Need disc brake kit prop valve rebuild info help

[69_Sport]

I installed this proportioning valve with TBP's power disc brake kit:

https://www.tomsbroncoparts.com/product/2625K-disc-brake-proportioning-valve-with-bracket-kit

Now it leaks out the front under the little rubber cap, and I need to fix it. I'd like to order a rebuild kit, but I don't know the application. I don't see any rebuild kits on their web site. I'd like to buy it locally if I could.

Does anyone know the oem application on this proportioning valve or a source for a rebuild kit?

Thx!

Doug

 

[B RON CO]

Hi, these proportioning valves are notorious for leaking.
I'm surprised the vendors can't get a good reliable source for them. This leaking problem has been going on for years. I went through 3 of them until I just got one from Napa. I wish I saved the box to have the part #.
Good luck

 

[69_Sport]

I wish I saved the box to have the part #.
Good luck

I wish you had, too!

Did you try replacing the internal seals? I'm not entirely sure what I'll find under the rubber cap.

 

[69_Sport]

So some online sleuthing led me to guess that the prop valve is either a '71-'77 or '78-'88 GM Truck unit. Online pics look identical.

Anyone know if either of these is correct, and can a rebuild kit be bought somewhere?

 

[B RON CO]

Hi, I don't think there is any fixing a proportioning valve.
Before I got my good one at Napa I use to always look under the Bronco for a puddle. Pretty Bad.
My guy at Napa found a good one for me in the old parts book. It could be GM, but make sure it is from a disc/drum car.
I told him about the problems I had with the leakers and he said if this one leaks, bring it back.
Good luck

 

[rmcmillan]

I have the same proportioning valve that I purchased from Tom's Bronco which also leaked. I ordered a replacement kit from Summit Racing. Part # CLP-PVMVK-T for $12.99

 

[69_Sport]

I have the same proportioning valve that I purchased from Tom's Bronco which also leaked. I ordered a replacement kit from Summit Racing. Part # CLP-PVMVK-T for $12.99

Is it too much to assume the kit fixed the leak?;D

 

[69_Sport]

I have the same proportioning valve that I purchased from Tom's Bronco which also leaked. I ordered a replacement kit from Summit Racing. Part # CLP-PVMVK-T for $12.99

I just ordered one. Thanks. I knew someone had to make a rebuild kit.

If that doesn't work, I'll get a replacement valve at NAPA. I just hate to loosen all the lines, the bracket, and swap it out if I can just replace the seals. It only has about 1000 miles on it. Plus, how do I know that the new one is any better?

 

[DirtDonk]

Good of you to just go ahead and get a new one on your own. But, and not to put words in someone else's mouth here, I would think you could get a replacement from the company you bought it from at no additional cost to you. Unless it's been years since you purchased it of course, there should be some kind of support for it.
We've had to send out quite a few over the years, including both entire valves, and in some cases just the new delay valve (the thing under the rubber boot) that leaks.
Other times customers have just made the leak go away on their own. New o-rings, or seals would sometimes take care of it.

I'm not sure if it's always the same place that leaks on these, but it looks like that kit that rmcmillan linked to above covers all the bases.

Bottom line though, is that if it's new it should not leak and you should not have to pay for a new part to fix it.
And while it's not all of them that leak, it was getting bad enough that we don't even list them separately anymore and instead are recommending the manually adjustable valves more and more often now. Kind of what I've been doing for years anyway. After about the second one had to come back with a leak!

Most of our new kits, like the MOAB systems, come with the manual valves now. And I've never heard of one failing or leaking.

Good luck.

Paul

 

[DirtDonk]

Another question 69_Sport. Where did you mount your proportioning valve?
I don't remember if I've ever asked any of our customers that have leaks, whether or not they're mounted down by the exhaust system similar to where the factory mounted them.
And if so, whether they had headers or not.

Reason I'm asking now is that I've always recommended that anyone with headers mount their prop valves up much higher than normal, out of the way of the additional heat that emanates from the header tubes.
I'm pretty sure that's not the main underlying issue, as we've seen them leak even when mounted up by the mater cylinder (I think Doug even had trouble when he was building the '68 that I now have) too. Which is a double-bummer, since it's almost guaranteed to leak on shiny new paint on the body instead of the frame!

