Ford Muscle Cars Tech Forum banner

1 - 14 of 14 Posts

·
Premium Member
Joined
·
8 Posts
Discussion Starter #1
I've got a '68 Montego MX with non powered drums all the way around. I just recently replaced all the drums, wheel cylinders and brakes. Once I was done I power bled the whole system and then tried what the shop manual said to do to get the valve re-centered. I still couldn't get it to center so I asked a guy I work with (used to work in a Ford garage years ago) what he suggested. I tried that also and it still wouldn't center. When I got the car I found the sensor was unplugged so I don't know how long the valve has been that way. Does anyone have any suggestions or is it possible that it may be seized up and needs replaced? My next question would be if it needs replaced are these still able to found or are they obsolete? I've done a little looking and they don't seem to be plentiful if any at all. I've pulled some numbers off of it but I'm not really finding anything matching the number. The number I believe that's on it is C8OA 2B257-K. Is this an actual part number? If it is, is it still available or is there a replacement. Thanks in advance, this site has been a wealth of info.

Todd
 

·
Registered
Joined
·
9,251 Posts
Take the valve out of the system, take it apart and clean it. After verifying the shutoff valve moves in the bore, the make a tool from a spare brake fitting that screws into the switch port and the butt end of a 1/8 drill bit. Center the valve manually, screw in the fitting, slide in the drill bit to seat in the valve then glue the bit in place in the fitting. Re-install the valve and bleed the system. Remove the tool and install the switch and harness.

Nest time you bleed or work on the system, remove the switch first and install the tool to hold the valve in place.

You can check with Master Power or Stainless Steel to see if there are replacement valves, otherwise you'll have to source one from a similar scrapped car.
 

·
Premium Member
Joined
·
8 Posts
Discussion Starter #3
ckelly, thanks for the quick reply and tip. I pulled the proportioning valve off and the bore is slid to the rear. It does not move freely and since it is drums all the way around it doesn't have the bleeder on the back side to have access to push the bore through. Any suggestions on getting the bore to move freely it appears to be seized up.

Thanks again

Todd
 

·
Premium Member
Joined
·
1,479 Posts
I'm not a brake expert but why does it even need a proportioning valve if it's four wheel drum brakes? I thought they were only needed for mixed brakes (disc/drum). I now have four wheel discs and I do have one but I can adjust it from one extreme to another and can feel no difference either way.

John
 

·
Premium Member
Joined
·
8 Posts
Discussion Starter #6
It's not really necessary. It's my understanding they started putting this in when they started going with the brake sensor. It's just there to shutdown fluid to the system that has the problem and trip the sensor so the light comes on.
 

·
Registered
Joined
·
10,299 Posts
I'm not a brake expert but why does it even need a proportioning valve if it's four wheel drum brakes? I thought they were only needed for mixed brakes (disc/drum). I now have four wheel discs and I do have one but I can adjust it from one extreme to another and can feel no difference either way.

John
Here's how to see why you have one. Go to a large empty parking lot, get it up to 20+ mph, make a slight turn and stomp on the brakes. Normally, there should be even braking and stop with a bit of sliding to the side. If yours fishtails and tries to spin-out, you need to adjust your proportioning valve, or in slippery conditions (damp/dusty/gravel/etc.) you'll get a nasty surprise even going straight. :eek: I like to test on pavement driving straight ahead with an observer or video to see if the rears lock-up before the fronts and adjust until the fronts lock just before the rears. This way, the car remains more stable and even in an evasive maneuver will plow straight or show under-steer with less likelihood of spin-out.

This testing holds more importance to me since the day I was driving my 4-drum car that had the valve removed (I was 21 and too lazy to re-plumb it in after adding a Line-Lok), had to hit the brakes hard one day, and nearly had a head-on collision with the car that was following me. The car spun so fast my left elbow hurt for a few hours from being thrown against the door.

FWIW,
David
 

·
Premium Member
Joined
·
1,479 Posts
I have to admit that I've never really stomped on the brakes trying to make them lock, but I have got on them pretty hard and couldn't fell any difference with the valve set fully proportioned to the front or the rear brakes. Maybe I should. I was always under the assumption that it was a drum/disc thing because they need different pressures to operate properly.

Thanks,

John
 

·
Registered
Joined
·
10,299 Posts
Not my point - if you have a prop valve do NOT remove it or defeat it. If you have upgraded your brakes, you probably need one. If you changed tires sizes or stagger you may need one to take advantage of better rear traction. This is standard in road racing and other sports where controlled braking is a necessity. Now, if your car did NOT have one, then it is proportioned by other means, such as smaller rear brake rotors/drums, shoes/pads, smaller wheel calipers/cylinders, or other such 'auto-proportioning' methods.

Point is, there is proportioning necessary in any car due to available traction, suspension reaction, mass shift, etc. Pay attention to how it is done with your car, and how it may need re-balancing (especially if modified), so you can avoid some nasty surprises.

David
 

·
Premium Member
Joined
·
8 Posts
Discussion Starter #13
Thanks again to everyone who replied. I went to one of the local junk yards here and found one on a Torino that was the same style. Got everything hooked up and bled and the light went bye bye.

Todd
 

·
Premium Member
Joined
·
5,564 Posts
hey now, that was a pretty satisfying thread to read.
 
1 - 14 of 14 Posts
Top