What did YOU do for a rear residual valve???

[ldgn63]

I'm having a hard time finding a master cyl for the disk/drum conversion on my '67. (none have internal residual valves for the rear drums)
So I am interested in what YOU (yes you) did for a rear residual... Even if you tell me that you do NOT have one.

Here are the options that I "think" I have:
1. Keep hunting for a master with internal RV
2. steal one RV out of my '67 master (can you buy the internal ones new?)
3. Add an external RV inline.

Would prefer a variance of option 1 (the sooner the better)

Thanks!
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[Scottshotrods]

You can use a Wilwood residual pressure valves 2lb in the front and a 10lb in the rear.
We have them in stock and they are 21.00 each.If you are intrested you can p/m
if you want.
Justin

[lil hoodlum]

I might be wrong but I believe there are two different master cylinders. One type is for the 1967- 1970, all four drums. And the other is for the 1971 and 1972 disk/ drum.

I have after market disk brakes on the front. I am still using the 1967- 1970 master cylinder. However, I did change to the disc brake proporting valve ( 1971, 1972.)

I hope this helps.

Keith

[72MARIO]

Does a 72 master not have residule vallve built in ? Or are they part of the original porp valve /

[ldgn63]

Originally Posted by lil hoodlum

I might be wrong but I believe there are two different master cylinders. One type is for the 1967- 1970, all four drums. And the other is for the 1971 and 1972 disk/ drum.

I have after market disk brakes on the front. I am still using the 1967- 1970 master cylinder. However, I did change to the disc brake proporting valve ( 1971, 1972.)

I hope this helps.

Keith

Keith, my stock 67 master has RV's in front and rear... If u are using that master won't the front be too much pressure on your fronts and wear out your pads or worse get them hot and lock them up?

From what I've read, if the master is on the firewall I only need a 10lb on the rear and nothing on the front. If my reading comprehension is right...
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[ldgn63]

Originally Posted by 72MARIO

Does a 72 master not have residule vallve built in ? Or are they part of the original porp valve /

I asked on another thread and was told that the 72 SHOULD have an internal valve in the rear.... But the parts-store versions do not have them.

I don't think any prop valves have residuals too.
Combo valves have prop for rear and metering in rear.

Anybody else have info on your setup?
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[lolife99]

I thought residual valves were only needed if your M/C was mounted lower than the calipers.
Like on a frame mounted street rod style Master cylinder.

Performance Online sells M/C and boosters or anyother parts you would need.
http://www.performanceonline.com/196...STER-KIT-ZINC/

So do many other companies.

[Shane]

pretty sure you don't need a residual valve if the master cylinder is mounted in stock location ... use a 71-72 master cylinder with a 71-72 prop valve.

[7T2]

I have an unusual but related question. I put a master cylinder conversion kit on my 57 GMC, which now has discs in front and drums in the rear. I have been plagued with a spongy pedal, and (by my own fault) I didn't read the instructions close enough, thinking the system was ready to go for a disc/drum setup. Turns out for sure I need the 2lb residual valve for the front, because the master cyl is lower than the front brakes (under the cab), but I'm not sure about the rear? The instructions aren't printed very clear, and I can't remember where I got it from since it was a while ago. It appears the unit has a combo valve, which would include the 10lb residual valve for the rear.

My question is this: Will it hurt anything to put an aftermarket 10lb residual valve inline going to the rear (so I would potentially have TWO inline)? It would seem to me that it wouldn't hurt anything, and that the residual pressure would still be 10 lbs (or whatever the greatest pressure is on any of the inline valves). Is this true?

[ldgn63]

Originally Posted by 7T2

I have an unusual but related question. I put a master cylinder conversion kit on my 57 GMC, which now has discs in front and drums in the rear. I have been plagued with a spongy pedal, and (by my own fault) I didn't read the instructions close enough, thinking the system was ready to go for a disc/drum setup. Turns out for sure I need the 2lb residual valve for the front, because the master cyl is lower than the front brakes (under the cab), but I'm not sure about the rear? The instructions aren't printed very clear, and I can't remember where I got it from since it was a while ago. It appears the unit has a combo valve, which would include the 10lb residual valve for the rear.

My question is this: Will it hurt anything to put an aftermarket 10lb residual valve inline going to the rear (so I would potentially have TWO inline)? It would seem to me that it wouldn't hurt anything, and that the residual pressure would still be 10 lbs (or whatever the greatest pressure is on any of the inline valves). Is this true?

i have read that 2 residuals inline is a no-no.
Are you 100% positive that the combo indeed has a residual? ive see cutaways of combos and they only point out METERING for front and PROPORTIONING for rear... no residual.

[ldgn63]

It is my understanding that a residual is needed for the DRUM circuit regardless of mounting location to give some pre-load to the drum return springs.
http://www.mpbrakes.com/uploads/docu...dualvalves.pdf
To me that is supported by the fact that my drum/drum master has residual valves in both ports.

