need advice on proportioning valves

[road warr1or]

Im doing a disc brake swap on a 69 fastback. Can someone clarify the proportioning valve issue with mustangs. I have a standard distribution valve in the car now. I researched the proportioning valve for a 69 and they appear to be not really available. So I guess Im going to use a valve from a 70 stang or comparable auto.

when I researched the prop valve for a 70 stang, and a granade valve they were much smaller than the 69 and were missing a small cylinder object piped into two fo the ports on the prop valve found on the 69. What does this cylinder do? and why is it not found on later models. When i compared the granada and 70 stang valves they were very similar are thes ok to use?

A second qustion:

How much different is the brake pedal for a standard braking system from an auto system and is there any way to modify it without getting a new pedal

Thanks for the help

Im so confused!

 

[Rusty67]

First off, are you doing front and rear or just fronts ?

The factory distrobution block doesn't do anything other then shut off a circuit when it looses pressure (if only 1 looses pressure) and split the direction of the fluid. It also might activate the brake warning light in the dash depending on which one you use. I don't have one in my setup anymore because it failed on my and I don't want to get into that story but let me just say that I'm now of the opinion that they should be removed before they fail.

The cylinder you are talking about is a residual pressure valve which is needed in drum circuits in order for the drum brakes to function properly. These are not used on all models because some master cylinders have them built into the ports. Also, cars with disc brakes need to NOT have them plumbed into the circuit.

You don't NEED a proportioning valve unless your brakes don't function properly. I don't have one in my setup and my car brakes like a champ. You can use one to dial in the way your brakes respond but they are not always neccesary.

 

[75 mustang II]

proportioning valves

I converted my 69 to front disc.Bought the adjustabl prop valve from CJ pony.Got the brakes all bled and everything is working well.75 mustang II

 

[pazur]

Manual proportioning valve is the safest bet. Sumit sells one for $35+$11 handling. If you have standard 3/16" brake lines, line fitting will be needed. Fixed proportioning valve taken from other car is nearly 100% likely that your brakes will be inefficient. You end up braking too much or too little with rear brakes, which will cause premature wear of brake pads on either end, and longer stopping distance.

 

[gsxrken]

SSBC now makes a distribution block that has a built in prop valve. for about $100. You can go that route, or just tee in a generic prop valve from Wilwood or Summit on your rear line circuit that allows you to reduce pressure to the rears until your fronts lock up before you rears in a panic stop.

 

[D.Hearne]

When I did the swap from 4 drums to 4 discs in my 67, I just left the Proportioning valve as is. Worked fine. (manual discs)

 

[gsxrken]

When I did the swap from 4 drums to 4 discs in my 67, I just left the Proportioning valve as is. Worked fine. (manual discs)

4 wheel drum cars don't have proportioning valves. The balance is achieved by varying the bore diameter of the wheel cylinders and the leverage aspects of differently sized drums.

 

[road warr1or]

So when I mount the proportioning valve into the braking system., do I place it between the master cylinder and distribution block or after the distribution block on the brake line for the rear brake

 

[D.Hearne]

4 wheel drum cars don't have proportioning valves. The balance is achieved by varying the bore diameter of the wheel cylinders and the leverage aspects of differently sized drums.

Then what was that metal block bolted to the fenderwell that all the lines went into-out of ? And why did my brakes work fine after the swap, that also included a different master cylinder ?

 

[5.0ina66]

Then what was that metal block bolted to the fenderwell that all the lines went into-out of ? And why did my brakes work fine after the swap, that also included a different master cylinder ?

That's just a fluid distribution manifold, distribution block in 'brake speak'. No valves or anything inside it.

 

[gsxrken]

Then what was that metal block bolted to the fenderwell that all the lines went into-out of ? And why did my brakes work fine after the swap, that also included a different master cylinder ?

