Need your thoughts guys, i have a 69 Bee with no brakes. The brakes are manual, disc front with rebuilt calipers, rebuilt drums rear. Replaced the porportioning valve with one off of my 69 coronet parts car that i drove a month ago. Installed a new master cylinder today, replaced the rear lines with coronet parts car lines, new rubber lines front, installed new bleeder valves on the drums. The pedal is spongy and goes to the floor with the touch of a finger. I bought a pheunmatic bleeder, bled all lines but i am getting tinny amounts of bubbles still. If you pop the cap on the master cylinder and pump the brakes when you let off its like a water spout front and rear. The only way the brakes will work is if i pump the hell out of them. I have verified the porportioning valve is installed correctly, there are no visual leaks, while pumping or with the bleeder sucking fluid threw. I am a pretty mechanically inclined person and i am loosing hope, please help if you can.

 

If you can find or make some fittings to Block/seal off the master as a starting point should have a solid pedal. that would mean the master is good, Then add the rear and then the front
Or remove the proportioning valve

Another possibility if there is still air ??? use something to depress the brake pedal and leave it depressed overnight..

 

I will try blocking it to test the master cylinder we did block the front and back seperatly, pedal never got hard, we have tried 3 master cylinders and 2 proportioning valves, how do you remove it and what would you be testing? Also what would leaving the pedal depressed do? Im thinking there is a pin hole somewhere sucking air but if that were the case it should be leaking when pumping the pedal no?

 

Holding the pedal down is kind of like gravity bleeding, allowing the air to rise

 

If that dose not work.... Try a power bleeder

 

I fought my brakes when I got my 70 RR going, had a new NAPA master cyl. on it and it just kept loosing pedal and fluid. I tried 3 different master cyl. on it and still had the same thing. I could not find any fluid under are on it any where. I was doing all this by my self. I got some help one day and was under it when I found a drip on one of my lines, it was leaking where you couldn't see it. Tightened it up and bled one more time and have had a full pedal since. So you have to check and double check every thing never give up you'll find it and it will be something simple. Good Luck! Ronnie in Okla

 

Been using a pheunmatic bleeder

 

Thanks Ronnie, thats exactly what im thinking, maybe a hidden pinhole. With the pedal being this soft and still getting air after about 20 bleeds do you think there would be a noticable leak or.could it be very minor?

 

The very FIRST thing is shoe adjustment. So go 'round and adjust all the shoes up TIGHT until you cannot turn the wheels.

Then bleed the brakes and see what sort of pedal you have.

I don't like gravity bleeding. I just don't. I've dealt with several situations where POSITIVE PRESSURE in a system is a good thing. Gravity bleeding puts NEGATIVE pressure on the system

How "handy" are you? I've built pressure vessels---you are only talking about a few psi, here, plumb the pressure vessel into a front or a rear line at the master, and force fluid through to the wheels, to both force out air and to flush out debri/ old fluid

Make sure the master has been bled. With the system bled and the shoes tight, you should get a high, stiff pedal, and with the pedal held down hard (someone watching) you should get spurts back out of the master. Careful here, you can get fluid all over painted surfaces.

Then back off the shoes until the shoes scrape

 

Did you replace the rubber lines.

 

What he said!! It is called BENCH BLEEDING

The master cylinder will take about 40 full compressions to fully bleed it !

You must bench bleed, recirculating the fluid back into the MC with the (usually included fittings and plastic tubes) submerged in the reservoirs fluid.

 

Thanks guys, i can tell you know what your talking about and im going to follow your instructions and seewhat the outcome is!

 

So tonight we blocked off the master cylinder and got a hard pedal. Left the front capped adjusted the rear shoes until the wheel wouldnt turn, bled the lines and no pedal. Blocked the back bled the front individually and no pedal. Would you replace all the lines or replace the porportioning valve? Keep in mind we have replaced the valve once with a used spare we had?

 

Try putting the old one back in....

 

Well we just figured out that the front calipers were on backawards, the bleeder valaves were on botto so we had trapped air up top, doesnt explain the back though, guess we will replace the valve and see if that fixes it.

 

Brakes are fixed guys, previous owner hd the calipers on the wrong side upside down, we rebuilt them but assumed they were fine, thanks so much for all the help.

 

perfect !!!!!

 

i have found that some discs brakes will bled by gravity, no pumping needed, SOME

 

Agreed... I've done it a time or two on the older stuff....