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Single circuit to dual circuit
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wizard
Posted 2020-12-15 1:00 PM (#606752 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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It's always the same procedure Todd, start with the wheel cylinder farest from the m/c - in a dual circuit that would be the front right lower wheel cylinder, front right upper wheel cylinder, front left wheel lower wheel cylinder, front left upper wheel cylinder, rear right wheel cylinder and rear left wheel cylinder. Naturally depending which port is using for front circuit.

If you adjust the brake shoes to full contact (blocked wheels) it will be easier to bleed out the eventual air.

Do my measuring test before you start to bleed. That will tell you if there's any air in the circuits.
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Todd
Posted 2020-12-15 1:20 PM (#606755 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Sven: unfortunaly it's too late for the test, I had to start over. During the last bleeding, the fluid in the master was used up and it drew in air. s**t happens. But i will do the measuring if i have to pump again at the second try. I will now set the brake shoes to full contact before bleeding.

I've been thinking about an important thing. It affects the external residual pressure valve for the front port: On the picture you can see where I have placed it. I suspect it is too far away from the master - because: when I install the brake line at the master port, there is of course air in the brake line between the master and the residual presssure valve at the beginning. If I now press the brake pedal and release it again, this air is sucked back into the master, because the way to the residual valve is too long. The residual valve must be installed directly on the master port. And you can certainly help me: I need an adapter with a male 9/16 - 20 "connection (into master) and a male 3/8 - 24" (into residual valve). Do you know where I can buy something like this? Is there such an adapter?

Or do i think wrong with my theorie?

Edited by Todd 2020-12-15 1:32 PM
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Powerflite
Posted 2020-12-15 1:45 PM (#606757 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Another common issue is the residual valves look like they come well seated and sealed. That often isn't the case. You need to remove the pipe threaded connectors and re-apply them with teflon tape to seal them well.
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Todd
Posted 2020-12-15 1:49 PM (#606758 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Good thought, I'll seal them beforehand.
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Todd
Posted 2020-12-15 2:31 PM (#606759 - in reply to #606752)
Subject: Re: Single circuit to dual circuit



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wizard - 2020-12-15 1:00 PM

If you adjust the brake shoes to full contact (blocked wheels) it will be easier to bleed out the eventual air.


You mean set the shoes to the fully released position Sven?
https://youtu.be/oVCb0TE0lMI

See at minute 4:00.....

Edited by Todd 2020-12-15 2:32 PM
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1960fury
Posted 2020-12-15 3:14 PM (#606763 - in reply to #606755)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-15 1:20 PM


I've been thinking about an important thing. It affects the external residual pressure valve for the front port: On the picture you can see where I have placed it. I suspect it is too far away from the master - because: when I install the brake line at the master port, there is of course air in the brake line between the master and the residual presssure valve at the beginning. If I now press the brake pedal and release it again, this air is sucked back into the master, because the way to the residual valve is too long. The residual valve must be installed directly on the master port. And you can certainly help me: I need an adapter with a male 9/16 - 20 "connection (into master) and a male 3/8 - 24" (into residual valve). Do you know where I can buy something like this? Is there such an adapter?

Or do i think wrong with my theorie?


It is not too far away, but of course the closer to the MC the better and of course you have to bleed the system again after the instalation of the residual valve so I don't get the problem.
All residual valves I have ever seen are tapped for 1/8 NPT threads.
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Todd
Posted 2020-12-15 3:35 PM (#606764 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Yes you're right. But Wilwood sell them with inverted 3/8 - 24 adapters to directly install the brake line.
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wizard
Posted 2020-12-15 4:01 PM (#606766 - in reply to #606759)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-15 8:31 PM

wizard - 2020-12-15 1:00 PM

If you adjust the brake shoes to full contact (blocked wheels) it will be easier to bleed out the eventual air.


You mean set the shoes to the fully released position Sven?
https://youtu.be/oVCb0TE0lMI

See at minute 4:00.....


The adjusting cam is an excenter Todd, so fully backed off will be locked wheels as well. Try and check
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1960fury
Posted 2020-12-15 4:02 PM (#606767 - in reply to #606764)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-15 3:35 PM

Yes you're right. But Wilwood sell them with inverted 3/8 - 24 adapters to directly install the brake line.


So wouldn't it be more logical and easier to search for, or fabricate a 9/16-20 to 1/8 NPT adapter? Also cleaner looking and a connection that can leak less.

