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Discussion Starter #1 (Edited)
Ok...here's my delimma. I have a the dual resevoir fat corvette style master cylinder with a disc/drum porportioning valve. I ordered a pre-bent 66 L-79 front to rear brake line. The problem is the line goes from the front to the rear on the passenger side. This is not correct for a dual master cyl car (such as the 67). The 67 ( I was told) goes up the driver side through the steering knuckle direct to the master cyl/proportioning valve. A single resevoir master cyl line would come up and meet on the passenger side front brake line. Is this correct?

Questions:

1) should I just splice in the L79 brake lines as it comes up the passenger side and run it across the front frame brace over to the driver side where the master cyl/prop valve is?
2 should I just order a pre-bent 67 brake line and hope it comes close to my aftermarket proportioning valve?
3) should I just make a front to rear brake line from scratch?


Here is my master cyl and proportioning valve:



Is this where my front brakes connect?



Is this where my rear brakes connect?



What is this plastic peice? A bleeder? How do I properly bleed this dual cyl master cyl through the proptioning valve?


What's the brass fitting on the rear section of the proportioning valve? Is this the adjustment for the front to rear valve?



Sorry for all the dumb questions. :D

Dave
 

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Hi Dave,

I don't know for sure, but a pre-bent line for a 67 may come close to what you need. You will likely have to re-bend it a little to fit your proportioning valve. And the flare nut on the end of the 67 line probably won't screw directly into the proportioning valve. You will likely need to use an inverted flare adapter (available at most auto parts stores).

If you decide to make your own line, you can buy a roll of steel brake line at many auto parts stores. You will also need to buy the appropriate size flare nuts and may still need to use an adapter to fit the rear brake line outlet of the proportioning valve. The rear outlet takes a flare nut that has larger threads than what is normally used on 1/4" line. You will also need a good double flaring tool.

Another option is to purchase pre-flared lengths of steel brake line. The max length available is either 60" or 72" so you will have to join two sections together with a coupler. Again, you'll probably need an adapter to fit the proportioning valve since the pre-flared brake lines have "standard" sized flare nuts on them.

The two small ports (your photos #2 and #3) are where the front brake lines connect. The proportioning valve has a built-in Tee so there are two front outlets. It doesn't matter which one you use as far as left/right goes. You could even install an inverted flare plug in one and run a single line to a separate Tee fitting for the front brakes.

The plastic piece (your photo #4) is the connector for the pressure differential switch. This can be used to add a "BRAKE" warning light to your dash that will come on if you loose pressure in either the front or rear brake system. Run a wire from this connector to one side of the bulb. Run a wire from the other side of the bulb to a +12V source that is switched via the ignition switch.

As for bleeding the dual MC through the proportioning valve, you shouldn't have to do anything special. Just bench bleed the master cylinder, hook it to the proportioning valve, and finish bleeding the system through the bleeder screws at the calipers & wheel cylinders.

The brass fitting at the rear of the proportioning valve (your photo #5) is where you connect the rear brake line. It appears as though your proportioning valve may have already come with the adapter fitting that I mentioned earlier. If that is the case, the standard size inverted flare nut on a 1/4" brake line should screw right into that adapter.

The "proportioning" valve you have is basically a copy of the GM combination valve that was used on many 1971-up vehicles with front disc brakes. The original GM ones were cast iron though. These valves contain a metering valve for the front disc brakes. It slightly delays the application of the front brakes to help reduce pad wear and help rear end stability. The porportioning valve section is non-adjustable.
 

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Hey Ray, you sound very knowledgeable about this... i have the same valve on my master. the fitting in the rear of unit was removed by the salesman at time of purchase because i was running 4 whl discs and he said it was only needed for drums... does this sound right to you ???

i hope this in a way helps you too Dave... yer runnin' discs too aren't you ???


don't mean ta take off subject if yer runnin' drums. ;)
 

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Hi Flyer,

If you look closely at Dave's last photo, you can see what looks like a large nut/fitting on the back end of the combo valve and another adapter screwed into that.

The adapter simply changes the size of the threads so a regular size brake line nut will fit.

