Brake Problems

I have a 1976 280z w/ automatic transmission. I am the original owner. Recently my brakes got very hard. I could hardly stop the car. I drove home, parked the car over night. The next day I started the car up and the brakes went to the floor. I tried to pump them up and they still went to the floor.

From my experiences and reading on the internet, hard brake problems are related to the brake master vac. Brakes going to the floor are related to the brake master cylinder. I removed the brake master cylinder and after inspection, thought I saw some brake fluid inside where the brake master vac plunger goes. Based on conversations with a mechanic friend and the price difference between a new brake master cylinder and a new brake master vac, I decided to install a new brake master cylinder. I installed the new bench bled brake master cylinder, bled the brakes according to the FSM, and the brakes went to the floor when the pedal was pressed. I then removed my brake master vac, had it rebuilt, reinstalled it, re bled the brakes, and the brakes still went to the floor.

There are no leaks anywhere on the brake system. There has been no brake work done on the car for the last 3 years. The one way vacuum valve is working correctly. I know there are adjustments on the brake master vac plunger (the end that goes into the brake master cylinder) and the end that hooks to the brake pedal. The plunger end looks to be adjust correctly according to the FSM. The end that hooks up to the brake pedal has very little adjustment left and has never been adjusted.

Any thoughts???

Edited March 15, 201214 yr by BackDoorz