once rotors over heat they warp but what about a brake drum ? I have a set that look near new that were painted and the paint is burnt. Will they be ok or should I buy new ones?
I don't have a good answer for you, but I do recall watching the stock car races in the seventies, when some of the cars still ran drum brakes. You'd see some of the drums glowing red hot through the slots in the wheels at night, so it seems like they could take a lot of heat and still be functional, but can't say for sure if it's OK for a street application.
Are new drums available in that size? If so I'd say play it safe and toss them for new ones. But that's very unscientific and just my 2 cents...
On the wear surface of the brake drum it will show discolouration (slight bluing) or hard spots if the drum has been overheated. I changed lots of brake drums on taxis that had been too hot. It really shows up when you try to turn them on a drake lathe. The cutter wont cut the hard spots from overheating very well.
Paul