The larger nut/fitting that screws into the combo valve holds the proportioning valve in place. I'm not all that familiar with the internals of these aftermarket style combo valves, but it may be possible to simply remove (and leave out) the proportioning valve section for use with 4-wheel disc. Of course, that large nut/fitting would need to be put back in place so you have a place to attach the rear brake line.
 

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OK thanks... the fitting on mine had the same size in, as out, so the brake line fitting will fit directly into valve... he just removed that fitting.


i was considering an adjustable valve and do away with the supplied one... but thought i'd ask about it...

Thanks again :)
 

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Discussion Starter #6
Ray...you have been a huge help. Thanks for spending the time to respond. Ok...let me make sure I have this straight.

The front has seperate lines going to each side? These go to the front side of the proportioning valve in the two seperate outlets? Do I need to plug of my T-blocks where the lines are no longer coming out to feed the passenger front and the rear?


The rear brakes have one line feeding both rear drums. This comes in through the back side of the proportioning valve. is this correct?

Couldn't I just splice in the passenger side where the rear line comes up and run it across where the factory front brake line is run across the frame support to the rear side of the proportioning valve? I'd hate to not use the pre-bent L-79 brake line I already bought but I am up for suggestions.:D

Dave
 

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Hi Dave,

You're welcome.

You have a choice as to how you plumb the front brake lines. You could either:

(A) Make use of the proportioning valve's built in Tee. For this, you would run a line from one of the prop valve front outlets to the LH caliper and a separate line from the other prop valve front outlet to the RH caliper. You'd have to bend your own front lines for this configuration.

(B) Make use of the existing front brake lines and Tee block to feed the front brakes. For this, you would plug one of the prop valve front outlets using a special inverted flare plug. Then run a line from the other prop valve front outlet down to the stock driver side Tee block. You may even be able to re-use the line that connected to the old master cylinder for this (otherwise bend your own). You would also need to install an inverted flare plug in the outlet of the passenger side Tee block where the old rear brake line used to connect.


As for the rear, yes, there is one line that comes out of the back of the prop valve and feeds both rear brakes. There's usually a factory Tee fitting built into the end of the rubber flex line that connects to the rear axle.

Your idea of using the new L-79 rear brake line you already have should work. With an appropriate sized inverted flare coupling, you should be able to connect on an "extension" line and run it across to the driver side and connect it to the rear outlet of the prop valve.
 

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Discussion Starter #8 (Edited)
Thanks Ray!

Makes perfect sense. Good news. I have the rear brake lines completed under the hood and it actually looks really clean and nice...I used the new aftermarket front to front brake line as a template when I bent the 1/4" rear tubing to run across frame support. I just added some extra on each side to splice into the components (prop valve and L-79 front to rear brake line).

....However, I have some more questions.:D

Why is there a 1/4" brake line going from the rear resevoir of the master cyl to the rear section of the prop valve only to come out the rear prop valve as a 3/16"?

The front to rear L-79 brake line I bought is a 1/4" line. So the line I created (bent) that splices into the the passenger side L-79 front to rear brake line that runs across the front frame support over to the rear section of the prop valve is also 1/4". However, I had no choice but to run a 3/16" line out the rear prop valve and splice it into the 1/4" line (I created) about 5" below the master cyl.:confused: :confused: I just don't understand why the inverted flare coming out the rear prop valve is only 3/16" when everything else (line between master cyl and prop valve and the entire rest of the rear front to rear brake line) is 1/4"... Seems ascinine to me.

Also....I bought a aftermarket factory front to front brake line for my 66. Now the fittings on the aftermarket front to front line is smaller than the factory. I think (b/c I threw out the old brake line away:eek: ) both (factory and aftermarket) front to front brake lines were 3/16 however the fittings on the end are different sizes. The fittings are too small on the aftermarket front to front brake line to screw into the blocks. :confused: :confused: So it looks like I need to cut the aftermarket lines where the flares are and run a bigger 3/16 fitting with bigger threads and re-flare. :confused: :confused: or should I just try and find an inverted flare and adapt it in? I am having a hard time finding inverted flares with different sizes going in and out of them. Seems they are always 3/16 in and 3/16 out. 1/4 in and 1/4 out..

