

[chuck hahn]

Worn out or missing orings on the carrier pin, slightly warped rotor, loose outer pad retainer screws.

[ChicagoBob]

Thanks all. I'll check those items.