D., you are probably describing the distribution block, which is a brass block with several ports on it for MC in, Rear line out, and usually two front lines out. It was just a means to route fluid. Some distribution blocks also have a little shuttle valve in them to trip the brake warning light on the dash when there is leak on one of the axles.
I just googled and landed on this site, which also makes the point: http://www.stangerssite.com/brakevalve.html
"This section deals with the Proportioning Valve used primarily on the 1965 & 1966 Ford Mustangs with Front Disc Brakes. It mounted on the drivers side rear fender apron, between the shock tower and the firewall, under the hood hinge. This is not to be confused with the Distribution Block, a brass piece that distributes the fluid coming from the master cylinder.
A Proportioning Valve is only found on cars with disc brakes. It is spliced in the brake line running from the master cylinder to the rear wheels. Its purpose is to dampen and reduce brake pressure going to the rear brakes."

On my disc brake 69, you can see the proportioning valve separate from the distribution block in this pic: http://www.geocities.com/gsxrken/Mustang/Mustang2/100_2259.jpg

EDIT: as for why your car works well without one, you may just be lucky! Most OEMs built in bias with caliper bore sizes where the rear brakes only have about 50% of total piston bore diameter as compared to the front calipers. So right there, even without a prop valve, you have half the force at the rear. Depending on your front and rear caliper selection, you may have landed on a decent combination. Have you ever tracked your car, or even better to show it, tracked your car in the wet? At extreme braking, like on the end of a straight into the infield, you may find your tail-end moving around back there before the front locks up. Not good. On the street, you might never notice it. Hey if it works for you, leave it alone.

 

[Rusty67]

gsxrken, that is not a proportioning valve in that picture. It is a residual pressure valve. It keeps 10psi in the brake lines at all times for the drum brakes.

I don't have a proportioning valve on my system, just a 10psi residual pressure vavle for the rears and my brakes work like a champ. The only problem with my setup is the lack of a power booster makes for a hard pedal with that SVO MC.

 

[gsxrken]

gsxrken, that is not a proportioning valve in that picture. It is a residual pressure valve. It keeps 10psi in the brake lines at all times for the drum brakes.

Rusty, it is the proportioning valve. The residual valves are usually in the port on the MC body, although I have heard some earlier cars had them in line.

I'll post a scan of my shop manual when I get chance.

 

[gsxrken]

Here we go:
http://www.geocities.com/gsxrken/Mustang/brake_prop_scan.jpg

 

[Rusty67]

Well, looks like I'm wrong but I'm not ashamed to admit it. In my defense I do have to say that it looks exactly like a residual pressure valve

 

[road warr1or]

wow I wasnt expecting this much great infromation thankyou very much.

Gsxrken
so that proportion valve is mounted o a 69? Im just curious it is so much different from many of the other valves Ive searched for on ebay. it seems like the only year with a valve like that. I saw a 70 mustang valve with disc brakes and it was smaller and minus that built in proportioning valve. In addition, the granada proportioning valve used in the granada swap looked almost identical to the 70 mustang valve. and some of other year autos with swap cababilities were were also similar.

 

[Grabber70Mach]

wow I wasnt expecting this much great infromation thankyou very much.

Gsxrken
so that proportion valve is mounted o a 69? Im just curious it is so much different from many of the other valves Ive searched for on ebay. it seems like the only year with a valve like that. I saw a 70 mustang valve with disc brakes and it was smaller and minus that built in proportioning valve. In addition, the granada proportioning valve used in the granada swap looked almost identical to the 70 mustang valve. and some of other year autos with swap cababilities were were also similar.

They changed the valves between 69 & 70, if I remember correctly a 69 mounts horizontally and a 70 mounts vertically and doesn't have the separate cylindrical proportioning part, it is internally built in. With that being said you have to adapt or replace the two front lines and the line running to the rear. If you do this the rear rubber line is also different and so is the bracket that mounts to the floor pan where they join, well its the same bracket just in a slightly different location.

 

[D.Hearne]

The setup I used on my 67 was 71-73 Mustang front discs and Versailles rear (off a Monarch actaully) Master cylinder was for a 71 Ford Custom (full size car, decendant of the Galaxie) for Manual disc brakes. I no longer have the Stang, it got sold in 89. The one thing I do recall about it's braking was you couldn't lock em up, no matter how hard you stood on em. It had no problem hauling it down from 140 mph to a dead stop.