The Stovebolt Site Forums The Shop Area Paint and Body Shop Painted Chassis Parts

I'm thinking it will depend on the part. You won't want much contamination in greased fittings where parts are intended to move. You also will not want to mar the mating surfaces of machined parts. I would clean them out with lacquer thinner, and avoid sanding if at all possible.

EDIT: for future reference put a thin coating of wheel bearing grease on the machined surfaces prior to paint. After painting they can be wiped out with a shop rag taking the grease, paint and all.