67 Brake Proportioning Valve & Distribution Block, can you adjust it? Mine is stuck to one side and causing the brakes to work unevenly and brake warning light stays on.
Nothing can be adjusted on an OEM set-up but the light can be reset. The reset directions are in the factory shop manual and this little tool can be helpful.
Bear in mind the brake proportioning valve has nothing to do with the brake warning lamp in the dash. The brake proportioning valve meters fluid going to the rear brakes. It opens when the pedal is released allowing the fluid to have unimpeded flow back to the reservoir from the rear brakes. It could be stuck open or closed and still would have zero effect on the idiot lamp.
In all but the last 1967’s built the brake proportioning valve (used only on disc brake equipped cars) is mounted just forward of the rear axle to the floor pan.
Very late 1967 Cougars were supposedly set up like a 1968 with the proportioning valve mounted outboard of the distribution block on the inner fender but I have personally never seen a 1967 Cougar like that.
“Very late 1967 Cougars were supposedly set up like a 1968 with the proportioning valve mounted outboard of the distribution block on the inner fender but I have personally never seen a 1967 Cougar like that.”
Nor I and I have seen some VERY late 67’s in my time. Does the MPC show any evidence of that having occurred? Sorry to sidetrack the thread…
After looking at the Master Parts Catalog for the past hour I have to say no.
It shows P/N C7ZZ 2B257-D for 1967 and C8ZZ 2B257-B for 1968. No mention of any early introduction for the 1968 system. Normally if there is a mid model year change there is a implementation date in the MPC because of the effect on line assembly.
My copy of the MPC is a April 1969 issue date. It had a few revisions done to it so occasionally there will be some 1970 information but not here.
BTW 2B257 is the distribution block.
The Proportioning valve is 2B091. For 1967 - 69 all cars used C70Z 2B091-B
The distribution block for 1967 is different than the one for 1968 - 69 because of the extra two ports for the proportioning valve in the later style unit.
For some reason the casting number changed each year 67, 68 and 69 brake valve. I see no physical changes inside or out.
https://secure.cougarpartscatalog.com/c9oa-2b091-a.html?attribs=87
Thanks Don, will you tell me what the book says concerning resetting the light?
In short… Have someone inside the car pump and hold the pedal while you crack the line at the block. The rush of fluid will move the piston, the cutaway picture on my site will help you visualize the process.
Thanks, I will bleed it.
Also a further note: The valve found at the left rear side of the floorboard on the 67 and mounted on the distribution block on the 68-up cars is not a proportioning valve at all. It’s a check valve. It simply holds pressure in the line after the pedal is released. If I remember correctly it’s 10LB.
-Keith
Is it fair to say it proportions the pressure? The other part only distributes fluid. A check valve is a gate and let’s no portion of the fluid get by it like the vacuum check valve in our boosters
False. It is actually a proportioning valve. It provides metered flow through an orifice to the rear brakes. It provides unrestricted flow for fluid returning to the master cylinder.
Just like any other proportioning valve.
The valve retains 10 PSI. Period.
I haven’t had a reason to care about this function yet but I’ll be doing mine so I’ll have to do my own checking,there’s obviously a difference of opinion but it doesn’t seem to make sense that a hydraulic brake line system would hold any pressure?
The only valve in a hydraulic brake system that hold pressure is a residual valve. A residual valve is used in cars or trucks when the master cylinder is mounted low in the vehicle, like below the floor boards. We installed a residual valve in the brake line to the rear brakes and another in the line to the front brakes in my Uncles 50 Ford pickup. We retrofit in a dual master cylinder below the drivers side floor board. Drum brakes require a 10 PSI rated valve, disk brakes use a 2 PSI version. Without a residual valve in the lines to the brake fluid would drain back and overflow the low mounted master cylinder.
You are very confused.
Exactly right. It doesn’t retain any pressure. The proportioning valve allows free flow back to the master cylinder while restricting flow when the rear brakes are applied.
Just to add a little more confusion to this thread… I thought it was the residual valve in the master cylinder that kept a small amount of pressure in the line. Reason being, if the umbrella seals relax in a wheel cylinder they leak. No residual pressure in a caliper as it would create drag. Pretty sure I am correct about this. Anyone?
True. Master cylinders incorporate a residual valve in the case of drum brakes. This is not to be confused with the proportioning valve. In the case of our Cougars there is a residual valve in each half of the master cylinder if the car has four wheel drum brakes.