Anyway, just curious where yours was mounted.

Thanks

Paul

 

[69_Sport]

Paul

Mine is mounted in the stock location.

And no, I don't have headers. Stock exh manifolds.

You may be right about my expectations on this problem, but for $12.99 I'm gonna try it.

I really don't want to replumb the brake lines to install a manual valve. If this kit works, I won't even have to undo any lines...fingers crossed.

Doug

 

[DirtDonk]

Definitely. And keeping the same valve instead of trying even another version of the same style might end up with different size fittings as well. Meaning you'd have to re-do the lines even if it looked the same.

I was mentioning the other type more for future reference because I don't like redoing brake plumbing either!
But the bit about headers was pertinent no matter what, and I'm glad you don't have to move it either. You should be fine with stock manifolds, but some of us still put a heat shield between the two anyway. Sometimes you just don't want extra heat in the brake fluid no matter what.

Good luck.

Paul

 

[sykanr0ng]

One or two members here have mentioned that when they took their proportioning valves apart to try to fix leaks they found that the manufacturer had not deburred the internal parts or holes in the body and the sharp edges cut the seals.

 

[73azbronco]

That stock position for distribution and stock proportioning valve really needs some insulation from headers or even stock manifold in my opinion. pretty cheap and easy fix.

 

[72Sport]

Paul

Mine is mounted in the stock location.

And no, I don't have headers. Stock exh manifolds.

You may be right about my expectations on this problem, but for $12.99 I'm gonna try it.

I really don't want to replumb the brake lines to install a manual valve. If this kit works, I won't even have to undo any lines...fingers crossed.

Doug

Most car manufactures recommend flushing brake fluid every few years to get the old brake fluid out of the system that has absorbed water. Before you rebuild the valve you might flush your brake system with new brake fluid. When I was changing to disc brakes I thought I could go to a wrecking yard and get a proportioning valve and rebuild it. That was a waste of time. The used ones were so rusted on the inside I couldn't find one I could take apart. Cast iron rusts very easily. I ended up buying a new valve from a Ford dealer (years ago).

I have run stock manifolds with the P valve mounted up high on the front spring mount. I put a piece of aluminum spaced away from the P valve to keep the heat away from the P Valve. I think it has been on the Bronco about 10 years. So far so good.

 

[69_Sport]

One or two members here have mentioned that when they took their proportioning valves apart to try to fix leaks they found that the manufacturer had not deburred the internal parts or holes in the body and the sharp edges cut the seals.

This is likely my problem.

The proportioning valve is new. Not a heat/ header problem.

Unfortunately I can't tell where it was manufactured so can't guarantee replacement won't result in the same issue.

I'm going to carefully replace the plunger and seals and cross my fingers. If this doesn't work, then I will be replacing the valve.

No one answered the question as to what to buy for a replacement. 71-77 GM truck or 78-88 GM truck????

 

[72Sport]

When you rebuild you proportioning valve make sure you use the seals/o'rings are made of the correct material. I can't find my book but I believe that EPR or Ethylene Propylene is the correct material for brake fluid. Buna N which is used with motor oil, trans fluid etc will swell when exposed to brake fluid. I don't think your local auto parts will have EPR o'rings.

Go to the Napa website and look at proportioning valves for 76,77,78 and 79 Broncos. I used a valve for a 78 Bronco when I added discs to the front of my Bronco. Why? because the Ford dealer did not list a 76 or 77 Bronco P valve.

https://www.napaonline.com/en/p/NMAM552 This link is for a 1977 Bronco P valve. It says it is not an exact fit. May have different size fittings. I don't think they would show it fits a 1977 if it caused some sort of function problems.

 

[DirtDonk]

...No one answered the question as to what to buy for a replacement. 71-77 GM truck or 78-88 GM truck????

Neither one?
Probably few, if any members here have done it that way. Most prop/combo valves are sourced new through the usual culprits for brake parts. And those are all aftermarket brand new parts with no mention of what they're patterned after.

And I don't think you'd want to use a pickup truck as your donor for a brake proportioning valve anyway. The balance and needs of a pickup truck are completely different than a Bronco.
Maybe they're all using the same ratio of front vs rear brake bias though? I don't know if every combo valve is the same other than the port sizes, or if they're all different for each vehicle. But it would make sense that it was different for each vehicle.

