Proportioning valve?

stolan83 · Post subject: Proportioning valve? (Mon Mar 26, 2012 10:58 pm)

Did a kh swap and am using a split master cylinder, bigger res. up front , normal behind that. Do I still need a proportion valve, my thought in no?

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225+0.080 at 10:1
268cam
holley 390
clifford headers
8 3/4 355's lsd
kh brakes
electronic ing

Joshua Skinner · Post subject: (Mon Mar 26, 2012 11:01 pm)

You do want a proportioning valve, yes.

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Joshua Skinner
car nut, telecom tech, tool using mammal
'72 Dart Swinger

stolan83 · Post subject: (Mon Mar 26, 2012 11:15 pm)

Ok thank you, is there one that is recommended or will the cheap summit brand work? Also what is the correct proportion 70 30 front to back?

_________________
225+0.080 at 10:1
268cam
holley 390
clifford headers
8 3/4 355's lsd
kh brakes
electronic ing

CNC-Dude · Post subject: (Mon Mar 26, 2012 11:28 pm)

Wilwood makes a good one. I don't know that I would shop for "cheap" when hunting brake related items Shocked

.

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There's no such thing as too much cam....only not enough engine!

ValiantBoyWonder · Post subject: (Tue Mar 27, 2012 10:24 am)

here are the different Wilwood valves: http://www.wilwood.com/MasterCylinders/MasterCylinderValves.aspx

if you're running stainless lines you're going to have to mock up fitment. use item# 260-10922

if you're running AN line use item# 260-8419

they are basically the same, only the 8419 comes with adapters from 1/8npt to 3/8. i asked someone about this and they said it's so you can run the AN plumbing.

you can get both these valves from amazon for cheaper (i believe), the wilwood site just gives better specs.

or, if you really want do it right, go here and call these guys, tell them what you got, and they might help you out.

http://inlinetube.com/Prop%20Valves/pro_valves.htm

either way, do your homework on this one. search google and search this site for more info.

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70 Plymouth Valiant 4dr

stolan83 · Post subject: (Sat Mar 31, 2012 12:01 am)

Sorry if this s dumb question. Do i still use the metering block or does the proportioning valve take its place

_________________
225+0.080 at 10:1
268cam
holley 390
clifford headers
8 3/4 355's lsd
kh brakes
electronic ing

ValiantBoyWonder · Post subject: (Sat Mar 31, 2012 9:52 am)

no dumb questions here friend. yes, run the prop. valve between the master cylinder and metering block. click on the link and that thread seems to have some good info.

great picture on this link of a prop valve SKINNER, thank you

http://slantsix.org/forum/viewtopic.php?t=45679&highlight=proportioning+valve

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70 Plymouth Valiant 4dr

sandy in BC · Post subject: (Sat Mar 31, 2012 10:36 am)

If you have the correct combination valve you dont need an aftermarket prop valve.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

http://www.arrowtipi.com/My%20Webs/index%20Valiant.htm

WagonsRcool · Post subject: (Mon Apr 02, 2012 3:12 pm)

First I think you need to understand what all of the parts are & what they do before you can figure out what it is you need for your car. For a 4 wheel drum brake car with a "dual-circuit" (67? - & up) system, the two master cylinder lines went to a distribution block. Usually the block had 3 outlets- 1 for the rear brakes (1 M/C circuit), 1 for each front brake (the othe M/C circuit). Also in the block was a switch that would turn on a warning light if either circuit lost pressure. (IMO, if you needed a light to tell that you just lost most of your brake pedal/ effect, then you really shouldn't be allowed to drive). Drum brakes were designed to be "self balancing", front to rear. So the hyd. pressure going into the block went staight out.

That changed with front disc brakes. They "apply" at a different rate than drums. What happened was the rear drums would lock up while the front discs were barely working hard. So a device was needed to modulate (reduce) pressure to the rear brakes. This is the proportioning (prop)valve. Below its "setpoint" (400 psi for example), pressure to F & R brakes is the same. Above that, pressure to the R is increased at a fixed proportion of the F pressure(say at 1:2 ratio). So at 800psi F you might have 600 R, at 1000psi F you'd have 700 R, etc.

Some early prop valves were "added-on" to the rear brake circuit from the factory. Soon they were intergrated into the distribution block to create the combination (combo) valve. Later units also added a metering valve to the front brake circuit. (this [useless]valve was supposed to "delay" front disc apply until rear drums built up 20 psi or so to overcome return spring pressure- the idea was to have completely even F-R apply when lightly stopping).

So, if you are using parts that recreate one of the factory disc / drum setups, then you should do fine if you can get a matching factory combo valve. Otherwise you can use an adjustable prop valve that is (correctly) plumbed into the rear circuit. Just be sure to NOT drive the car on the street until you dial-in the adjustment that works for you (I aim to have the fronts lock up just before the rears- & I recheck after the new friction has "worn in" some).

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63 Valiant Wagon
225 - 4 bbl

ValiantBoyWonder · Post subject: (Mon Apr 02, 2012 4:27 pm)

Thats some sound advice and information. Wink

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70 Plymouth Valiant 4dr

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