Proportioning/Metering Valve Suggesting for Rear Drum/Front Disc Brakes

[1970Cuda]

Background:
I converted my 1970 'Cuda from drum brakes to drum (rear) and disc (front). In doing so, I replaced the front spindles to later model A-body (73 - 76) units. And to keep it looking somewhat original, I went with a new master cylinder that was manual, not power assist.

The issue:
I am using a reproduction proportioning/metering valve and I cannot get it to seal. I am running steel lines from the master cylinder to the valve and those are fine, with no leaks to the inlet. Also, the stainless body lines (front and rear) seal and it doesn't leak there either. What I am finding is that it is leaking from odd places. From the pictures you can see where I circled the leak points. Basically, at places you wouldn't think it should leak.

The pictures show the first valve and the leak points. The second is a closer view of one of the leak points and the third is simply the overall configuration for reference.

The Ask:
I purchased two of these valves from the same source and they both leak. I don't want to purchase a third one from the same source, so I am wondering if anyone knows of a high-quality replacement proportioning/metering valve of a similar style and configuration? I am trying to make progress and don't want to keep revisiting this issue again and again. Thanks for any assistance or suggestions on a source.

[mtull]

I rebuilt my original brake valves but for full disclosure I haven't pressurized the brake system yet (fingers crossed they don't leak).  I bought the new seals from Scott at https://www.musclecarresearch.com/.  He was very helpful.  The biggest problem I had was disassembly of the brake tee and metering valve (metering valve requires special socket).  I used the following rebuild kits:
- brake tee kit 
- metering valve kit
- proportioning valve

I've seen used brake tee's and proportioning valves on eBay for decent prices.  I haven't seen many used metering valves for some reason.

Regarding the brake tee disassembly I found a 5/16 socket in my cordless drill worked best (for me at least).  I set the drill clutch on the lowest setting and gradually increased power and clutch as needed.  I started at 1 and worked my way up to 8 or 9 before it broke loose.  I tried a steel box end wrench first but it started to round the corners so I stopped immediately. I'm pretty sure Scott's direction even tell you not to use said wrench.

I found the easiest way to reassemble the metering valve was put it in a vice and compress the spring in order to insert the retaining clip.  Maybe have some cardboard standing vertically around your vice in case the assembly slips out.

If I can do it I'm sure anyone can.  Worse case send them to https://brakeandequipment.com/

I'm a little embarrassed of my pics,  the brake valve rebuilds are short term and will be disassembled again in order to properly plate the steel brackets.  A fellow forum member has another metering valve assembly he's willing to sell me.  As you can see my original had to be modified as the machine shop tore it up to remove it.

[1970Cuda]

Hi mtull,

Great write-up and very detailed explanation on what you did to restore your brake and metering valve! Definitely well thought out and planned. I will definitely look at the resources you posted to see if they can solve my problem. Again, I really appreciate you taking the time to provide some feedback on my post and dilemma.

[Cuda_mark]

I had some leakage issues with 2 different parts from inline tube. I finally gave up on them and sourced an original part and the problem was solved.

[1970Cuda]

I agree Cuda_Mark on Inline Tubes. I, too, had a big issue with my rear line on my 'Cuda. It was leaking at the metering connection and I could not get it to stop. I had to remove it and replace it with an sstubes (formerly Fine Lines) tube. Upon inspection, I noticed that the flare fitting was improperly done and it was never going to seal. I will never purchase from that company again. Unfortunately, sstubes only carries a limited number of products for E-bodies.

I might go the route of buying a used proportioning valve/metering valve and just rebuilding it, but I would rather purchase a quality new part.

[mtull]

I noticed that the flare fitting was improperly done and it was never going to seal.

Sadly, I recently placed an order with SS Tubes and found the same problem and many more.  I'll start a thread outlining my findings soon.

