Distribution block or proportioning valve?

[67 GTA]

I am trying to finish up my brake system on my 67 fastback. The last area was the lines around the master cylinder and what I thought to be the distibution block. I read an article that said all disc brake cars had a proportioning valve. I have never seen a Prop.valve on my car, only the Dist.block, which has a plunger inside of it. When I looked the Prop.valve up in several parts books they show a picture of what I thought was my Dist.block. Confused yet? So, is it a p.valve or a d.block or both? My head hurts. If it is not a p.valve then how have my brake not been locking up? If it is a p.valve then why is there not a place to adjust the pressure? Someone please help straighten this out for me before I start arguing with myself.

 

[Platonic Solid]

Yes.











Recent experience with this item tells me it is both. It is a Distribution-block in that it distributes the brake fluid. It also has a built-in non-adjustable proportioning-valve that regulates the brake fluid distribution.

 

[WarrenC]

Not trying to confuse things further, but my 67 w/factory discs had the proportioning valve near the rear axle. I was under the impression that the block near the master cylinder was a distribution block only.

 

[67coupe351w]

Yes, I'd liek to know this as well...

I converted to power disc from manual drum but used the same d.block as before. Ive seen it called both as well.

It sure doesn't seem to stop as good as I would expect.

 

[Platonic Solid]

Apparently it varies. It looks like some just have a “Distribution Block” without an integral “Proportioning Valve” (AKA: “Metering Valve” per Chilton). The Chilton book (rather vaguely) states:

“On some vehicles equipped with front disk brakes, a metering valve is used. This valve is installed in the hydraulic line to the front brakes, and functions to delay pressure buildup to the front brakes on application. …”

My 71-73s all have combination units.

NPD sells combination (Proportioning Valve / Distribution Block), non-original, replacement units.

Mustangs Unlimited sells the original (Distribution Block only) replacement units, but I don’t know why anyone with front discs would want to use it.

The only single unit “Proportioning Valves” I see available are the aftermarket adjustable kind.

 

[concreteman]

well I know I'm confused. I just ordered a kit made by stainless steels disk brakes for the front of my 69 that has drums from CJ ponyparts. I asked about a proportioning valve and they said the master that they sell functions as one. Later I checked out stainless steels web site and the same kit shows a proportioning valve in it. Guess I will have to wait till i see it to see if one comes with the one sold by CJ or if I have to buy one seperately.

 

[67 GTA]

Thanks for the info. I'm going to assume it is both since it worked before. The piston inside the block is frozen up, so only my front discs were stopping me when the power booster went out. I will cross my fingers and order what they said I needed.

 

[pabear89]

Both.

When these cars were made with drum systems it is a Distribution block,
with a built in check valve to isolate the front and rear systems in case of failure to one side.

Then the optional Disc front came into play,
They added a external inline porportioning valve on to the dist block.

PB

 

[jbuening]

I agree with PB. I am not a pre-69 guru, but the 69s had what appears as a distribution block but with two extra ports. Those two extra ports had a cylindrical looking proportioning valve attached (basically a brake line from one port then the prop valve and then the other end of the brake line into the second port). Similar to:
http://cgi.ebay.com/ebaymotors/Torino-Fairlane-Mustang-Disc-Brake-Proportioning-Valve_W0QQcmdZViewItemQQcategoryZ34199QQitemZ4568853168QQrdZ1QQsspagenameZWDVW but not the exact one. Notice it has 6 ports, whereas the distribution blocks have four.
After 69, they went with the combination units like
http://cgi.ebay.com/ebaymotors/Mustang-Cougar-Torino-Disc-Brake-Proportioning-Valve_W0QQcmdZViewItemQQcategoryZ34199QQitemZ4568058558QQrdZ1QQsspagenameZWDVW .

Using a distribution block on disc brake car will not allow the proper hydraulic pressures to the front and rear of the car. Ever notice how a drum/drum master cylinder has the same size bowls, but a disc drum has different size bowls?So in summary, for disc/drum you need a disc/drum proportioning valve, for drum/drum you need a distribution block, and for disc/disc you need a proportioning valve from a disc/disc car. Hope this clarifies things a bit

 

[67FBSCODE]

67's

only 67 with discs had a distribution block near the master cylinder and a proportioning valve mounted near the rear axle. All others have a combination distribution/proportioning valve near the master cylinder. I happen to have both of mine off at the moment. The distribution block has a small piston or valve to actuate the light if either the front or rear fails.

 

[67coupe351w]

only 67 with discs had a distribution block near the master cylinder and a proportioning valve mounted near the rear axle. All others have a combination distribution/proportioning valve near the master cylinder. I happen to have both of mine off at the moment. The distribution block has a small piston or valve to actuate the light if either the front or rear fails.

So my 67 that was originally equiped with 4 wheel drum has a proportioning valve built into the dist block?

It sounds like its more of a saftey feature than a proportioning valve though correct?

If not this could be why my power discs arent working like they think I should, I had previously thought low vaccum was to blame (15.5" or so i think it is)

 

[pabear89]

Right, the drum system has a flow check valve for front or rear brake system failures. if the rear dropped a wheel cyl, the pin closes off the rear brakes and allows only the front to work.

PB