Auto body repair & detailing: sanding and painting, proper adhesion, dodge truck

Question
have recently repaired all the dents and dings on my 2005 dodge truck, which I'm told has a base coat/clear coat system on it. have had limited practice with auto finishes but am going to repaint it myself. my question is do I need to dand and reprime the entire vehicle, even where the paint is still good, or can I just sand the entire vehicle for proper adhesion? also, tried wet sanding the good clear coat areas with 400 grit, but seems like that would take forever to get a uniform surface, any suggestions as to how to more quickly ready the existing good areas on the paint before applying the base coat? thanks for your time...mark

Answer
Hi Mark,

When sanding an existing finish to prep for paint I recommend using 500 to 600 grit wet. You basically are just trying to de-gloss the finish. If there's not any chips or scratches that should be more than adequate. If you plan to use a sealer then you could go with 360 to 400 grit wet. I hope this helps out.