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Proportioning Valve Rebuild

T

texarback

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I have this AC Delco Proportioning Valve (Part # 172-577) that works fine except the "O-Ring", if you call it that, is split.

Does anyone know where to source parts for these things? I assume they were meant as a consumable that should be replaced if a failure occurs as I can't find anything when I google the historical documents.

Also, anyone know how to remove the other end of the valve that has the rubber protector on it? I don't know if it screws out or if it is press fit (doubtful as I would assume pressure would push it out).
IMG_6434.jpgIMG_6435.jpgIMG_6436.jpgIMG_6437.jpgIMG_6438.jpg
 
Never had one apart, that's cool, thanks for sharing.

I *think*, if you have no luck with that vendor, they may be called square cut o-rings. I do see "washer rings" as well, but that may be a European thing.
 
Try a place like “Motion Industries” for square cut o-rings.
Or any industrial fluid power hydraulics specialist kind of place - you’d be surprised what they can get.
 
Looks like all the ports are threaded. There are a series of rebuilds on this site - may be helpful: https://www.musclecarresearch.com/articles

combo.JPG


Combo_Valve.jpg
 
Thanks for all the responses.

Here is what I’ve found:

I’ve traded emails with Scott at Muscle Car Research and also Jim at Old Auto Restoration up in Pennsylvania.

Both said they believe that the broken seal is a u-cup design. Scott mentioned that he didn’t think this seal was original and he thought the valve may have been repaired in the past. I’m 99% sure it has not been repaired before. I know my grandpa and I am confident that he never messed with it before. Jim said he didn’t have one either but could repair it if I need to send it to him.

I’m going to see if I can find one through McMaster-Carr. They have them and it is a matter of finding the right size.

The other issue is getting the metering valve out of the other side. I know that there is a metal ring that needs to be removed before it can be unscrewed from the housing but so far I have been unable to get it out.

I’m leaning towards not messing with it as the valve does work fine. If I can get the new seal then it should be good to go.
 
In my years as a daily wrench the only time I ever fooled with counter balance proportioning valves was to recenter them, after a hydraulic system failure, or up date one when converting the brake system to discs or a single circuit master to dual circuit.
 
texarback said:
Thanks for all the responses.

Here is what I’ve found:

I’ve traded emails with Scott at Muscle Car Research and also Jim at Old Auto Restoration up in Pennsylvania.

Both said they believe that the broken seal is a u-cup design. Scott mentioned that he didn’t think this seal was original and he thought the valve may have been repaired in the past. I’m 99% sure it has not been repaired before. I know my grandpa and I am confident that he never messed with it before. Jim said he didn’t have one either but could repair it if I need to send it to him.

I’m going to see if I can find one through McMaster-Carr. They have them and it is a matter of finding the right size.

The other issue is getting the metering valve out of the other side. I know that there is a metal ring that needs to be removed before it can be unscrewed from the housing but so far I have been unable to get it out.

I’m leaning towards not messing with it as the valve does work fine. If I can get the new seal then it should be good to go.
Click to expand...
I am sorry but this is not a square cut o ring, it's a seal.
It's actually wedge shaped not square.
It's like seals in a master cylinder for brakes or clutch.
I have rebuilt a few of those but not this.
You might be able to find some the right size if you find an automotive supply store that sells rebuild kits for brakes and is willing to work with you.
I don't have the patience or time to do this anymore but I used to enjoy it in my 20's and 30's
 
Here are a few better pictures of the ring. It definitely looks like a U-Cup ring.

McMaster-Carr seems to have them. I just need to figure out the right size.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com

I also got the metering valve out from the other end. I'll post pics of it when I get home. The hardest part was getting the metal ring out. It has rust-welded to the body.

Ring 1.jpgRing 2.jpgRing 3.jpgRing 4.jpg
 
Why not just get an entire new assembly? This is something that I would not be wanting to mess with.
 
I've yet to have an issue with one of these, I'm of the mind to leave them be as well. If opening one up, you'd probably want to ensure the bores are all spotless, and replace every seal. They look to be the same design seals in auto trans, they harden up and tear pretty easily after time, heat, and crud/rust that happens when brake fluid isn't changed.
 
wazzabie said:
Why not just get an entire new assembly? This is something that I would not be wanting to mess with.
Click to expand...

Why buy a new assembly when you can rehab the old one? We do the same thing with our transmissions, engines, steering gear boxes, power steering pumps, etc. Why throw away a perfectly good part because a seal is bad?

Edit: I suppose most do throw them away and buy new. There is very little in the way of actual rebuilds on the interwebs.
 
texarback said:
Why buy a new assembly when you can rehab the old one?
Click to expand...
I tend to agree, as I don't like this throw-away society (sell me a $1200 lawnmower that won't last more than 5 years, instead of a $2000 one I can maintain indefinitely).

But there's always the question of what's worth the time doing. Curious how many hours of research and teardown this was and price of a seal kit, compared to a remanufactured valve (is it available?). I do agree it's nice knowing exactly what's in there and that it's built with good parts, vs rolling the dice on reman, especially with all the bleeding required.
 
I certainly see that point of view and hope I didn't come across as snarky with my reply. This truck is down to the frame right now so I'm rebuilding everything where I can. It is a hobby but you are right, time and money are certainly a factor for most projects. This one is about restoring the things back to factory as best I can. So far I've rebuilt the steering box, power steering pump and this valve. I'm currently working on the shifter for the transmission case. I did buy a new water pump as from what I can tell it takes a bit of technical expertise and equipment to do the rebuild properly. I have neither. :)
 
texarback said:
Why buy a new assembly when you can rehab the old one? We do the same thing with our transmissions, engines, steering gear boxes, power steering pumps, etc. Why throw away a perfectly good part because a seal is bad?

Edit: I suppose most do throw them away and buy new. There is very little in the way of actual rebuilds on the interwebs.
Click to expand...
I'm all for rebuilding and I would rather have original parts then aftermarket. For me personally I would attempt a rebuild of the brake proportioning valve but I would have alot of concerns if I did the rebuild correctly. That is where I wonder rebuild or buy remanufactured.
 
I'll post a pick later this evening but it is painted and all back together minus the one seal. I just need to order it. It looks like it should still work fine. Glad to have it all cleaned up and now moving on to the next project.
 
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