Proportioning valves

[67 twins]

When I upgraded the wife's 67 to disc brakes I got a proportioning valve from a 71 thinking the best thing would be an original GM part made for these trucks. Worked great, but as a risk you always rum with used parts this one is now leaking.
So how do I find a new one that's correct for this truck. It seems when you search online it seems everyone lists a generic (disc/drum proportioning valve). If it were that simple the OE's would use one part number for everything.
Anyone have any good information?

[jimijam00]

Are you sure it is the valve that is leaking?

[67 twins]

Originally Posted by jimijam00

Are you sure it is the valve that is leaking?

Yes

[jocko]

Is it leaking from a port or is the valve cracked? Only asking because originals aren't reproduced, your only option is generic - so if it's just a connection somewhere, certainly worth fixing that - but I'll assume that's not the case and you need a new one. A combo valve is a combo valve, but if you want to feel more comfortable with which one you choose - recommend touch base with member pickmup, he sells some very nice complete assemblies that have an aftermarket combo or valve, he might be able to tell you which aftermarket valve he recommends.

[geunther]

If you can locate from where it is leaking, I might be able to help you. I spent some time sizing and trying different O rings. I was able to rebuild mine and it does not leak. The reason I can help is because I had to buy the O rings in bulk and will happily send you some for the cost of shipping. Actually, Ill just put them in a letter envelope.

I also bought a generic combo valve that fits exactly where the factory one fit with no mods to any of the connecting lines. Ill get you that number as well.

[67 twins]

Originally Posted by geunther

If you can locate from where it is leaking, I might be able to help you. I spent some time sizing and trying different O rings. I was able to rebuild mine and it does not leak. The reason I can help is because I had to buy the O rings in bulk and will happily send you some for the cost of shipping. Actually, Ill just put them in a letter envelope.

I also bought a generic combo valve that fits exactly where the factory one fit with no mods to any of the connecting lines. Ill get you that number as well.

It's leaking out of the front of the valve

[geunther]

Originally Posted by 67 twins

It's leaking out of the front of the valve

Because of this, I would go with a new one. The front is where the metering valve is and I have not been able to locate those components.

Put a small bucket under that part and pull out the metering valve by remove the spring retainer. Perhaps that will all clean up. That will drain the front reservoir, thats why the bucket.

You can remove the brake light switch and with a skinny tool (awl or similar) and move the switch slider towards the front to block the front circuit. It will still drip fluid, but it will be much slower.

[67 twins]

Originally Posted by geunther

Because of this, I would go with a new one. The front is where the metering valve is and I have not been able to locate those components.

Put a small bucket under that part and pull out the metering valve by remove the spring retainer. Perhaps that will all clean up. That will drain the front reservoir, thats why the bucket.

You can remove the brake light switch and with a skinny tool (awl or similar) and move the switch slider towards the front to block the front circuit. It will still drip fluid, but it will be much slower.

Thank you for the information

[dmjlambert]

Originally Posted by geunther

If you can locate from where it is leaking, I might be able to help you. I spent some time sizing and trying different O rings. I was able to rebuild mine and it does not leak. The reason I can help is because I had to buy the O rings in bulk and will happily send you some for the cost of shipping. Actually, Ill just put them in a letter envelope.

I also bought a generic combo valve that fits exactly where the factory one fit with no mods to any of the connecting lines. Ill get you that number as well.

Hi geunther, I wrote you a PM to see if I may also get some or those o-rings from you. I would appreciate it very much.

[dmjlambert]

I would also be interested in the brand name and part number that fits where the factory one fits, because I don't have an old one to rebuild. Thanks.

[geunther]

So there is not a part number listed other than "71-72-C10", but below is the link to the one I bought. I did not install it but I did confirm that it fit exactly as the original and all original brake lines connected.

This might be the same as all the other vendors sell, but I can't speak to that.

Mine also came with two fittings for the brake light switch. One of which will connect directly to factory harness.

https://www.carolinaclassictrucks.co...ake-valve.html

[SRU1436]

Originally Posted by geunther

So there is not a part number listed other than "71-72-C10", but below is the link to the one I bought. I did not install it but I did confirm that it fit exactly as the original and all original brake lines connected.

This might be the same as all the other vendors sell, but I can't speak to that.

