Disc brake control valve on 67....?

[WarrenC]

I was under my car today doing some cleanup and detailing and noticed a small cylinder shaped valve in the brake line near the rear end housing. I also noticed it was damp with brake fluid, so I looked it up in my Ford shop manual.
It's the disc brake control valve, which must be replaced as a unit, no repair or adjustment, etc...., so I went to my handy NPD catalog to see what one would cost and found nothing.
I finally found a proportioning valve that has the right part number, but it says replacement, brake line mod required, fits on the front apron. It's an adjustable proportioning valve. So I assume I have to eliminate the one by the rear axle and install something like this? What does the one in the rear brake line do?

I'm a little confused here, any insight would be appreciated!

 

[mfp4073]

Ok, you are unique! Most of us have added disks. What you are talking about is the valve that proportions pressure between the rears and fronts. Was only on disk brake cars. Probably pretty expensive to replace. An option is replacing it with an adjustable unit from wilwood or similar manufacturer. The old one will have to be patched (replacement with a jumper or something) and then then adjustable added somewhere between the proportioning block and the rear brakes. Here is my setup which was a disk brake conversion, but will give you some ideas.

I was under my car today doing some cleanup and detailing and noticed a small cylinder shaped valve in the brake line near the rear end housing. I also noticed it was damp with brake fluid, so I looked it up in my Ford shop manual.
It's the disc brake control valve, which must be replaced as a unit, no repair or adjustment, etc...., so I went to my handy NPD catalog to see what one would cost and found nothing.
I finally found a proportioning valve that has the right part number, but it says replacement, brake line mod required, fits on the front apron. It's an adjustable proportioning valve. So I assume I have to eliminate the one by the rear axle and install something like this? What does the one in the rear brake line do?

I'm a little confused here, any insight would be appreciated!

 

[Edbert]

Hmmm...something not quite right here, but I am not sure what.

The last 5 1967s I've owned were equipped with factory PDBs. I am not familiar with a cylindrical valve on the rear axle. The proportion valve is mounted exaclty like MFP has in his picture (the part he wrote "R/FR/FL" on), this part was different in disc brake versus drum brake cars and possibley in power disc brake cars as well. But externally there is no difference. There is a brass valve on the rear axle but it is a distribution valve from the single line feeding the rears, and it is sort of squared off and "blocky" not cylindrical.

I see you have a 9-inch rear and in your car with a 289. This is very uncommon in 67s, and unless you have a K-code engine it has been added by a previous owner. If that is the case then I'm going to say the cylinder is not stock. Can you take any pictures of it for us?

 

[mfp4073]

I may be wrong (as pointed out)...I had thought they used a rear proportioning valve. Pics would be great!

 

[ron67fb]

I'd like to see the picture from the shop manual.

 

[WarrenC]

I'll try to get a picture of it tomorrow evening, maybe tonight if things work out. It's been one of those days. I've been kicking myself all day for not taking a picture of it when I had it jacked up yesterday!
By the way, my signature is wrong-it's not a 9" rear end, it's an 8". If anybody has a Ford shop manual handy, you can see it in one of the diagrams (I think it's figure 21) in the brake section. And they call it a disc brake control valve.
I'm sure all my brake lines are stock, and I've never seen a proportioning valve in the engine compartment. I have the equalization valve that triggers the brake light if there is a pressure differential between front and rear, but that's it. I'll try to scan a picture of the Ford manual here in awhile.
Thanks for the help, by the way!!

 

[Edbert]

The block on the rear axle can act as a primitive proportion valve I guess. It is not adjustable at all though (like the one in the picture), it also is the distribution block for the two rear wheels. One line goes in and two come out. But a proportion valve is usually required when you convert to rear discs since they'll lock up too easilly, with drums in the rear they are not needed, right?

 

[WarrenC]

OK, well here's a scan of the Ford manual diagram. I cropped it so it's right in the middle of the drawing and it's called a disc brake control valve. Anybody who knows what this thing does, PLEASE let me know! And then tell me why I can't find one in any of my catalogs.

 

[WarrenC]

So...., nobody has any knowledge of this thing?

 

[mfp4073]

Thats what I thought I was talking about....