I am so sick and tired of trying to peicemeal these brakes together. I guess this is the punishment when you try to build the non-factory brakes from scratch. I have made over 6 trips to the hardware stores and autoparts stores trying to find inverted flares, tubes, etc that nobody carries. What a PITA! I get the deer in the headlights look.:eek: :confused: :eek:

Everything else I have under control. I even have the plug for the passenger side block rear exit hole.
Hope I didn't confuse you.:D Ray..you have been a huge help! Thanks again for all the help you have given me thus far.

Dave:)
 

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Hey Funky, check out this link from MP Brakes - http://www.mpbrakes.com/typical.htm. Since you are running a disc/drum setup, you will need to install a residual valve between the mc and the rear brake wheel cylinders - preferrably on the firewall. I think the prop valve you have does not include the residual valves. That is why you have 3/16 threads on all the ports. For a disc/drum set-up you need to run 3/16 line for the front discs (which you did) and 1/4 line for the rear drums. If running 4 wheel disc, then use 3/16 all around. I think since your prop valve has a 3/16 port out the rear that the residual valve will have a 3/16 in and 1/4 out. You can check with MP or other brake vendors on that. If so, that will solve your problem. Also, you may want to make sure your prop/combo valve is for a disc/drum system. BTW, the residual valve keeps pressure in the rear line assuring that the brake shoes do not retract too far from the drums when the brakes are not applied. This will give a firmer pedal when you do apply the brakes.
 

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Discussion Starter #10 (Edited)
Humm...never knew about a residual valve.:eek:

EDIT: I just ordered a residual valve for my set up. Damn...looks like now I am gonna have to revisit all my rear plumping again. Last thing I need is spongy brakes. They were spongy before I tore it apart so no need to revisit this again. Thanks for bringing this to my attention! I HATE BRAKES!!! URGGG!!!!!

Dave :)
 

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Funky, don't feel that you are alone on this issue. I have 4 or 5 different tubing benders and 3 different flaring tool kits, and I've gone through countless lengths of well-intented, pretzeled brake lines. I'd almost bet that somewhere in my (currently frozen) garage I might even have that fitting you were looking for. Just think, after this job, you'll be much better equipted to take on another brake line plumbing job.:D I'll bet you can't wait:D
 

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Discussion Starter #12
Fast65 said:
Funky, don't feel that you are alone on this issue. I have 4 or 5 different tubing benders and 3 different flaring tool kits, and I've gone through countless lengths of well-intented, pretzeled brake lines. I'd almost bet that somewhere in my (currently frozen) garage I might even have that fitting you were looking for. Just think, after this job, you'll be much better equipted to take on another brake line plumbing job.:D I'll bet you can't wait:D
So true. I have like 10 of each different types of fittings Inverted flares, adaptors, tons of the short twisted lines (<---non which work:rolleyes: ). Flare tool that is supposed to be good but only half as$ works..:rolleyes: Tubing bender than can only bend tubing so tight...:rolleyes: and to buy pre-bent brake lines $$$ only to find out I ordered the wrong set or the fittings won't work with my factory blocks just chaps my as$!!!! Then to top it off...eveytime I go to get something to adapt two incompatible lines NOBODY has the brass flare fittings. God forbid I walk in an auto parts store and ask for plain brake lines or inverted flares!!:rolleyes: :rolleyes: :mad:

I walk in and ask..."Where is your bolt drawer in the back?" Thanks....

/Rant off:D
 

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Hey Dave, I can't tell for sure from your firewall pic, but it looks like your Nova may have been a powerbrake car. Is that true? Anyway, my 63 was and now I'm converting to a manual master cyl. Since I can't use the power booster push rod with the new m/c I need to fab one. Do you have or can you take a pic of the manual push rod that you are using? If not, just let me know what the overall lenght of it is - if you can......Thanks...Frank
 

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Discussion Starter #14 (Edited)
Hey Frank,

I can tell you my sedan was a factory single resevoir non-power brakes system.
'
Here you go....to a brutha from anotha mutha! I will measure the rods length when I pull the master cyl back out to paint it with a cast color. Otherwise it will probably be rusted in just a matter of time.



