I went to take the vette out today , and as I was starting it up I got a surprize. The brake pedel went to the floor.I checked the brake resisviour itwas 3/4 full in the front section,however the back section was bone dry.I drove the car two weeks ago with no probelms.

The rear section of the reservoir goes to the rear wheels. I would check the rubber lines first. If they're ok, may be your calipers. Do you know how old they are?

If there are no leaks, or fluid running down the wheels from a caliper leaking, your master cylinder is leaking into the booster...
Loosen the two nuts that hold the master to the booster, and pull it out a couple of inches, and see if the rear is wet with brake fluid. If so, you'll need to rebuild the master, or replace it.
Also, it would be a good idea to get as much fluid out of the booster as you can. A turkey baster with a long hose attached will do the job. You can go thru the hole where the plastic vacuum check valve goes to suck the fluid out of the master. That's a LOT easier than pulling the booster out, and turning it upside down!
hth

Hey,  Rick, sorry to hear about the trouble you're having. Remember, I just had to have the master cylinder and booster replaced on mine right before the Chip Miller show last November.  Hope you get it worked out before spring! Mines in the shop right now getting the valve seals done. Let me know how it works out. The bakes on these cars do have their unique quirks!

To add to what Joel said, sometimes the master cylinder leaks past the piston, so you don't see an external leak.  The only real test for that is to plug the two outlet holes, and push the pedal.  It should be rock hard, and not fade no matter how long you hold it.

Larry

That's the mystery I don't have a booster,because I don't have power brakes.Today I crawled under the car and looked at the wheels there was nothing.Everything is dry,then I checked the inside under  the dash again nothing.Strange.

If the rear segment of the master was "bone dry", there has to be a leak there somewhere....

WOW!!! That's a tough call. Brake fluid loss with NO SIGNS of fluid, ANYWHERE!!!. C'mon, there's gotta be more you're not telling us. It's gotta show somewhere, even the bowl should look wet. Otherwise, there wasn't any fluid in the rear bowl to begin with. Brake fluid doesn't evaporate that quick, if at all.

   That why it's a mystery,one of the guys at work had a good idea. check to see if the fluid ran into the frame. I have to wait for a little warmer weather to check it. And no I did not leaving anything out ;I went to put the car in gear ,stepped on the brake and nothing.

                               Thanks Rick