I removed the pressure differential valve and proportioning valve yesterday. The rubber ring in the groove around the proportioning valve just fell apart. After cleaning the proportioning valve the rubber ring looks like it just covers two small relief ports in the groove. I put a O-ring back in the groove, is this okay or should I make a rubber ring with the square corners like the original.
Also the valve piston in the pressure differential valve, it's in the correct position, I tried to push it with a punch, I couldn't get it to move, is the piston hard to move or do you think it's stuck in the bore? According to the Ford maint. manual the piston has 3 o-rings on it.
Kenny
You can use a air gun to blow the piston out, just be carefull not to lose any of the bits inside as they will exit out rather quickly.
Cobra Automotive sell the kits for those Valve's. Part Number 100-1679 $.
I removed the pressure differential valve and proportioning valve yesterday. The rubber ring in the groove around the proportioning valve just fell apart. After cleaning the proportioning valve the rubber ring looks like it just covers two small relief ports in the groove. I put a O-ring back in the groove, is this okay or should I make a rubber ring with the square corners like the original.
Also the valve piston in the pressure differential valve, it's in the correct position, I tried to push it with a punch, I couldn't get it to move, is the piston hard to move or do you think it's stuck in the bore? According to the Ford maint. manual the piston has 3 o-rings on it.
Kenny
I have used a o-ring like you just did before and haven't noticed any problems. I have a Pro valve that is clogged that came off my 69 CJ car years ago-replaced it with one off a SCJ drag car I had for 'parts". how do I go by disassembling this piece? I don't want to ruin the outer surface. Its been setting in a drawer for 15 years now. Gary
I'm going to order the rebuild kit, from Cobra Automotive tomorrow if I remember. I'll post the price and rebuild instructions when I receive them.
Gary I know you've repositioned the piston in the pressure differential valve before. How much force does it take to move the piston? I pushed on my piston with a punch and was unable to move it. I'm woundering if it's stuck on it takes more force to reposition the piston.
Kenny
I'm going to order the rebuild kit, from Cobra Automotive tomorrow if I remember. I'll post the price and rebuild instructions when I receive them.
Gary I know you've repositioned the piston in the pressure differential valve before. How much force does it take to move the piston? I pushed on my piston with a punch and was unable to move it. I'm wondering if it's stuck on it takes more force to reposition the piston.
Kenny
Are you referring to the metering block piston that the brake light switch reacts to? If so, then I had to move them one way and that was away from the hex cap hole in the one end. I would use a short dowel that moved the piston towards the front of the car and used the brass hex bolt to move the piston until it was centered.Now on my 1968 Shelby,well.. its the OTHER way and I moved it some by using a scriber and moving it "over" to the rear of the car. I tried the air method but with my metering block off the car and trying to plug the line holes it didn't work. I believe that when you lose the front brakes that piston moves towards the rear of the car and when you lose the backs it moves to the front of the car. NOW if you know what brakes you lost when the light came on then you can manipulate that piston. I lost my rear brakes back in 95 on my 1970 GT350. I took it out for a spring run. My brakes were not right BUT I have driven and stopped bad brakes before in 4 speed cars. Well by the time I got to the gas station a mile from my house my brake light went on. Got home and inspected. Lost a RR cylinder. Replaced. Bled. Light still on. Well started bleeding the fronts until the light went off. It worked Now Ken, is yours still on the car connected? Did you get your light on due to the rear end work and line/cylinder replacement? If so you might want to try what I did to center the piston then.Here is a picture of my valve and piston for my 1968. Are we on the same page? You are saying pressure differential valve. That may be the correct name BUT I am used to this pic below being a metering block and the round brass thing above being a proportioning valve as you stated. If you want. I can take my spare metering block and play with it to find the best way to center the piston when its moved to the front. When moved to the back is easy as stated above. Does anyone have a brake switch that mounts to this block. mines toast(spring is bad ). I am thinking that I really do not need a brake light to tell me when my brakes are out anyways so I can just shave the pin off and have it for looks if I cannot find one. While I am typing, anyone need seat belt spacers? I am making them up.
Yes were on the same page, pressure differential valve is what the Ford maint. manual calls the metering block. I haven't had any problems with the brake light coming on, while I'm doing a total rebuild on the brakes. I removed my metering block and proportioning valve so they could be cleaned up and make sure their working properly. I tried moving the piston in the metering block by pushing it with a punch. I wasn't able to move the piston so I'm wondering is the piston stuck or should it be very hard to move.
I bought the rebuild kit for the proportioning valve today from Cobra Automotive the kit is $28 the 67-69 proportioning valve doesn't come with rebuild instructions, so he sent me a copy of the instructions for the 65-66 proportioning valve. Hopefully they will help.
How are you taking the proportioning valve apart without damaging it. I have a spare metering block and proportioning valve. The block was off a SCJ drag car and the proportioning valve off my last CJ mach. didn't use it because we found out it was clogged when the back brakes wouldn't bleed. Bought that car as a roller with a new drivetrain so wasn't aware of the pro valve being stuck. The previous owner bought the car running with a cleveland in it and it was off the road for at least 10 years before I worked on the brakes. I would like to restore that valve and sell the complete setup. If I can take it apart without damaging the brass I will. Does the rebuild kit come with the "square" O-ring? Gary
Feb 05, 2008 04:07
68GT350 Guest
Hey guys i am trying to post a reply but i get a denied message saying are you a bot. What am i doin wrong ?
Hey guys i am trying to post a reply but i get a denied message saying are you a bot. What am i doin wrong ?
Not sure what you mean since I see you post right here. What else are you trying to do since you did post a response right above
Feb 05, 2008 18:49
68GT350 Guest
I can do a "quick reply" but i cannot use the "post reply". i was going to post some pics of a disasembled proportioning valve. Everytime i hit the post reply it comes up with a denied message. which is a bit stange because a posted a message on this thead yesterday.
This is the proportioning valve rebuild kit from Cobra Automotive. It doesn't come with the square cornered rubber ring that's originally on the outside of the proportioning valve, instead it came with an 0-ring.
Kenny
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
Now Ken, is yours still on the car connected? Did you get your light on due to the rear end work and line/cylinder replacement? If so you might want to try what I did to center the piston then.Here is a picture of my valve and piston for my 1968. Are we on the same page? You are saying pressure differential valve. That may be the correct name BUT I am used to this pic below being a metering block and the round brass thing above being a proportioning valve as you stated. If you want. I can take my spare metering block and play with it to find the best way to center the piston when its moved to the front. When moved to the back is easy as stated above. Does anyone have a brake switch that mounts to this block. mines toast(spring is bad ). I am thinking that I really do not need a brake light to tell me when my brakes are out anyways so I can just shave the pin off and have it for looks if I cannot find one. While I am typing, anyone need seat belt spacers? I am making them up.
