Excerpt from "Racing the 260Z" that I wrote when I sold the car. Maybe it'll help:

· Drum Brakes-These need to be adjusted every 30-45 mins of race time but are easily taken care of. Jack up the wheel and spin it. The brake should lightly drag on the wheel. If not the brake pedal probably won’t feel good and the rear braking will be weak. To fix it adjust the shoes out to increase drag by turning the star adjuster with a flat blade screwdriver. Look at the brake drum and you’ll see a 1” diameter hole. Rotate the wheel to approximately 6 oclock and you’ll be able to see the star wheel adjuster. Use the screwdriver as a level to turn the wheel and increase the brake drag. You’ll probably need to remove the wheel and drum once to learn how it all works before you can do it without removing the wheel and using the access hole.