Regarding your comment: "I would rather purchase a quality new part", a quick Google search returns many results on leak complaints.  I've wondered if said brake valves are manufactured by one vendor or multiple?  Is the issue early vs. later production runs?  Very few folks state they have no problem with leaks so I wonder, what's different with their parts vs. all those that leak?  Finding a good one seems to be random luck.

[1970Cuda]

mtull - I appreciate your update on sstubes. I have had good luck with this supplier in the past, but maybe its time to start making my own lines going forward or at a minimum, double-checking the fittings and correcting them after receiving them.

In the meantime, I've been working with the supplier on my issue, and we think we might have found the problem. It's our belief that the the plug isn't seating on the chamfered fitting on the proportioning valve. So we are creating a "work around" with a modified steal tube to seal it. It won't look pretty, but it will work and at this stage, I want to get moving on other aspects of the project.

In parallel, I will start looking for a good, used valve and rebuild it myself. That way, if this solution doesn't work, I will have another one already queued up.

[mtull]

I have had good luck with this supplier in the past

I'm hopeful the quality control issues I found are one-off.  Other folks on the forum have also had good luck with them.  The vendor did provide some assistance.
Regarding the potential plug seating issue please let us know how it goes as it may resolve the leak problem for many.  Fingers crossed for you, good luck!

[71vert340]

Nope. I purchased a metering /proportioning valve just like the one shown. It leaks about a drop every 2 days. I'm going to take the top apart and replace the copper washer with a new copper washer. I may use a sealant on both sides of the copper washer and let it set up good. I also got new brake lines from Inline and had some small leaks. I finally bought the flaring tool kit for double flares along with some brake line tubing and nuts. I solved all the brake line leaks. I had to replace two lines (short ones) One last leak to go on the valve. I still have the original valve and may go the rebuild route.
 Terry W.

[1970Cuda]

Hi 71vert340 - As my picture shows, mine leaked in exactly the same place you mentioned and no matter how tight I made it, it still leaked. And I also tried a new copper washer too, and that did nothing at all. I am thinking it's a design flaw with the new reproductions. I would like to see how the original is made at that matting surface and I am thinking that it's a different design.

I am going to search for an original part and simply restore it. And I am with on the building the lines myself or at a minimum, simply buying a double-flare tool and correcting any issues with purchased lines. It's pretty lame to have such poor manufacturing quality.

[1970Cuda]

So the fellow that has been assisting me with fixing the issues with my proportioning valve issues recently sent me an updated plug to replace the original one that was leaking. He has been super helpful with trying to help solve my issue.

I installed it yesterday and am doing a test run with it now. Here is the update plug for reference. I will update the thread after my testing is done.

[71vert340]

I took my new metering/proportioning valve apart at the leak. I'm a machinist by trade and I saw the problem right away. The washer is a narrow washer across the diameter and is flat. The brass metering block has a chamfer(taper) cut from the sealing surface down to the threads. It's a very narrow lip for the washer to seal against. The washer should have been cut with one side chamfered and one side flat, giving more sealing area. I had nothing to lose so I cleaned the mating surfaces of the washer and the block. I then carefully used the RTV gasket maker on both sides of the washer, being careful not to get any on the threads. I reinstalled the fitting with the copper washer/RTV and tightened. I'll let it dry for 3 days and I'll bleed the brakes and check for seepage. I'll let you know the results. It could be if an O-ring was used that is resistant to brake fluid, it would be a better solution.
 Terry W.

[1970Cuda]

Terry - I appreciate your detailed explanation of the issue and wanted to follow-up to see if your fix worked. Mine too leaks at the same place, but a bit slower than you mentioned.

However, I was waiting to respond to this thread, because I am still testing the plug fix and am still assessing whether it worked or not, but I am more optimistic than before.

Still, I will search out my friends and this site for a used, serviceable proportioning valve and just rebuild it to have it on hand if the leaking becomes worse. The metering valve doesn't seem to leak at the moment. So with the rebuilt used valve and the new metering valve, at least I can have some assurance that my issue will be resolved.