Help With Proportioning/Combination Valve Identification

[dmjlambert]

Hi Keith! Is there anything in the charts that would explain some 1971 trucks don't have the metering valve while it appears other 1971 trucks and later trucks had them?

[cericd]

Okay, here's my latest combination/prop valve. I'm told it came from a '72 C/10. It's a Bendix 0411 that has the following numbers on it. The side opposite the Bendix 0411 stamping has 10 230 on it. BM0238 is stamped on the front above the rubber cap. Not sure what any of that means.

I know there were multiple manufacturers of the brake components on these trucks, most commonly Delco/Moraine and Bendix. It got me thinking, would they have only used a Bendix valve with a Bendix booster and the same with Delco? I searched the forum and found some pics of Bendix valves with Delco boosters, which is what I would have if I use this with my current setup. The were also several pics of Delco valves with Delco boosters which is what I was going to go with if I could find one. Also, I know that anything could've been added or swapped in over the last 50 years. But... since I found evidence of trucks that look pretty original with a Bendix valve and a Delco booster, maybe I'll have this one rebuilt and run with it.

[cericd]

Here are some pics I got from another member of a setup off a 59k mile C20 which had a Bendix valve and Delco/Moraine booster.

[pjmoreland]

Originally Posted by cericd

Okay, here's my latest combination/prop valve. I'm told came from a '72 C/10. It's a Bendix 0411 that has the following numbers on it. The side opposite the Bendix 0411 stamping has 10 230 on it. BM0238 is stamped on the front above the rubber cap. Not sure what any of that means.

I know there were multiple manufacturers of the brake components on these trucks, most commonly Delco/Moraine and Bendix. It got me thinking, would they have only used a Bendix valve with a Bendix booster and the same with Delco? I searched the forum and fount some pics of Bendix valves with Delco boosters, which is what I would have if I use this with my current setup. So maybe I'll have this one rebuilt and run with it.

I'd be interested to see what the big spring looks like under the rear outlet, if you are inclined to open it up.

[cericd]

Yeah, your post from earlier had me wondering too. I tried but didn’t want to force it and damage the nut. Also I saw somewhere that the only lubricant you should use on these fittings is brake fluid??? I guess it wouldn’t matter since I plan to have it rebuilt. Thoughts? I’d like to see what’s in there myself.

[pjmoreland]

I clamped mine in a vise between two pieces of wood, and then I used a six-point socket to loosen that nut.

[MikeB]

If you find a company that knows how to properly rebuild these stock valves, please let me know. On the website of a company I heard about (maybe in Maryland?), I used a "contact us" form to ask them the price and turnaround time to rebuild mine. But I never did hear back from them.

[cericd]

Originally Posted by MikeB

If you find a company that knows how to properly rebuild these stock valves, please let me know. On the website of a company I heard about (maybe in Maryland?), I used a "contact us" form to ask them the price and turnaround time to rebuild mine. But I never did hear back from them.

Hey Mike, the two that I've run across while searching are White Post Restorations and Old Auto LLC. I don't have any experience with either of these companies but another member on here dmjlambert, has had one restored by White Post and seems to be pretty pleased with the results. The other company, Old Auto LLC, has videos on youtube of them rebuilding a few different valves.

White Post Restorations - https://whitepost.com/brake-sleeving...ding-services/

Old Auto LLC - https://oldautorestorations.com/

Old Auto LLC youtube videos - https://www.youtube.com/@oldautollc2...ebuild%20valve

[MikeB]

Chris, thanks for the info. It was White Post who I contacted via their website. I'll call them next time.

My combo valve is the original from a 71 or 72 truck, I assume a C10. Got the valve, booster, and brackets in the mid-90s from a junkyard that specialized in Chevy/GMC pickups. As far as I know it's working well, but I did have to replace the switch because it was literally worn out, causing the warning light to flicker.

I'll be bleeding the system and replacing hoses when the weather cools down here in north Texas. In the meantime, I'll look into ways to check brake pressures. Any idea what the pressures should be?

[dmjlambert]

I remember White Post email communication to be not so good. I was more impressed with what they had to say on their website, so I took a chance on them, and I'm pleased with the results. I believe the valve functions fine. I asked if they paint or coat the valve with something when they are done cleaning up the outside, and they said they put an epoxy coating on it. I was barely able to tell the difference between bare cast iron and their coating color, and I believe they missed a couple of spots, so their attention to detail in painting is imperfect.

[Keith Seymore]

Originally Posted by dmjlambert

Hi Keith! Is there anything in the charts that would explain some 1971 trucks don't have the metering valve while it appears other 1971 trucks and later trucks had them?

My observation would be that manual brake trucks did not get metering, but all power brake did.

No explanation is given.

K

[Keith Seymore]

Originally Posted by cericd

I'm sure from the factory, the prop valve was tailored to the specifics of the truck but today, the aftermarket prop valves don't list these specs and seem to fall into two categories, disc/drum and disc/disc applications. I'm trying to get the proper OEM prop valve and have it rebuilt to factory standards.

Keith, would you happen to have documentation that shows what meter/split/slope I would need for my application. I am trying to keep my truck as stock looking as possible so there aren't any suspension/big brake mods to take into consideration.

My truck is a 1970 SWB C/10 with a 307. What other info would you need to look up the meter/split/slope specs for my truck? Thanks.

It doesn't seem to show any kind of metering or proportioning on the truck; unless it is part of the master cylinder "power head" assembly and the detail is not broken out.

K

[Keith Seymore]

One other consideration is that General Motors would have to meet all federal regulations regarding brake performance, or we couldn't sell that combination.

In some cases the design margins were so tight that we would ask for a specific technician to drive the truck during development or validation testing.

Aftermarket component suppliers would not have to meet those rigorous requirements.

K

[cericd]

Thanks Keith, I don't know why I referred to my truck as a 1970 SWB C/10 with a 307. I mean, that's what it is but the braking system is now more akin to a 1971 SWB C/10 with a 307. I have added factory style front disc brakes and a restored Delco/Moraine from a 71 C/10. I currently have an aftermarket combination/prop valve and I would like to replace it with an appropriate Delco, Bendix or Kelsey Hayes valve.

[Keith Seymore]

Originally Posted by cericd

Thanks Keith, I don't know why I referred to my truck as a 1970 SWB C/10 with a 307. I mean, that's what it is but the braking system is now more akin to a 1971 SWB C/10 with a 307. I have added factory style front disc brakes and a restored Delco/Moraine from a 71 C/10. I currently have an aftermarket combination/prop valve and I would like to replace it with an appropriate Delco, Bendix or Kelsey Hayes valve.

Hopefully the email I sent with the '71/'72 information will be helpful.

K

[cericd]

Originally Posted by Keith Seymore

Hopefully the email I sent with the '71/'72 information will be helpful.

K

Much appreciated Keith.

[cericd]

Here's some more info regarding the picture of Andy4639's valve I mentioned in post 15 of this thread.

I heard back from Andy and he informed me that the valve was original to the truck which is a '71 1/2 ton lwb which originally came with manual front disc/rear drum brakes. So, it's starting to look like the type of combination valve, without the rubber cap on the front, (in my first post) came on trucks with manual disc/drum setups.

Andy's pic I showed in post 15 of this thread was from 2009. I found a more recent picture of his master cylinder setup from 2020 that shows he had switched to an aftermarket, (brass), valve and a different booster. This is beyond the scope of what I am trying to figure out (what valves came from the factory with a power disc/drum setup) but I thought it was worth mentioning in case anyone starting digging into the forum and ran across that info.