Maybe you can just tap the 9/16 MC tube nut (if there's enough meat) and use a male/male 1/8 NPT to 1/8 NPT connector?
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Powerflite
Posted 2020-12-15 4:05 PM (#606768 - in reply to #606767)
Subject: Re: Single circuit to dual circuit



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I'm not following what you are saying Sid. All connections go to 3/16 line - even at the master, so how does what you are saying help anything, or is even possible to do? I also wouldn't want that long residual valve sticking out of my master.

Edited by Powerflite 2020-12-15 4:07 PM
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wizard
Posted 2020-12-15 4:14 PM (#606769 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Also Todd, I don't think that you have air in the system, you confirm that you have a rock hard pedal on the second sttoke. Adjusting the brake shoes to full contact means that ther will be no lash, so first stroke still might be low, but thereafter you should have the same height every time you try the brakes If you get this condition with low pedal on every stroke, then the displacement is too low.
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1960fury
Posted 2020-12-15 5:10 PM (#606770 - in reply to #606768)
Subject: Re: Single circuit to dual circuit



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Powerflite - 2020-12-15 4:05 PM

I'm not following what you are saying Sid. All connections go to 3/16 line - even at the master, so how does what you are saying help anything, or is even possible to do? I also wouldn't want that long residual valve sticking out of my master.


Why do you want to run a 3/16 line between the MC and the residual valve when you can attach it directly to the MC? They ain't that long and It still looks better than a valve in the middle of a brake line and you can use a 90° adapter.
In my car it is attached directly to the prop valve as desribed with a male/male NPT connector but I will change it eventually and move it to the MC.
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1960fury
Posted 2020-12-15 5:19 PM (#606771 - in reply to #606768)
Subject: Re: Single circuit to dual circuit



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I know such things are considered a "No-No" when you work on brake systems, as it is 9/16-18 thread not 20, but it will work anyway. I am a safety neard. Maybe you have to run a 9/16-20 die on it and of course you have to grind off the AN cone.

https://www.ebay.de/itm/Gewindeadapter-1-8-NPT-zu-Dash-6-90-schwarz-...
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samstrader
Posted 2020-12-16 10:11 AM (#606789 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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Todd, I sure enjoyed and learned from the video you posted showing how to bleed and adjust the brakes.
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Todd
Posted 2020-12-16 12:51 PM (#606799 - in reply to #606789)
Subject: Re: Single circuit to dual circuit



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Thanks samstrader. Yes....TECH ist the best of the best. Always ask Tech - he knows :)
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1960fury
Posted 2020-12-16 3:06 PM (#606807 - in reply to #606767)
Subject: Re: Single circuit to dual circuit



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1960fury - 2020-12-15 4:02 PM

Todd - 2020-12-15 3:35 PM

Yes you're right. But Wilwood sell them with inverted 3/8 - 24 adapters to directly install the brake line.


So wouldn't it be more logical and easier to search for, or fabricate a 9/16-20 to 1/8 NPT adapter? Also cleaner looking and a connection that can leak less.

Maybe you can just tap the 9/16 MC tube nut (if there's enough meat) and use a male/male 1/8 NPT to 1/8 NPT connector?


I checked and yes, the MC tube nut is big enough. So you can simply tap it and screw the residual valve directly to the MC with that:



(NPT-elbow.jpg)



Attachments
----------------
Attachments NPT-elbow.jpg (113KB - 17 downloads)
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dplotkin
Posted 2020-12-17 10:12 AM (#606836 - in reply to #606212)
Subject: Re: Single circuit to dual circuit


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Todd:
I posted on the linked thread "spongy brakes" concerning the same problem I had with a 1960 F with front disks and stock drums using a drum/drum master. The drum/drum master will fit under the booster and I have this setup working well in my 61 Plymouth Savoy with later Mopar B body rear drums and GM single piston calipers. Because it worked in the Plymouth I thought it would work in the 300 F. No dice. Same as you - too much travel not enough juice.

Finally employed the taller but shorter Bendix disk/drum master for a 70 Imperial. I cut .700 from the top of the jar & threaded in two screws to hold the lid on. This master is a one inch and an eighth bore and has sufficient volume. Pedal travel is still longer than I would like but it is acceptable.

Try that master - no reason why you cannot use a disk/drum master on a drum/drum setup. Just use a 10 pound residual valve in the front circuit. See the aforementioned thread where I posted photos.