Maybe the residual is in the combination valve on the 72…. I guess I’ll find out the long way.
I’ll put it all together and if it has lots of pedal travel I’ll add and inline valve. (if I cant buy one to put INSIDE the master)

FWIW I HATE brake work but I am making an honest effort to learn it and know it well enough that I don’t hate it but enjoy getting it right and knowing exactly how it works and why.
I’ve read many write-ups… but they all spin a little different.

More info on residuals (near bottom) for those inquiring minds: (ford master cyl so pay no attention to it being backwards)
http://www.chtopping.com/str395/str395.html

[7T2]

Originally Posted by ldgn63

i have read that 2 residuals inline is a no-no.
Are you 100% positive that the combo indeed has a residual? ive see cutaways of combos and they only point out METERING for front and PROPORTIONING for rear... no residual.

I know that I definitely need one going to the rear drums, just don't know if I have one. Instructions say the combo valve combines metering, proportioning and 10 pound residual to the rear, so I should be good to go, but to me it's just a big brass block. I don't even see a way to open it up, much less figure out what it is doing inside.

[jablack]

On my 67 I used everything from a mid 80's chevy truck. I even ran the lines and mounted the prop valve the same way. After I bled the lines it works great.

[ldgn63]

Originally Posted by jablack

On my 67 I used everything from a mid 80's chevy truck. I even ran the lines and mounted the prop valve the same way. After I bled the lines it works great.

Thanks. did you use the 80's rear end too? I ask because itwill have a newer slave cylinder cup style that may not require a residual)

[ldgn63]

Originally Posted by 7T2

I know that I definitely need one going to the rear drums, just don't know if I have one. Instructions say the combo valve combines metering, proportioning and 10 pound residual to the rear, so I should be good to go, but to me it's just a big brass block. I don't even see a way to open it up, much less figure out what it is doing inside.

well if the instructions are right it "sounds" like you should be good...
i totally understand the big brass block comment!

parts store folks have just scratched their heads when i mention residuals...

[ldgn63]

The most comprehensive article (2 parts) that I have found on brake valving:


http://www.thebrakeman.com/valvetechi

http://www.thebrakeman.com/valvetechii



history on me…
I’ve only done one other disc conversion and it was on a ’63 Impala (affectionately known as the PIMPala) and I have always hated the result. I went with a “complete kit” from XXXXXX’s. It came with master and an adjustable prop valve. Installed everything per directions and bled the system EVERY way known to man but that car has massive pedal travel and a little nosedive to this day. After mass searching and reading I am now sure it really needs a combo valve (metering front/prop rear) and a 10lb residual in the rear to give me the pedal feel I want. The car stops ok now but the brake is almost at the floor and I hate that. I honestly think the original power drums worked better. Anyway, I want to get this truck SOLID and use what I have learned recently to fix the PIMP.
Fortunately, the truck has the perfect spot to add an inline residual if I put it all together and decide that it needs one. I would just put one inline up front but have read that you don’t want 2 in one circuit… … I would rather not have to break apart the lines after bleeding since one-man bleeding is enough of a pain on the first go around! Which is why I am asking you folks what YOU have on your truck. ;-)

[jablack]

I used a rear out of a 71. I rebuilt the brakes, but just used stock 71 parts.

[Tx Firefighter]

You guys are way overthinking this. Follow the factory engineer's lead and use the OEM parts off a later truck.

Use a a factory master cylinder and proportioning valve off a truck that had factory front disc brakes. You can choose any master cylinder from the 70's or even the aluminum with plastic reservoir off an 80s vintage truck.

I've done this a lot of times. It works. Jablack's way works very well too, just take every line, valve and hose off a later truck. I've done that too.

You use those inline valves when your master cylinder is mounted down low like street rods or very old cars. The master cylinder was actually lower than the brakes on cars and trucks built up into the 50's. Without the valves, gravity would cause the fluid to run from the brakes back to the master cylinder and cause it to overflow.

[ldgn63]

Thanks TX
In reality I started that way only to find my donor was crap.
As it stands now the residual or lack thereof is my hold up.

Anybody that didn't use a donor truck got input on what they did?
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[Shane]

you're going in circles ... again, you don't need a residual ...

[lolife99]

Aftermarket proportioning valve from Performance OnLine.
Nothing else.

[ldgn63]

Originally Posted by Shane

you're going in circles ... again, you don't need a residual ...

Circles... That would explain why I never get anywhere! Lol
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[MT1972cheyenne]

I had a 56 Chevy pickup that had a 74 Nova front clip (discs) & a 69 Caprice (drum) rearend. I went to the junkyard and got a master cylinder from a 74 nova (front discs) that didn't have power brakes, mounted it under the cab, and it worked fine. It was close to a stock ride height, so I would say the master cylinder was above the calipers.