i read on here the function of this valve but can't find it now...i did the disc swap on the front and didn't use this valve. i hear it is for the light and some say it is for the pressure diff. from drum to disc... i am looking at putting disc on the back of my '73 grabber... any help would be nice...frank...
I have never changed that valve in any disc conversions I have done. It does turn on the brake light on the dash should one side of the brake system loose pressure. What I've always suggested is go to an empty mall parking lot on a rainny night and get some speed up and lock your brakes. You will know real quick if you need a proportioning valve. If the back tries to pass the front, you need one. But its much easier to buy an adjustable one from Summit or Ford Motorsports and install it. It just splices in series on the single line that goes to the rear. Much easier than changing all the brake lines and valve under the hood. I have never needed one myself.
dennis, that is what "confusses" me. if it just turns on the light then why is it adj. ... is the back or front suppose to brake first?...frank...
The back is suppose to brake first. If the front were to brake first and you were to apply the brakes on a wet road going around a curve you might very likely find yourself going the other way.
"thanks...i needed that". i just went to jeg's and they list them from...$39.50-$114. is one better than the another ? ...frank...
I just did front swap on my 73 and I will use on off a Granada. Dont discs need to have a small amout of preassure on them at all times? Anyway I just figure to use the factory set up as it was desinged.For four wheel disc I would use the adj. valve.What rear disc. set up are you using?
When I put disc on my 73 Comet, I just swapped them off of my 74 Comet including the valve. The 74 Comet now has drum all around. I did the swap cuz the first time at the track, it took forever to stop. A lot better with disc up front.... I don't know if I needed to swap the valve or not, but what the heck....I had it, so I did it.
the valve is supposed to limit initial pressure spike to the rear brakes. When you first hit the pedal, fluid movement presses a valve inside the prop valve to one side, which limits initial pressure to the rear, which keeps the rear from locking up. Ever put a valve on backwards? I did....and I know that they work for the REAR not the front. Also, try locking up the park brake while you're driving. It becomes a handful to try to stop it without fishtailing. That's why the proportioning valve is there so that when you hit the pedal, it won't chase you around. That being said, adjustable ones are set up more for 4 wheel disc conversions. If you're just upgrading to discs on the front, you probably won't need an adjustable valve. I remember not too long ago when I was racing the '75, still had 4 wheel drums all the way around. It stopped better than the '74 did with disc/drum setup. Another thing to consider about 4 wheel drums is you can adjust them for nearly zero drag, that and drums self-energize, which can make staging against the converter a lot easier. But, the downside...you only get one shot at slowing the car down. Once drums get hot they fade and you lose effectiveness. That's a bad thing on the street. I know when I put 4 wheel discs on the bracket car it made a world of difference. Now, I just put steady pressure on the pedal and the hotter they get the harder they grab. I have to remove pressure from the pedal to keep them from locking up sometimes. They're good pads, though (PF) on both front and rear, and no bias valve. I figured with 14x32 rear tires, I was not too concerned about locking up the rear.
The factory valve in your car turns on the light. The adjustable one you install, goes on the line brake line to the rear brakes. IT will have nothing to do with the light. The idea is to NOT let the rear brakes lock up before the front. If they do, you will have no control of your car. THe aftermarket valve once installed, will limit pressure to the rear brakes. As mavman said, go to the wet parking lot and lock up your parking brake. Then you will know.
Go to this web site and read their tech.Even though its geared for people building street rods,they have the same basic problems when they are designing the brake system.What ever you do,remember brakes are a safety issue,so don't do anything that is not first class.All of our work on these cars can be lost in a second,if we are lucky only car damage,unlucky, loss of life. www.ecihotrodbrakes.com/brake_facts.html Its not rocket science,but it does require planning and good parts and workmanship. Good luck.
Your'e very welcome,I have been dealing with the same issues on my Maverick.When I get mine all done,I'll post some pictures,and follow up with a list of what I did.I redesigned the system from the pedal out,with the goal of having a power setup tucked back in next to the firewall coming straight out,instead of on an angle,like the factory did.I've got it all mocked up,using a 1993 Ford Aerostar master cylinder with the original Maverick booster.I'm also using the Aerostar proportioning valve since it was disc/front and drum/rear.If I get the time this week,I'm stopping by hose shop to have stainless steel braided hoses fabricated from the master cylinder to the proportioning valve.I wasted $39.00 on trying to bend and flare the tubing and just couldn't get the fit and look I want.Bending tubing is an art,and there must be some voodoo magic involved in making perfect flares too.If a Snap-On flaring tool can't do them right,I give up.Can't possibly be me and my skills.Must be the tool.