Dan
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Todd
Posted 2020-12-17 11:32 AM (#606839 - in reply to #606836)
Subject: Re: Single circuit to dual circuit



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Hi. Thanks. I purchased a brandnew 1 1/8 bore disc/drum master and installed a 10 psi external wilwood residual valve in the line. The first try did not work as i wrote. But I'll try again. I will bleed the front brake circuit particularly thoroughly and see what happens. But not enough time at the moment. I'm sure I'll do it before Christmas. I won't buy a third MC. If it doesn't work this time, I'll give up. I will report...thanks!!

BTW...The OE line from master to the front tee was 1/4"....maybe that will have the necessary effect to feed the brake 4 front cylinders....maybe it is worth a try too...if 1/4" line will fit to the port of the MC...hmmm....will it fit? Worth a try or not?

Edited by Todd 2020-12-17 12:07 PM
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Todd
Posted 2020-12-17 1:42 PM (#606843 - in reply to #606807)
Subject: Re: Single circuit to dual circuit



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1960fury - 2020-12-16 3:06 PM

I checked and yes, the MC tube nut is big enough. So you can simply tap it and screw the residual valve directly to the MC with that:


Hmmm....how's about this adapter...would it also work? https://wabotech.de/ORFS-Einschraubverschraubung-UNF-9-16-18-AG-NPT-...
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1960fury
Posted 2020-12-17 4:05 PM (#606846 - in reply to #606843)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-17 1:42 PM

1960fury - 2020-12-16 3:06 PM

I checked and yes, the MC tube nut is big enough. So you can simply tap it and screw the residual valve directly to the MC with that:


Hmmm....how's about this adapter...would it also work? https://wabotech.de/ORFS-Einschraubverschraubung-UNF-9-16-18-AG-NPT-...


Yes, good find! But it would make the valve stick out. Since it is 9/16-18 oo it might need a little reworking with a -20 die but it is not aluminum, like the elbow fitting I posted, so it would be even safer.

Edited by 1960fury 2020-12-17 4:14 PM
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samstrader
Posted 2020-12-19 6:20 PM (#606889 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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I used this site to buy my 7/16 x 20 Tube Nuts. I went to the page that has Plugs and the BQ 162 is a 7/16 X 20 plug. Would this work? They also have 1/2 x 20. All of my fittings were 7/16 X 20.

Anyway, not sure exactly what you need but these people sure have a lot of this unusual stuff and I was very pleased with what I got from them. Fit perfect.

https://www.mfcp.com/product/fittings/automotive-fittings/plugs-caps...



Edited by samstrader 2020-12-19 6:26 PM
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Powerflite
Posted 2020-12-19 9:36 PM (#606895 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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7/16-20 was used on '55-'56, but the '57-up cars used 7/16-24.
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Todd
Posted 2020-12-26 1:49 PM (#607150 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Merry christmas to all. As for the conversion from the single-circuit to the dual-circuit brake - that's it, i quit! The second attempt didn't work either. Firm pedal only when pumping the pedal. Then if I wait a few seconds, I have to pump again. Even if i adjust the shoes to full contact.
Now I'm looking forward to installing the old single-circuit MC. I'm really looking forward to a firm pedal and good brakes, just like it was before.
Thank you for your involvement and help. I wish you all a happy new year! Thanks, Todd.

Edited by Todd 2020-12-26 1:50 PM
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wizard
Posted 2020-12-26 1:54 PM (#607152 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Sorry Todd, it's a drag after all the work and effort. At least, you confirmed that the displacement of the m/c is insufficiant in the tested ones.

Please make a post of the brand, article number and diameter here
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Todd
Posted 2020-12-27 4:10 AM (#607163 - in reply to #607152)
Subject: Re: Single circuit to dual circuit



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MBM Disc/Dum MC
MC5621
Cast Iron
Original Bendix Style 2225621
1-1/8" Bore
9/16"-20 INV & 1/2"-20 INV
10lb residual valve built in to rear port.
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wizard
Posted 2020-12-27 4:35 AM (#607164 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Thanks' Todd, I assume this is the last dual circuit m/c tested, what about the first one?
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Todd
Posted 2020-12-27 5:31 AM (#607165 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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Auto City Classic Drum/Drum Brakes
MC1323
Mopar Bendix Style RPB8001
Manual or Power Applications
1" Bore
9/16"-20 INV & 1/2"-20 INV
W/ Builtin internal residual valves

As for the single MC: Between MC and the tee there is a 1/4" line, i also want to replace, but i don't have the tool to flare 1/4" lines, so i have to order the line - flared with the correct fittings ready to install. The size of those fittings is 7/16-24 UNF (long 20 mm version) BOTH sides, am i right?



