So I just got my first bike, and I guess by dumb luck I have picked a very nice reliable bike. Took it for a spin and it rode really nice, and it came with a certificate of safety, but after a couple of days driving it, now it has this really weird quirk with the rear brake. The best way I can explain it is it feels very similar to when you’re driving a car with a stick and try to put it into gear without using the clutch. A very rapid grinding sound. You feel it in the pedal, and you can hear it. Sounds like you don't know how to shift the bike and everyone turns their heads. Doesn't happen every time I use the rear brake, and I can apply the brake things will be fine, but as I down shift then it will start to grind. As for my brake pads, I am pretty sure they are done, for the nut has been tightened all the way down and the spring is totally compressed. I took it to this motorcycle shop that's been around for a long time and the old guy there thinks it maybe more than just a need for new pads, and told me to open up the drum to find out what is exactly wrong. I am hoping before I do that someone may have experienced a very similar problem and can steer me in the right direction. Thanks for any info you can provide. 1979 CX500.