[67Mustang Al.]

Thanks . i wasnt aware of that . I guess its like mixing engine oils and coolants.
The local guy at the brake centre sold me "Super Dot 3" about two months ago. I will go back to him for a set of seals. The American master cylinder looks almost the same as an Aussie 1971 Ford XY Falcon tandem unit.
Yes there is a large rear cup seal on the second piston which could be called "Mushy"
Before i imported the 67 into Aus. it sat in a guys ranch in Pinon Hills .California. for 6 yrs. I dont think the fluid would have been changed even though the master cylinder was new.
thanks. Happy new year in Louisiana for tomorrow
. Our new years eve is tonight here.
Cheers and thanks for the info.
Al.

[OLNOLAN]

You too Al, If you rebuild your self don't forget to hone the cylinder a little bit to give the new seals a surface to seat in. Slick bore and new seals leak every time with me. Tryed it more than once, Duh! olnolan

[67Mustang Al.]

Originally Posted by OLNOLAN

You too Al, If you rebuild your self don't forget to hone the cylinder a little bit to give the new seals a surface to seat in. Slick bore and new seals leak every time with me. Tryed it more than once, Duh! olnolan

We are on the same wave length there Nolan. Just finished running the brake cylinder hone down the bore. All i need now is a new kit of seals to go in it. i am guessing most places will be shut in town now for the new yr. Cant be beaten by this. I have solved a zillion other problems of after market mustang parts that dont fit. Just another brick in the wall.
Appreciate your tips. I have had a lot of help from guys like yourself from the other side of the planet. I would not have got this far for sure without. The mustang is similar to our early Fords here in a lot of ways, just annoying at times. I AS they say here, have a shrimp on the bbq.
Cheers
Al.

[67Mustang Al.]

Originally Posted by OLNOLAN

You too Al, If you rebuild your self don't forget to hone the cylinder a little bit to give the new seals a surface to seat in. Slick bore and new seals leak every time with me. Tryed it more than once, Duh! olnolan

Just a question for you Nolan. See the bit of wire in each hole there. They go straight through to the bore and are clear in each side of the cylinder.The second hole in each side is blank, goes nowhere. Air pressure did nothing into the hole so you can see with a drop of brake fluid sitting there its going nowhere. Any clues there. Maybe just a drilling mistake at the plant where they were made.???? I hope the holes that go through to the bore have been drilled in the right position. Cant find a brand on the master cylinder casting anywhere for i.d. of it.
Cheers
Al.

[67Mustang Al.]

Just a query for someone with trouble shooting experience with master cylinders.
Having gone to four places to find a set of cup seals for this"new" {sitting too long in the car) master cylinder , i am unable to get any brake fluid out of the secondary piston outflow after slow pumping with the screwdriver as a pushrod. Seals are on correctly and the primary piston is pumping as it should when i push the screwdriver into the end of the piston with plenty of fluid out of the line.
The only thing i can think of is that there is something missing which has the location of the secondary cup sitting on the wrong side of the filling port. Any clues gurus. Cant afford to pull any more hair out.
Al.

[cobalt327]

Have you checked to be sure there's no physical blockage of the port to the reservoir?

If you had an '80-up M/C, the valve shown circled below might be stuck.



Your M/C is an older cast iron unit, so it won't be too likely to have anything other than possibly a residual pressure valve in the port itself.

[67Mustang Al.]

Hi 327 .The cast iron unit has a port hole in each side of the reservoir which are clear through to the bore. I checked the outlets of each with a piece of wire and they are clear as well. The only valve in the system is a "2psi blue willwood" non return valve fitted directly in line out of the master cylinder on the rear part or secondary side only. I am going to try and bench bleed the thing with plugged outlets as i saw some guy demonstrating on you tube. He depressed the pistons slowly and waited for air to rise up.
Its a puzzle.
Al.

[technicaltom]

http://www.rodsnsods.co.uk/forum/tec...-give-up-25639 . Hi I hate to see anyone stumped. so maybe the information in the link above might shed some light on your dilemma , Have a read of it, theres also some good insight to more Hot rodders.

[cobalt327]

Originally Posted by 67Mustang Al.