GM was pretty good about using the same stuff over many vehicle lines though, so perhaps they at least used all the same fitting sizes. Unlike Ford which changed the tube fitting sizes on practically every application of proportioning valve. Keeping you from just easily swapping one from an '89 pickup into a '69 Bronco.
That would be way too easy!

Paul

 

[69_Sport]

Neither one?
Probably few, if any members here have done it that way. Most prop/combo valves are sourced new through the usual culprits for brake parts. And those are all aftermarket brand new parts with no mention of what they're patterned after.

And I don't think you'd want to use a pickup truck as your donor for a brake proportioning valve anyway. The balance and needs of a pickup truck are completely different than a Bronco.
Maybe they're all using the same ratio of front vs rear brake bias though? I don't know if every combo valve is the same other than the port sizes, or if they're all different for each vehicle. But it would make sense that it was different for each vehicle.

GM was pretty good about using the same stuff over many vehicle lines though, so perhaps they at least used all the same fitting sizes. Unlike Ford which changed the tube fitting sizes on practically every application of proportioning valve. Keeping you from just easily swapping one from an '89 pickup into a '69 Bronco.
That would be way too easy!

Paul

I agree, there are likely different calibrations for what on the outside seem like identical valves. I was hoping that someone on the forum would know what the original application was for the proportioning valve included in the disc brake kits. That way I could pick up a cheap rebuild kit and avoid completely removing the valve, all the lines, etc. It's common knowledge (at least I thought so!) that these kits use GM components. One of the above posts in this thread gave a source for a rebuild kit, which I ordered and am awaiting. I will update this thread if the fix works.

There also is the possibility that the rebuild kit doesn't work, and I will be looking for a replacement valve. I sure won't be going back to the vendor I bought it from for another. I'd prefer one from outside their supply chain so I don't end up with another leaky valve, which, it sounds, is likely. Someone suggested NAPA. Knowing the OEM application would be nice.

When the front brake pads, of unknown origin as they came with the kit, eventually wear out, I more than likely will go to my local parts store and ask for pads to fit a '76 Chevy pickup or something, hold them up to each other, and I'll eventually find a match. You don't happen to know what the original application(s) were on the brake pads, do ya?

Just thought I'd save some time, as there have been hundreds of these disc brake kits installed by members of this forum. I was surprised when I couldn't find a thread about this. With all those kits running around out there, I find it hard to believe no one has asked this before.

 

[72Sport]

I agree, there are likely different calibrations for what on the outside seem like identical valves. I was hoping that someone on the forum would know what the original application was for the proportioning valve included in the disc brake kits. That way I could pick up a cheap rebuild kit and avoid completely removing the valve, all the lines, etc. It's common knowledge (at least I thought so!) that these kits use GM components. One of the above posts in this thread gave a source for a rebuild kit, which I ordered and am awaiting. I will update this thread if the fix works.

There also is the possibility that the rebuild kit doesn't work, and I will be looking for a replacement valve. I sure won't be going back to the vendor I bought it from for another. I'd prefer one from outside their supply chain so I don't end up with another leaky valve, which, it sounds, is likely. Someone suggested NAPA. Knowing the OEM application would be nice.

The link gives the year, 1977 Bronco.

When the front brake pads, of unknown origin as they came with the kit, eventually wear out, I more than likely will go to my local parts store and ask for pads to fit a '76 Chevy pickup or something, hold them up to each other, and I'll eventually find a match. You don't happen to know what the original application(s) were on the brake pads, do ya?

1976 Chevy half ton is the magic number for pads. Easy to remember since 76 was the first year Broncos had disc brakes. Half ton Blazers, pickups and Suburbans had the pads that were used in most kits. If you use 1977 as a year for spindles you may get big bearing. 1976 is the year you want.

Just thought I'd save some time, as there have been hundreds of these disc brake kits installed by members of this forum. I was surprised when I couldn't find a thread about this. With all those kits running around out there, I find it hard to believe no one has asked this before.

The Napa link said it was for a 1977 Bronco. It also said it was not an exact fit. I can't believe they would list it for a 1977 if it caused a braking problem that would cause a liability problem.
It may be just fitting sizes for the brake lines or line length.