Brake conversion for a 66 - proportioning valve?
 

In the nineties I bought my 66 C10 and it didnt have power brakes. It was a single MC down to the drums. Many years later around 2008 I had a local custom shop do a front disc conversion for me. They bought a kit and installed it and it worked great. In 2015 I decided to do a tear down and fix up my truck and I disassembled. Recently I started buying new lines and fittings, even a new MC and was going to put it all together. I plan to run the lines from a 1/4 nickel/copper coil I bought and do the flaring myself. When I went to look for a good guide to run the lines I saw for a 1972 c10 that there is a proportioning valve in the diagram on LMC trucks site here

https://www.lmctruck.com/1967-72-che...rake-line-kits

My truck since I have owned it has never had a proportioning valve. I imagine its fine not to have it as I drove this truck for more than a decade and had no issues with braking. But if adding it in makes sense and I can get help identifying the right part to order I will plan to include it. The dual MC I just bought was a new AC Delco 18M1036 from a 1972 C10. When I look at Rockauto for the proportioning valve for 1972 C10 it doesnt show one.

Whats the right way to find the part if I should include it?

Here are some pics of the single MC when I bought it and the Dual MC after the conversion.

Re: Brake conversion for a 66 - proportioning valve?
 

https://www.summitracing.com/parts/wil-260-11179/ I used this one. It was cheaper back then and worked good. This is how I mounted it. Didnt feel like hiding it.

Re: Brake conversion for a 66 - proportioning valve?
 

All disc/drum or disc/disc vehicles should have a 'proportioning' valve.

Re: Brake conversion for a 66 - proportioning valve?
 

Is there a best way to pair up the MC i bought with a proportioning valve? Hoping to get the right match if it matters.

Re: Brake conversion for a 66 - proportioning valve?
 

I believe a proportioning valve or (combination valve) as GM calls them from a 73 - 79 truck should work fine. There's not really that much to them. I can't say for sure about your set up - I used EVERYTHING from a 73 C-10, the master, ALL brake lines and the proportioning valve and installed the proportioning in the factory location for a 73 - 79 C-10. You will also need the little tool to hold the proportioning valve centered when bleeding the brakes. That's the little POL tool in the last picture.

Re: Brake conversion for a 66 - proportioning valve?
 

I did the same thing. Got lines and prop valve from a square body donor.

Re: Brake conversion for a 66 - proportioning valve?
 

I used everything off a 79.
I ended up also adding an adjustable proportioning valve. My backs kept locking up before the front. The adjustable is also helpful when you have an empty bed vs a load in the bed.

Re: Brake conversion for a 66 - proportioning valve?
 

In my case with the MC I just bought I wonder if I shouldnt return it and buy a whole system. I may call inline tube tomorrow and see what they would sell me to work with what I have, and the whole system option as well. I would like to keep the lines going as they were but if running them via the front is a must Ill rethink the routing. Question though, in either case is that loopy coil off the MC done for a functional reason?

I searched and found a few prop valves that were results for a 73. Be great to know if they actually would be a proper prop for what Ive got going on.

https://www.amazon.com/Team-Performa...=3149014980001

https://www.summitracing.com/parts/c...eviews/?page=2

Re: Brake conversion for a 66 - proportioning valve?
 

The prop valves should be the same for all GM vehicles. When you are looking find one that includes the mounting bracket and the little pre-bent lines that connect to your MC. I got mine with an entire disc conversion kit from POC. The booster, MC and prop valve came from CPP. Mine looks just like the one 64 shortbox posted. Just make sure it is for disc/drum. The one I linked below has everything (bracket & lines) including the plug to put in the brake sensor port to keep the valve centered when bleeding. The bracket should mount to the mc/booster bolt on the drivers side and them bolt to the prop valve itself. The lines will also hold it in place. Then you will connect 2 3/16 lines to the front of the prop valve to the right and left front discs. The port on the back will be for connecting the 1/4 line to the rear drums.

https://www.jegs.com/i/JEGS/555/631302/10002/-1

Re: Brake conversion for a 66 - proportioning valve?
 