 

[WarrenC]

You're right MFP, that was what you were talking about. I guess I was hoping someone could lead me to a way to not modify everything to get it to work. I find it hard to believe nobody makes a replacement for this part. I'd also like to know what it does exactly. I mean, what is it we are trying to accomplish with a proportioning valve. Do we need to decrease pressure to the rear drum brakes? That's the only thing I can think of that this thing would do.
So if I took it out and made it a solid line to both rear brakes, would I be constantly locking up my rear brakes?

 

[mfp4073]

You're right MFP, that was what you were talking about. I guess I was hoping someone could lead me to a way to not modify everything to get it to work. I find it hard to believe nobody makes a replacement for this part. I'd also like to know what it does exactly. I mean, what is it we are trying to accomplish with a proportioning valve. Do we need to decrease pressure to the rear drum brakes? That's the only thing I can think of that this thing would do.
So if I took it out and made it a solid line to both rear brakes, would I be constantly locking up my rear brakes?

I am feeling stupid cause I cannot remember if its less or more pressure for drums or disks. but without it you will lock one of em up before the other. I guess it would have to decrese pressure to the drums when you think about it. The adjustable replacement I showed was just an option to get out of trying to track down an original. I have no idea if they are available or how much you would spend. I know the adjustable model will get the end result. You can put it anywhere along the line.

 

[ron67fb]

You want less on the rear. Get an aftermarket unit, and do as you wish to that factory valve. I'd just try to re-tighten it and see if it stops leaking.

 

[67FBSCODE]

That style was only used for a couple of years. My 67 has it, it is a proportioning valve like every disc/drum brake car has. Most are mounted up front and also act as a distribution block. You can mount the one you have anywhere in the rear brake line, it does not have to be on the rear end. I think 68s moved on to the more traditional style. john

 

[WarrenC]

OK, I talked to my favorite brake parts and service shop today. I couldn't get the valve in question off easily (rust and time) but I took pictures and they were puzzled. They said the valve in the front (pressure differential valve with brake warning light switch) is the proportioning valve. They figured this was a residual pressure valve (like the wilwood kind they sell), but they weren't sure. They told me to take it off carefully and bring it down or talk to a nearby Mustang shop (The Mustang Ranch) and figure out what it was. They even called an old Ford parts guy they knew who didn't recall anything like that. I called The Mustang Ranch and decided they are genuine ..., well you can guess. I've talked to this guy twice, and both times he has been rude and no help at all. He told me to bring it to him, he'd fix it but he doesn't fix car's on the phone. He's only about 40 miles away and only open when I'm working. Perfect.
The brake shop said it could not be a proportioning valve because it only deals with the rear brake line, which seems to make sense, right?

 

[67FBSCODE]

On 67 only the front piece is a distribution block with light switch. The rear piece is the Rear Brake Proportioning Valve #c7oa-2b091-c. Does it look like this.

 

[WarrenC]

Yep, that's the one. So what do I need to do with this thing? I can't find a new one, so what are my options? It can't be rebuilt as far as I know and I have a feeling even if I get it to stop leaking it's not doing it's job.
Would the Wilwood residual pressure valve do the job?

 

[67FBSCODE]

I think I would look into one of the adjustable units. One line in one line out. Then you can set it the way you like it. John

 

[mfp4073]

hehe, I feel better, I hate when I think I know what I am sayin, but everyone else says no! I did some research on these when I was looking to convert my car to a factory disk brake setup. There seemed to be a lot of speculation at the time as to whether there was proportioning or distribution in the block with the brake warning light. I dont know if it would work, but at one point I was told I could use one off a modern 50 disk/drum car. Of course I never actually found one on a car. It was due to this and at the time the price of those original parts. I have no idea where I found a price and such, but it seemed like $120. When I looked at the adjustable ones that you had the ability to "tune" the brakes on your car and get it for only $50, I immediatly abandon the idea of doing something original. If its leaking there is something soft in there that has gone bad (or its come loose). If we can put a man on the moon we MUST be able to repaired somehow.

 

[WarrenC]

Yes, it seems your original post was right on the money. I just didn't want to accept it at first, but I'm beginnig to think it's the easiest way out. I'll just have to have a piece of line made to take up the slack in the back brake line and put it somewhere accessable. Kind of a pain to adjust where it is......
It seems odd that they would have chose to put it where they did.