I put the original wheels back on the other week. Since then I get an occasional squeak at low speed from one of the rear wheels and I'm sure its the disc. I have had the caliper rebuilt as a result of this but the squeak is still there. It only seems to happen when the breaks are warmed up. Could the disc of slightly moved position during the wheel change? Any other ideas?
Possibly just badly positioned shims. Take the pads out and give everything a good cleanup and lightly grease all the shims, clips and mating faces, with copper grease and then reassemble. Obviously its worth taking the disc off, cleaning and greasing the mating faces, whilst you are there.
If goes without question that the braking friction surfaces should be grease free.