I am going to try and bench bleed the thing with plugged outlets as i saw some guy demonstrating on you tube. He depressed the pistons slowly and waited for air to rise up.

The last M/C I installed on my '80 Malibu used that method. Plugs were used to completely stop flow from the outlet ports, then the piston was depressed gently and not fully to the rear stop to expel air from the reservoir feed ports in the bottom of the reservoirs.

But the way you had yours plumbed to bench bleed above was correct, as long as it was leak-free and tight.

Is there a chance that you weren't pushing hard enough on the piston to overcome the resistance of the larger spring that separates the front and rear valves?

[67Mustang Al.]

Originally Posted by technicaltom

http://www.rodsnsods.co.uk/forum/tec...-give-up-25639 . Hi I hate to see anyone stumped. so maybe the information in the link above might shed some light on your dilemma , Have a read of it, theres also some good insight to more Hot rodders.

Thanks Tom. Had a read and it seems that he is still chasing the same problem. I am thinking of doing what cobalt suggests and see if the travel of the piston is depressing both springs and not just the primary or front spring.
Cheers.
Al.

[67Mustang Al.]

Originally Posted by cobalt327

The last M/C I installed on my '80 Malibu used that method. Plugs were used to completely stop flow from the outlet ports, then the piston was depressed gently and not fully to the rear stop to expel air from the reservoir feed ports in the bottom of the reservoirs.

But the way you had yours plumbed to bench bleed above was correct, as long as it was leak-free and tight.

Is there a chance that you weren't pushing hard enough on the piston to overcome the resistance of the larger spring that separates the front and rear valves?

Hi 327. Yes the connections were good without leaks. So i have bench bled it again, but plugged this time. The travel i measured was 11/4 inches until it bottoms out. I have fitted it back on to the power booster and i have purchased a vacuum brake bleeding kit to try and suck the possible air lock out of the rear chamber of the master. Like you said,i am not certain that the secondary spring is compressing enough to force fluid out. If this vacuum pump does not work then i will find a piece of 1 inch hard plastic conduit , cut a slot out of the side and set both pistons in it so i can see how far the rear piston is moving when i push the 1 1/4 on the front piston. From the section drawings i have found on tandem master cylinders the seal has to be behind the filling port at rest and then travel past it to compress the fluid.
Cant let it beat me. No joy from Cal Mustang /LA where it was purchased originally. The receipt shows disc brake conversion kit. i assumed the master was the correct one with the kit.
Thanks
Cheers
Al.

[67Mustang Al.]

Well after fitting new seals to MC and bench bleeding, then refitting to power booster and still no rear brakes i decided to pressure test the rear lines with about 10 psi from the air hose. (SEE PIC) i heard air escaping and found that a "banjo" connection was leaking although the bolt was tight. THe end of the flex line to the rear caliper has anOFFSET SEE PIC. i had fitted it the wrong way around and it would not seat evenly on the copper washers. So it LEAKED. No wonder it would not bleed to the rear.
I have just bled the whole system, from long to short using a vacuum bleeder called an "AIRBOY" fitted to each caliper bleed screw in sequence Great piece of gear and "NO LEAKS"
I have no idea how a mustang stops with 4wheel disc brakes, or standard brakes either but now i can fit the steering and hopefully plant the engine and drive this thing.
Well its been a frustrating exercise and thanks for all the tips to help me eliminate one thing at a time. Cant be beaten.
The pedal is now firm.
Cheers
Al.

[OLNOLAN]

Well don't that just piss you off. Thats one of them things that happen. Glad you finally figured it out. Should stop on a dime now. Keep up the photos, I like SEEING what folks are working on, way better than talking. olnolan

[67Mustang Al.]

Originally Posted by OLNOLAN

Well don't that just piss you off. Thats one of them things that happen. Glad you finally figured it out. Should stop on a dime now. Keep up the photos, I like SEEING what folks are working on, way better than talking. olnolan

Its slowed me down for sure. Had to walk away a couple of times and pull the door down. It was easier to rebuild the 347 than play with these brakes. Just got to keep on poluggin away until this thing is on the road.
Cheers.
Al.

[technicaltom]

Delighted to see that you solved the problem,And glad you shared the results as im sure it will help another Hot Rodder in the future , Dont ever give up