The AC Delco I had ordered has me wondering if its correct for disc/drum. It was showing to be a match for a 1972 C10. The reservoirs are the same size though..shouldnt the secondary reservoir be smaller than the primary?

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Re: Brake conversion for a 66 - proportioning valve?
 

I have a 1/2 ton squarebody combination valve in my 66 c10 Suburban. It is mounted inside the driver's side frame rail, rather than the front crossmember like it was in the squarebody. Thats mainly because the crossmember is different. Front disc brakes are from a 76 1/2 ton.

Re: Brake conversion for a 66 - proportioning valve?
 

Before I got to cutting, flaring and bending I drafted the lines pretty crudely to see if this is right. I guess coiling the lines of the prop valve would be best to run underneath the setup to make sure it doesnt interfere with the steering column and the inner fender panel. Never done this before, does this check out?

Re: Brake conversion for a 66 - proportioning valve?
 

Isn't there 3 output ports on that proportioning valve? The stock prop valve has 3. Left front, right front and one for the rear. At the rear axle there is a splitter block.

Re: Brake conversion for a 66 - proportioning valve?
 

You can do the coils, but they aren't necessary. They just made it easier to install on the production line.

Re: Brake conversion for a 66 - proportioning valve?
 

Thanks Big Moe, I looked at the install instructions on the manufacturers site but it didnt have directions on how to run the lines other than the pic ill attach. That top plastic part, Its supposed to connect to the dash indicator I think. I have a new wiring harness I ordered so it may have a way to connect. Not sure if I have any lights will trigger though.

https://www.getdiscbrakes.com/pub/me...ions/AFXDC.pdf

The previous set up I had without the prop valave did a t connection for both of the front sides into one port on the MC. Glad I asked here, I called the tech line and it rang for 3 minutes.


Thanks Jay, I may add the flex coils just in case I tug too much or hit a bump that jars the connections loose.

Re: Brake conversion for a 66 - proportioning valve?
 

A spray can is the perfect size for looping the coils around. I also like using a front disc brake rotor for doing other bends. Three different radii (outer, hub, center bore) to bend around, and you can also use the lugs to hold the pipe to make tight bends. I have a tubing bender, but never really use it. I do it by hand, on the rotor, and on my knee.

Re: Brake conversion for a 66 - proportioning valve?
 

Dang, well if I have to run the two lines individually for the left/right front off the prop valve I have it would look like this. Maybe there is a better routing. The coils I cant see doing 3, hopefully the bracket on the booster will keep things stable enough. The lines wouldnt be 90 degrees thats just the quick pen tool I used, the bends would be rounded.

Re: Brake conversion for a 66 - proportioning valve?
 

You could mount the prop down on the frame and just run two lines.

Re: Brake conversion for a 66 - proportioning valve?
 

You don't have to run two separate lines to the front, if you don't want to. You can run a single front line and T off of it for the left front brake and then terminate at the right front brake.

Re: Brake conversion for a 66 - proportioning valve?
 

Thats what I was thinking originally, and I guess just plug off the extra prop valve port that is on top (the one i have a yellow line going from the top prop port to the passenger side). Is that ok to do you think? I would think the same amount of pressure would be coming out of the one port if the other was sealed off and just supply the two fronts the same way...just from a tee instead. I was trying to contact the manufacturer and ask but they never answer.

Re: Brake conversion for a 66 - proportioning valve?
 

If you're going to use a prop valve (and you should with your setup), plumb it correctly and don't use a T for the fronts. Use it as designed.

Re: Brake conversion for a 66 - proportioning valve?
 

Yes, it will have the same pressure. Mine was plumbed exactly the same, with one line coming from the distribution block, and then T'd. Never an issue. IMO, it makes for a cleaner and easier install. Yes, you just plug the port you do not use.