I have been dealing with a brake problem for almost a month and I have some clues I would like to share and get some input.


Can't seem to get a hard pedal on power disk front/rear drum. I have noticed that the front lines have tiny bubbles when I am bleeding them. Can't bleed them out completely. I crimped the rear hose and front hoses and have a solid pedal. I released the rear and still soild.

The problem must be with the fronts because when I release those the pedal goes soft.

I am think I have have a small leak in the front lines which are only two years old. I have brake fluid on the bottom of the subframe under the master & thoght it was from sloppy bleeding. Maybe my new metal line wore a pinhole in them. Does this make sense?

Replaced calipers& master again this weekend & everthing is basically new.

Thanks for the help

Your getting air in someplace. If teh master cylinder was bled properly, it has to be a fitting or small hole in the line. I would clean all lines/fittings, have a buddy put slight pressure on the pedal, and check all to locate the leak.

I had the same problem with my '67 with factory front disk brakes. It turned out the problem was the front brake hold off valve located just under the master cylinder. I removed the valve and formed a short line from the master cylinder to the distribution block and was able to bleed the front brakes with no problem. I did this over a year ago and the system remains tight. The odd thing was the hold off valve was not leaking fluid but sucking in air. I purchased a rebuild kit for the valve but have not installed it yet. The brakes are working fine with out it.

Having a good pedal after pinching the hoses suggests the problem, if it is air, is likely confined to below where the hoses were pinched for the test. That's not a guarantee, but thats how it usually works. Air getting sucked in above that point would likely still get sucked in even with the hoses pinched, although with the reduced stroke, it may not. Bypassing the metering valve as suggested might help you, if you have one. it might help to know more specifics about your system.

I hate to say this, but it happens sometimes.. make sure the bleeders are at the top.

I dont know your method of bleeding, but if you are using a hose on the bleeder into a jar, or using a vacuum bleeder, sometimes air can get sucked past the threads and make it look like air in the lines, when there may actually be another problem. Even a mismatched pushrod can sometimes make the 'hose pinch' test come out like that. You might try gravity bleeding for a while, close the bleeders and test the pedal. If it is still soft, open a bleeder and see if an air bubble comes out. If it is hard on the first hit, pump it a few times and see if it gets soft... that would be air getting sucked in without a major fluid leak. A fluid leak will cause the pedal to sink as the fluid escapes.