JUST AN FYI TO EVERYONE EVER CONVERTING TO DUAL MASTER CYL:
#1 The front to front brake line on a single master cyl set up is 1/4". This is because the front brake line has to feed the entire brake system (rear too). It's one continuous 1/4" line.
#2 This also means on a factory single resevoir set up.. the front T-Blocks and metal lines that feed the front brakes are fitted for a 1/4" brake line going into the T-Block.
#3 The front to front brake line on a dual master cyl set up is 3/16". This is because the front brake line only feeds the front brakes and the rear brakes are feed by an entirely different different brake line that is 1/4".
#4 This also means on a factory dual resevoir set up... the front T-Blocks and metal lines that feed the front brakes are fitted for a 3/16" brake going into the T-Block.

LAST BUT NOT LEAST. The front to back brake line for a single resevoir runs up the passenger side and the for a dual resevoir runs up the drivers side.

MAKE SURE YOU ASK BEFORE YOU ORDER ANYTHING IF YOU DON'T KNOW! I'D BE HAPPY TO SHARE MY EXPERIENCES WITH YOU AND WALK YOU THOUGH WHAT TO DO.

If I had only known then what I know now I would have ordered everything correctly in the first place......:rolleyes: :rolleyes:

Live and learn,:eek:
Dave:)
 

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Discussion Starter #16
Fast65 said:
Dave, thanks for the pics and the list of info on the m/c conversion. Rest assured that will help many of us here. If and when you pull the m/c that push rod length dimension will really help me out.....Frank
No problem. I will definately get this measurement for you. I will pull the master cyl once I get the brake lines completed and mocked up. (2-3 days?)
 

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Discussion Starter #17
So...I get me residual valve in today. Look at the box it's in and it appears they put the residual valve in backwards. No big deal...but don't show the flow going in the wrong directions on the box if your employees can't stick the valve in the box in the right direction.


One other question:
What in the world does it mean by: "Locate valve lower than wheel cylinders or calipers"??????!?!?!?

It tells me to "insert valve in line close to master cyl" ...OK....whats the point of telling me to locate valve lower than wheel cylinders or calipers.

Since I paid $26 for this measly part, It would be nice to be a little more clear on the instructions not to mention stick the part in the package so the flow diagram matches the box.


 

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Funky,
Where did you get your mastercyl, and pro port. valve from? I
got the kit from CPP, and mine has the residual valve built in,
makes it easier to hook up.
I used 67 brake line kit, manual disc, with drum rear. The original
push rod worked fine for me, no mods. I had to use a different
bushing to hook up the rear brakes at the back of master cyl.
I mounted a line lock on the ppv that's why the bracket isn't on
the master cyl, I'll add it this winter. Brakes work great.
Good luck, Rich
 

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Discussion Starter #19
66RICH said:
Funky,
Where did you get your mastercyl, and pro port. valve from? I
got the kit from CPP, and mine has the residual valve built in,
makes it easier to hook up.
I used 67 brake line kit, manual disc, with drum rear. The original
push rod worked fine for me, no mods. I had to use a different
bushing to hook up the rear brakes at the back of master cyl.
I mounted a line lock on the ppv that's why the bracket isn't on
the master cyl, I'll add it this winter. Brakes work great.
Good luck, Rich
Honestly, I can't remember. I bought it from a large vendor at the Carolina Auto Fest at Lowes Motor Speedway during the fall. I'll check the receipt when I get home. I believe it was CPP but not sure. I will then go online to see if the proportioning valve that I have has a built in Residual Valve. If so, I don't need to install the one I have otherwise I could have big problems. This would mean I have too much residual pressure and my brakes would probably not release once the pedal is depressed.

Do you have 4-wheel disc brakes or front wheel disc brakes?> ..curious.

Thanks a ton for bringing this to my attention Rich.

Regards,
Dave
 
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