I’m getting to the end of my rope here with my brakes, not sure where to check next for the problem. 1970 Cougar, Power Disc Front and Drum Rear.
I’ve got a new power booster that’s correct for my year, new master cylinder, new lines going to the distribution/warning block, the front has new rubber lines going to 67 or 68 calipers and rotors, and the rear has new everything. The only old parts are the hardlines and the distribution block. I went through another master cylinder and assumed it was the problem since I was ending up with low fluid in one reservoir and high in the other so I thought it was leaking between them.
I bench bled the master, reinstalled, and with plugs in both holes it felt very firm, couldn’t even get the pedal down an inch. I hooked it up to the lines, and then I hooked up my pressure tank bleeder and got it pumped up to 15psi and it held for at least half an hour before I started to get to work on it. I bled all the wheels, starting from the furthest and making my way closer to the master cylinder, I got no bubbles from any of them, since it had been bled before. With the pressure tank still on and still at 15psi, I was able to turn the front wheels by hand without much effort. I disconnected the bleeder and took it around the block and it has no brakes for 90% of the pedal travel, then the last 10% it gets enough to slow it down a bit from about 30mph.
When I installed the master cylinder I adjusted the pushrod further out than where it should be, and then put the master on and off and adjusted the rod until the rod didn’t push the piston in the cylinder when the master cylinder was tightened to the booster. Is that a fine way to do it, or do I need to adjust it so that it slightly pushes the piston in?
I bled it again today, I ran a half quart of fluid through each wheel, over a few minutes with the pressure bleeder. I got maybe 5 or so bubbles from the rear passenger wheel cylinder, but nothing at the other wheels. Master cylinder was level, the system held pressure, and I got through the 2 quarts of fluid completely fine. Still nothing. I have messed with the adjustable block that changes pressure to the rear brakes, and completely tight or loose and anywhere inbetween hasn’t had much difference.
So I’ve got a system that can run fluid through all the lines, no leaks or blockages, and it holds pressure indefinitely. I’ve bled 2-3 quarts of fluid through it over the past few days, no bubbles. The master cylinder was very firm when it had the plugs in it, so it wasn’t leaking through anywhere.
The only hint of a problem I had was when I pumped the brake pedal a few times with one rear bleeder open, it hardly moved any fluid, however I thought that was because I had a messed up master cylinder, which has since been replaced. I haven’t gotten a chance to check again, but I assume the same is true of this new master cylinder.
Any advice as to what could be busted? The only things left that I could think would be the distribution block or adjusting the rod out further, but I thought that not letting the piston fully decompress was bad and would cause your brakes to stick, and I’m not sure how the distribution block would cause this problem unless it was leaking. Any help would be appreciated. Thanks.
