Help me find a proportioning valve

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Joined
Mar 14, 2014
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Texas
My Car
1971 Mustang Convertible 351c 4v 4 speed

2013 Mustang Boss 302
I posted a few days ago about my brake issue and the general consensus is that the proportioning valve needs to be replaced. I nor my mechanic can seem to find a factory style one for my car. Anyone have any sources? 71 Mach 1 429 SCJ.

Joel

 
Thats not a proportioning valve it's a distribution block..That means 50-50 brake bias..Be careful thats what the prior owner installed in my green 72 when he did the front disc conversion..The brakes were extremely DANGEROUS I knew they weren't right from the get go..I would triple check & make sure it's a COMBO VALVE / PROPORTIONING VALVE If it's D-Block like it says it is, that's not what you want..I ended up with this http://shop.broncograveyard.com/Proportioning-Valve-for-Disc_Drum-Brakes/productinfo/12564/

Works perfect !

 
Tx, I recently took mine apart for inspection and cleaning.

There's really nothing earth moving inside, just a piston and a couple of O-rings.

Mine looks fine with no pitting, corrosion, etc.

I found no reason that it should not be serviceable on my car.

Try it... you may find an obvious, easy fix. Can't hurt at this point.

 
Thats not a proportioning valve it's a distribution block..That means 50-50 brake bias..Be careful thats what the prior owner installed in my green 72 when he did the front disc conversion..The brakes were extremely DANGEROUS I knew they weren't right from the get go..I would triple check & make sure it's a COMBO VALVE / PROPORTIONING VALVE If it's D-Block like it says it is, that's not what you want..I ended up with this http://shop.broncograveyard.com/Proportioning-Valve-for-Disc_Drum-Brakes/productinfo/12564/

Works perfect !
Aren't those distribution blocks set up for the type of brakes that you are using? The one I ordered was Disk/Disk since I converted to rear disks. My original one was Disk/Drum. Seems like a distribution block and proportioning block are the same thing. Didn't realize there was a difference so I am asking just to educate myself. I just thought that you just had to specify what brakes you had.

thx

 
Starting in 1970 the distribution block, pressure differential switch, and the proportioning valve were integrated into one packaged part. What is being sold in the after market I don't know. Additionally, the factory residual pressure valve for the rear drum brakes is located under the brass flare nut seal at the output of the master cylinder. Chuck

 
Starting in 1970 the distribution block, pressure differential switch, and the proportioning valve were integrated into one packaged part. What is being sold in the after market I don't know. Additionally, the factory residual pressure valve for the rear drum brakes is located under the brass flare nut seal at the output of the master cylinder. Chuck
Thx Chuck. When I got my new one I had to specify what brake set up I had. Just wanted to make sure that I didn't have to replace mine again.

-john

 
this part looks correct.

http://laurelmountainmustang.com/products/1968-1973-mustang-brake-distribution-block-2

it has the nut on the bottom that packs the prop valve.

the power disc and manual brake distribution block is different.

the prop and distribution block is all integrated the laurel hill photo shows the pressure warning sensor which shows if you have a leak on one side the system.

inside the block is the prop valve, which is adjustable and can get you into trouble. there is a heavy spring and various seals that bias the brake fluid to lock up the front before the rear drums. basically the valve only effects the rear drums, the front disc brakes bypass the prop valve and full pressure goes to the front disc. the rear is restricted and opens later which keeps the rears from locking up first.

there are rebuild kits that did not exist 5 years ago. internally there isn't much to the prop valve, if the body of the prop valve is in good shape you can rebuild the original. i rebuilt mine with parts from another valve as rebuild kits did not exist back then.

this is a rebuild kit

http://www.mustangsunlimited.com/itemdy00.asp?T1=1G3+01

90% of the time the original rubber seals fall apart or they swell and the prop valve jams and no fluid reaches the rear drums.

you pop the bottom nut on the block to open the prop valve, remove the sensor switch first. then pop the nut, and go slow the heavy spring inside will make the assembly want to fly out so be prepared then carefully remove the assembly and note order of assembly.

now when you go to change the seals you will need to unscrew the bottom from the top, you need to count how many turns you made to take the valve apart because you need to match it during reassembly so that the original OEM pressure is maintained to the rear drums.

you can mess with it and make the drums lock early or later just by turning the screw. this is all from memory about 10 years ago.

my issue was seals were contaminated and swelled locking the prop valve and not allowing fluid to the rear line.

 
the prop and distribution block is all integrated the laurel hill photo shows the pressure warning sensor which shows if you have a leak on one side the system.
Heres a pic of the one that came out of my car was sold by mustangs unlimited..as a D-BLOCK.. it too has the warning sensor but IS NOT a combo proportioning valve..it is a d-block with 50-50 bias not 70-30..So the point is make sure..THAT THE PART YOU GET IS CORRECT..A D-BLOCK splits what comes in 50-50 a proportioning valve splits what comes in unequal..A combo valve is a combination of the 2..There is a huge difference in the 2 parts

IMG_0598.JPG

 
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