Mine also came with two fittings for the brake light switch. One of which will connect directly to factory harness.

https://www.carolinaclassictrucks.co...ake-valve.html

Did you install this? If so does it leak?

[Keith Seymore]

Originally Posted by 67 twins

If it were that simple the OE's would use one part number for everything.

Correct. Each unique part number was tuned for meter/split point/rear wheel pressure slope based on vehicle weight, CG location, wheelbase, front disc (or wheel cylinder diameter), rear wheel cylinder diameter, friction material, etc.

Releasing one size to fit all is like having one carburetor (and tune) to cover all engine applications.

K

[67 twins]

Originally Posted by Keith Seymore

Correct. Each unique part number was tuned for meter/split point/rear wheel pressure slope based on vehicle weight, CG location, wheelbase, front disc (or wheel cylinder diameter), rear wheel cylinder diameter, friction material, etc.

Releasing one size to fit all is like having one carburetor (and tune) to cover all engine applications.

K

So knowing this, what would you recommend?

[May70]

I read once and have a note in sharpie in my folder:

FROM A VERY EXPERIENCED TRUCK GUY: GOOD FUNCTIONING ORIGINAL OR WILWOOD PROP VALVE - NOTHING ELSE!!!

For what its worth, Im going to follow that. AKA im going to buy a wilwood product. Cant remember where I read it or who told me.

[68 P.O.S.]

If you really want to keep the original truck valve, you could send it to Old Auto Restorations, or somewhere else, to have it rebuilt. Or you can try your hand at rebuilding it yourself.

[burnin oil]

A generic PV2 proportioning valve should work fine. It's a GM disc/drum. I ran one for years in a dodge 2500 when I bypassed the failed ABS system and it worked better than factory. I know have one for my 57 waiting for install.

[RichardJ]

Metering valve.

[Accelo]

New Proportioning valve arrived. China but I suspected that.
What's funny part is the quality control sheet that arrived with the valve.
I'm hopeful this one doesn't leak, in two places!

[psxpak]

Originally Posted by Accelo

New Proportioning valve arrived. China but I suspected that.
What's funny part is the quality control sheet that arrived with the valve.
I'm hopeful this one doesn't leak, in two places!

I put a new valve like that in my 72 and it leaks out the front a little bit. I did it in the process of trying to get my rear wheels to stop locking up. I ended up adding a wilwood adjustable valve to the rears. It honestly didnt help much.

[SRU1436]

Originally Posted by Accelo

New Proportioning valve arrived. China but I suspected that.
What's funny part is the quality control sheet that arrived with the valve.
I'm hopeful this one doesn't leak, in two places!

Let me know how it goes, my original on the truck leaks?

Thanks

[PbFut]

Have you pulled the drums and inspected things? I had an issue with the rears locking up many years ago. Shop said the slave was leaking and getting onto the shoe. Seems contrary and I would have thought otherwise. They replaced the "leaky" slave and it stopped. But could be they saw me coming adjusted the brake and sold me a few extra parts. Just offering up a possible idea that I can't fully confirm. Maybe too much iced tea this afternoon.

[psxpak]

Originally Posted by PbFut

Have you pulled the drums and inspected things? I had an issue with the rears locking up many years ago. Shop said the slave was leaking and getting onto the shoe. Seems contrary and I would have thought otherwise. They replaced the "leaky" slave and it stopped. But could be they saw me coming adjusted the brake and sold me a few extra parts. Just offering up a possible idea that I can't fully confirm. Maybe too much iced tea this afternoon.

oh man i dont wanna hijack the thread but oh ya ive replaced everything but the hard lines and the booster. ive just learned to leave a good long safe distance between me and the vehicle ahead of me. stops good with a ton of brick in the back though!

[Accelo]

I just installed the replacement valve. I am moving forward. This "New" Proportioning only leaks in only one place not two like the first one. It is leaking from the Metering valve. I am considering purchasing just the metering valve for $13 + shipping. Running out of options.

Man am I wishing I had went with the Wilwood brakes kit about now. I traded price for a headache than will not go away.

[SRU1436]

Bummer, sorry to hear that.

I heard this is supposed to be good.

https://piratejack.net/copy-of-14041...MaAlqHEALw_wcB