P15 brake pedal pressure

[mopar_earl]

Do I use any thread sealant on the brake line?

No! Everything is flared and seals that way. No sealer needed! Sealer and tape will only cause issues.

Earl

[Plymouthy Adams]

on flare fittings, the threaded section is only the jamb nut..

[cerick305]

It appears the boot on the master cylinder is leaking when I squeeze it. I assume this is how air is getting in the lines... Anyone know where to get a replacement?

[Don Coatney]

The boot holds no pressure. It is a dust cover only. The master cylinder inner seals must be leaking.

 

Is the master cylinder assembled correctly?

 

[dpollo]

Raybestos MK 143

[cerick305]

It appears that I didn't have the cup that's I between the piston and stop. Not sure if that would make it not seal properly. I orders the attached kit. Hopefully this will do it.

[cerick305]

With it all apart and when I manually press the piston into the master cylinder, slight amount of residual brake fluid is on the outer (atmosphere) side of the piston. I think the piston gasket isn't holding as well as it should be. At what point to I replace just the gasket with kit I purchased or replace the entire master cylinder? I haven't priced out master cylinders but I'd hate to put it all back together and find out the master cylinder had scratches or something that was allowing fluid to pass piston ...

[mopar_earl]

Buy a new master cylinder, don't risk brakes! Especially if you're keeping single circuit.

Earl

Edited April 17, 2016 by mopar_earl

[cerick305]

Would it be difficult to switch to double circuit?

[mopar_earl]

I installed an ECI dual circuit master cylinder kit on mine. Great kit, at least for my 52. They will need to know if you have fluid coupling or not and if your clutch pedal is on the master or on the frame.

Earl

[soth122003]

If you pull the floor to get the M/C out, then why not hone the M/C bore replace the seals and give it a whirl. The only thing you be out is about a 1/2 of labor.

 

Joe

[cerick305]

Ok, I replaced the master cylinder and rebled the lines. All is working great. Thanks all for your help. However, one more question.

I noticed with old master cylinder and new cylinder the metal plug (cap) on top doesn't appear to be sealed. When I was bleeding the cylinder on new one, I held upside down and small fluid leaked out. This is the case for new one and old one. So when I was completed, I put a couple layers of Teflon tap on cap to seal it off. My mind of thinking says it needs to be completely air tight. Then why wouldn't the cap have some sort of gasket?

[TodFitch]

Ok, I replaced the master cylinder and rebled the lines. All is working great. Thanks all for your help. However, one more question.

I noticed with old master cylinder and new cylinder the metal plug (cap) on top doesn't appear to be sealed. When I was bleeding the cylinder on new one, I held upside down and small fluid leaked out. This is the case for new one and old one. So when I was completed, I put a couple layers of Teflon tap on cap to seal it off. My mind of thinking says it needs to be completely air tight. Then why wouldn't the cap have some sort of gasket?

 

You need a breather hole in the top of the cap so that air can come in to replace the fluid pushed into the lines.

 

Gasket on the cap is to keep too much fluid from sloshing out as you drive down the road. Having a gasket there does not mean you don't need a breather hole.

[cerick305]

Currently cap is sealed without a breath hole. But seems to brake fine. Not sure f it needs to be changed.

[James_Douglas]

There is a little pin hole in the cap, on e old ones it is on the side in a flat.

 

On the subject of hoses...

 

Some years ago I had a new rear hose on the '47.  I had the car up on a lift doing the muffler and I did a walk around.  I noticed that the new hose, from NAPA, had a large bulge in it.  if I had not done the muffler I would never had seen it in the next 6 months with likely very bad results. 

 

After that, I purchased Earls adaptors to go from inverted flair to AN and then I purchased DOT approved Russell stainless braided hoses.  Since I run a single master cylinder in all my cars, I did not want a hose to go. 

 

On a different subject on the shoes...if you can find someone with a shoe arc machine.  I have one and it makes a big difference if the arc of the shoe match's the drum. 

 

James.

[TodFitch]

. . . On a different subject on the shoes...if you can find someone with a shoe arc machine.  I have one and it makes a big difference if the arc of the shoe match's the drum. 

 

Agree that having the shoes arced to match the drums makes a big difference. If you don't have access to a shoe arc machine, you can get a roll of sticky back sandpaper and do the job pretty well: Line the inside of the drum with a strip of sand paper and then rub the shoes inside the drum on the sand paper until you have uniform contact. That will arc the shoes to the diameter of the drum minus the thickness of the sandpaper. The paper I used was a bit thicker than it ought to be for the exact right arc but it made a huge difference in being able to properly adjust the shoes and in the final pedal height and feel.

[James_Douglas]

Tod, You can always drive up for lunch and use mine...

[TodFitch]

Tod, You can always drive up for lunch and use mine...

 

A bit of a drive now as I've moved 450 miles south. I happen to have an Ammco brake shoe arcing machine too, but got it after I did the sand paper trick on my shoes.

 

The new house is in a beach town where the parking is about as available as it is in your neighborhood. Up side is that it is walking distance to the beach and more shops and restaurants than you can shake a stick at.