67 front drum harmonic whine issue

[VOLZ1207]

What would be causing a harmonic whine under moderate to heavy braking? 67 all new wheel cylinders, lines, pads, has been bleed and adjusted (short pads on front). I'm thinking i need new front drums or resurfaced. Anyone ever run into this issue. Thanks for your time and info. Take care all.

[LONGHAIR]

You might try a very light turning pass across them to change the texture of the inside of the drums....but a harmonic vibration is pretty common with drums, that is the reason for the coils spring that wraps around the rim of some of the early vehicle's drums....and why the machine shop may put one on during the turning process. It can "ring" while being cut too.

[Rooster's 67]

make sure the drums after turning are smooth and don't show "chatter" or "threading". They can be caused by improper machining technique. Chatter will look like a diagonal pattern most times and threading is cause by too fast a feed speed during a cut causing what will look like threads of a bolt(all be it very fine) both can cause funky noises/vibrations during braking.
Like Longhair said if the spring is missing from the outside circumference of the drum you will very likely get harmonic noises.