I have Kelsey Hayes power disc brakes in the front and stock drums in the rear. When I apply more than light pressure (like for a normal stop), the brakes lock up and I start sliding. There have been times when I had to really hit the brakes—tires screeching—and I still couldn't stop. My classic car enthusiast friends say this is normal for a 58-year-old braking system, but that doesn't seem right to me. This can't be normal, can it?