Edited by Todd 2020-12-27 9:14 AM
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56D500boy
Posted 2020-12-27 12:15 PM (#607175 - in reply to #607165)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-27 2:31 AM
Auto City Classic Drum/Drum Brakes
MC1323
Mopar Bendix Style RPB8001
Manual or Power Applications
1" Bore
9/16"-20 INV & 1/2"-20 INV
W/ Built-in internal residual valves


Todd: So something like this? Any idea where I could buy just the push-rod accessories? I am going to use a similar Raybestos MC36221 (as shown below):







Edited by 56D500boy 2020-12-27 12:19 PM
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wizard
Posted 2020-12-27 12:39 PM (#607177 - in reply to #607165)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-27 11:31 AM

As for the single MC: Between MC and the tee there is a 1/4" line, i also want to replace, but i don't have the tool to flare 1/4" lines, so i have to order the line - flared with the correct fittings ready to install. The size of those fittings is 7/16-24 UNF (long 20 mm version) BOTH sides, am i right?



I'll try to check this tomorrow Todd
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samstrader
Posted 2020-12-27 1:41 PM (#607183 - in reply to #601590)
Subject: Re: Single circuit to dual circuit


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I'm sorry it didn't work out Todd. You did great work I think and it is so frustrating when you can't make something work out after working so hard. I can totally relate to your frustration.

Thanks for posting everything because your lessons learned help us all understand how brakes work better and also helps our thinking when considering going to dual master cylinders. I think I'll just stay with my single master now even though I know a dual cylinder is a lot safer.

Sam



Edited by samstrader 2020-12-27 1:46 PM
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Todd
Posted 2020-12-27 1:57 PM (#607186 - in reply to #607175)
Subject: Re: Single circuit to dual circuit



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56D500boy - 2020-12-27 12:15 PM

Todd: So something like this? Any idea where I could buy just the push-rod accessories? I am going to use a similar Raybestos MC36221


If you still have your old single master, you can re-use both, rod and clamp/mounting, both fits to the new MC.

Sam: Thanks a lot Sam, there are all nice and helpful people here, fantastic forum.

Sven: thanks for have a look at the requested thread sizes

Edited by Todd 2020-12-27 2:02 PM
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56D500boy
Posted 2020-12-27 3:52 PM (#607187 - in reply to #607186)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-27 10:57 AM
56D500boy - 2020-12-27 12:15 PM
Todd: So something like this? Any idea where I could buy just the push-rod accessories? I am going to use a similar Raybestos MC36221

If you still have your old single master, you can re-use both, rod and clamp/mounting, both fits to the new MC.


Not if you change the pedal assembly like I am planning. (Needs a clevis at the pedal end like the original 55 Mopar PB/MC combo had).



Edited by 56D500boy 2020-12-27 5:10 PM
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Powerflite
Posted 2020-12-27 7:53 PM (#607195 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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You can get things like that at Summit.
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wizard
Posted 2020-12-28 7:52 AM (#607202 - in reply to #607165)
Subject: Re: Single circuit to dual circuit



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Todd - 2020-12-27 11:31 AM

As for the single MC: Between MC and the tee there is a 1/4" line, i also want to replace, but i don't have the tool to flare 1/4" lines, so i have to order the line - flared with the correct fittings ready to install. The size of those fittings is 7/16-24 UNF (long 20 mm version) BOTH sides, am i right?



Ok Todd, just checked; the 1/4" fittings are both male 7/16"-24 UNF and 3/3" (approx 20 mm) long will work just fine.
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Todd
Posted 2020-12-28 10:08 AM (#607206 - in reply to #607202)
Subject: Re: Single circuit to dual circuit



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Thanks so much Sven!
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Powerflite
Posted 2021-01-03 2:55 AM (#607350 - in reply to #601590)
Subject: Re: Single circuit to dual circuit



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I just finished bleeding the brake system on my '56 Fury with front discs, original rear drums & a 1.032" dual disc brake master. It has a solid, high pedal now with about 1.5" of travel. The only issue is the pedal is firm even with the rear bleeders open. The rear brake hose must have plugged itself off, but was open enough to allow the air to escape past it while under pressure.
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