Drum Brake problem

66 coronet,10" drums,manual,have been working fine for last few years but now have a problem..The pedal started going to the floor,so I bled all the way around.the shoes still have meat on them and are all adjusted so that the wheels move about a 1/2 turn when spun off the ground.My big problem is that when the pedal goes to the floor,slowly,sometimes I can pump them and I have pressure again although the pedal will still go slowley to the floor when depressed.On a lot of occasions now I must use the side of my foot to raise the pedal as it does not always return .When I bring the pedal back up I have presure again.The pedal does not always go to the floor.It is worse as the brakes heat up.I have some ideas,just need some input.Thanx.Mitch

Your master cylinder is going bad. It's bypassing fluid between the seals internally. Just replace it and your good to go.

That is it. Master cylinder is worn. One of my '67 Furys was doing the same thing. I was able to buy a new one at NAPA.
John

Never done a MC before although this one looks pretty straight forward.Any good pics somewhere of detailed look at MC and removeal prcedure..Now this MC is one of very few AM parts as the owner before me put this on in 1992 so the frts and rear would be on seperate lines .Napa says they have one but the pic looks like the original round one...Any suggestions at where to look in the norther suburbs of Detroit for one.
Can't get my pics to DL.. .There are 4 bolts with the nuts inside the car.What about the pushrod to unhook.Any thing special I should know.Thanx.

Sounds like he changed to a dual master.That car had a single.If it has drums all around get one for a 67 or 68 C body with 4 wheel drum.Bench bleed it install and bleed the system.If its power brakes they just un bolt from the booster.Manual you have to unbolt the rod from the pedal and reinstall the new rubber on the old rod and seat it in the back of the laster.Rocky

I changed my 66 Newport from the single to dual sump mc. I bench bled with silicone fluid, installed and bled the right rear until the fluid color changed, left rear, right front and ended with the left front. My paint is original, but I still don't have to worry about fluid leaks hurting the paint. I also planned to add disc brakes in front, so I installed a disc brake mc right from the start. Works fine with the front drums.

So I think I found the MC,A-1 Cardone.Anybody ever here of this..It looks the same,I will find out monday.Behind the brake pedal is a spring and cap with a small clip that looks like it clips around the shaft into the MC..Hope I explained this OK.Hope the pic works.it dosen't..Should I try and bend the clip a little as there is a groove in the shaft that it looks like it goes around..

Still can't post a pic.It says no file larger than 500000....
it worked fine a few days ago...hhhmmmmmmmm.
Well I got the pic to post..See the cap,is there a special way to clip that on the notch on the MC shaft.And should the spring be depressed.....

So how important is having that spring compressed and that cap properly seated to the MC shaft.

None of that stuff looks correct. Where did the spring and cap come from?

There's an internal spring for that.

The spring to push the pedal back up should be inside the master cylinder, not on the rod outside of it..
The new/ rebuilt master will require you to install the stamped boot retainer in place of the small metal arrow finger that the power brake cars use.
Here is a pic of the only thing you should see inside the car..

SOOOOOO.I have driven the car a few times and up until sunday the brakes were working fine,not spongy,hard pedal,even had to brake hard a few times and all was well.So I started thinking..
I took off the drums to check the shoes better and I found that all the shoes,frt & back all had a small crack going down the center of the shoes.So today I am replacing all the shoes as the drums are still pretty smooth and clean.Could this be causing my pedal going to the floor,especially when the brakes get hot.What might cause the cracking..
Also,What is the differance between bonded and riveted shoes besides the obvious.Is one better than the other..Was trying to find info online to research this..Thanx.

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There's an internal spring for that.

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This past winter I installed a new MC in my 65 Coronet. Got it from NAPA. It too has that exterior spring and works great. It's a new one, not a rebuilt one.