My '67 Chevelle has brake problems. The car came with the brake problems when I bought it. Disc brakes front, drum brakes rear, with power brakes.

The brake pedal nearly goes to the floor. Pumping the brakes doesn't do much for it. The front calipers do grab the discs and stop them from turning. But the rear shoes do not expand at all when the brakes are applied. I checked with the drums off.

All brake lines are recently replaced. No leaks are evident at the rear wheel cylinders or the front calipers. There does seem to be a small drip between the master cylinder and booster. But the brake fluid does not seem to drop when the car is parked.

When bleeding the brakes, a powerful squirt of fluid comes out at the front wheels. Much less comes out at the back wheels - more like a dribble than a strong squirt.

Even after repeatedly bleeding the lines at all four wheels, there are no brakes in the back and the pedal remains very spongy.

I thought of replacing the master cylinder, but would rather not just start replacing parts without knowing what is causing the problem.

Any help will be appreciated!!

This is from a post by Black69 a few day ago: I would guess you need to bleed your master clyinder:

From Black69

I just did this yesterday and the instructions that came with my cylinder stated
"Fill the reservoir with clean brake fluid. Check and make sure the bleeding tubes are fully submerged. Use a dowel or phillips screwdriver then slowly depress the plunger to the bottom of it's bore. Let the plunger return very slowly under it's own pressure. Fully depress and release the master cylinder plunger, in slow, even stokes, 10 to 20 times. "Top off" the brake fluid as needed to keep it full. Depress and release the plunger in a series of short strokes (about 1/4 of the full stroke length).
While doing this, tap the bottom of the master cylinder casting with a small wrench or bar to free any trapped air bubbles. Bleeding is done when plunger strokes no longer cause air bubbles in the clear tubes." Hope this helps. Dave

One very common mistake that folks make, is they bleed incorrectly. if you haven't done so you should bleed starting with the right rear, left rear, right front, left front in that order. Then I would check to make sure your pads are adjusted correctly on the rear. They should touch the drum slightly when spinning the wheel.


Rocky