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centralizing brake pressure differential valve

 
  #16  
Old 06-09-2017, 03:57 PM
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Originally Posted by ultraranger View Post
You need to get one of these. Once you get the spool re-centered, insert this valve lock tool, before you start bleeding the brakes out, and the spool will be held in place so it can't shift off-center again.

https://www.musclecarresearch.com/brake-valve-tool
NICE! Thanks Steve.

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  #17  
Old 06-10-2017, 08:28 AM
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I used an extra trip grounding switch. I used JB weld epoxy to hold it in place. Worked for me a long with a nail hook made from a paper clip.
Orich

 
  #18  
Old 06-10-2017, 08:42 AM
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I have the valve lock tool from Muscle Car Research.



Valve lock tool shown installed into the centralized brake valve (finger tight only) just prior to bleeding the brakes out.



....although, it's not too difficult to take a 3/8"-24 Allen screw and turn the tip down on a lathe to make one, like I had done here (on the right). You just make the pin the same dimension as the pin sticking out of the bottom of the warning switch.

 
  #19  
Old 06-10-2017, 08:13 PM
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Originally Posted by hot-rod View Post

i try it yesterday 5 or 6 times... But the fu*** light wont go out Someone has an idea what I could still try??
Replace the brake pressure differential valve warning lamp switch, it's a notorious POS!

When it fails, the warning lamp on the dash comes on...and stays on.

C8AZ-2B264-A .. Brake Pressure Differential Valve Warning Lamp Switch / Obsolete ~ Available NOS & from auto parts stores.

1968/69 all FoMoCo Passenger Cars; 1968/79 F100/350, Bronco & Econoline.
 
  #20  
Old 06-10-2017, 09:32 PM
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Why just replace parts possibly unnecessarily, test it first with an ohm meter or self powered test light.
There is no need to guess at these things.
 
  #21  
Old 06-10-2017, 09:59 PM
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Originally Posted by mrpotatohead View Post
Why just replace parts possibly unnecessarily, test it first with an ohm meter or self powered test light.
There is no need to guess at these things.
Who the hell is guessing? I wouldn't tell people to replace this switch, unless I knew it was crap.

From 1968 thru 1997, I passed out 100's of these POS switches to Ford techs.
 
  #22  
Old 06-11-2017, 05:37 AM
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The switch is ok. I have tested it
 
  #23  
Old 06-11-2017, 08:38 AM
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I guess this one wasn't crap!
 
  #24  
Old 06-11-2017, 10:04 AM
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Originally Posted by mrpotatohead View Post
I guess this one wasn't crap!
My theory on this is that back in Bill's days of passing out parts, over time, he possibly passed out a lot of these switches because the customers (possibly even the Ford technicians themselves) were telling him they needed a new one because brake fluid was leaking from around it and they surmised from this that the switch must be bad.

If brake fluid is leaking out from around the threads on the (nylon) warning switch, it ain't the switch that's bad, since under normal circumstances, the switch is completely isolated from coming in contact with the brake system fluid/pressure.

If brake fluid is coming out from around (or through) the warning switch, the seal or seals on the pressure differential valve spool are the problem and not the switch itself. Just changing out the warning switch won't make the real problem go away. --it'll be back and soon.

You can see from this diagram where the pressure differential valve spool seals are in relation to the warning switch. No fluid should ever come in contact with the switch. If it does, the seals, not the switch, are the culprit.

 
  #25  
Old 06-11-2017, 10:27 AM
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Originally Posted by ultraranger View Post
I have the valve lock tool from Muscle Car Research.



Valve lock tool shown installed into the centralized brake valve (finger tight only) just prior to bleeding the brakes out.



....although, it's not too difficult to take a 3/8"-24 Allen screw and turn the tip down on a lathe to make one, like I had done here (on the right). You just make the pin the same dimension as the pin sticking out of the bottom of the warning switch.

i just went ahead and ordered the tool. I almost thought that a guy could use a bleeder screw from a wheel cylinder as it has a cone shape on the end and the threads match. Oh well. I don't feel like messing with it much more than one more time hahaha. Orich had a good idea but I don't have a spare switch. I'll report back when I get it working properly. Thanks for all your input guys
 
  #26  
Old 06-11-2017, 10:54 AM
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Originally Posted by KOT390 View Post
i just went ahead and ordered the tool. I almost thought that a guy could use a bleeder screw from a wheel cylinder as it has a cone shape on the end and the threads match. Oh well. I don't feel like messing with it much more than one more time hahaha. Orich had a good idea but I don't have a spare switch. I'll report back when I get it working properly. Thanks for all your input guys
The bleeder screw has the right diameter and thread pitch. The problem is the tip wouldn't pass through the small hole in the brake valve for the tip to come in contact with the valve spool and hold it in place --at least not without turning down the tip of the bleeder screw on a lathe.

The pin has to be able to pass through this small hole in the valve body, where the switch normally screws in.

 
  #27  
Old 06-11-2017, 12:00 PM
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Originally Posted by ultraranger View Post
The bleeder screw has the right diameter and thread pitch. The problem is the tip wouldn't pass through the small hole in the brake valve for the tip to come in contact with the valve spool and hold it in place --at least not without turning down the tip of the bleeder screw on a lathe.

The pin has to be able to pass through this small hole in the valve body, where the switch normally screws in.

aaahhhh yes. I didn't think about that. Glad I just ordered the tool. Thanks
 
  #28  
Old 06-11-2017, 01:55 PM
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Originally Posted by KOT390 View Post
aaahhhh yes. I didn't think about that. Glad I just ordered the tool. Thanks
$10.00 dollars for a 3/8"-24 screw may seem expensive but it's a worthwhile component to retain your sanity when bleeding the brakes out, to keep the spool centered and to keep the warning light from coming on while you're bleeding out the system.

With all the brake work I've done over the years, I wish I had had one of these way back in the beginning. I understand what the valve does and why, and how to recenter it but, it's still a pain to recenter the spool once it shifts. If you have something to keep the spool from shifting before hand, it just makes things a lot simpler when you're done servicing the brake system.
 
  #29  
Old 06-15-2017, 04:44 PM
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Happy to report that the tool worked great. Brakes are bled clean and in good working order and the light works properly with a new bezel from Macs Antique Auto. Thanks for the help all

KOT390
 
  #30  
Old 06-15-2017, 05:35 PM
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I solved my red light problem by cracking loose both lines on the master cylinder, letting a little fluid drip, then tightening the lines back up. Worked for me.
 
 
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