Brake Line Distribution Block / Switch
Thread Starter
Le Mans Master
Joined: Jul 2004
Posts: 6,248
Likes: 4
From: Lancaster PA
Brake Line Distribution Block / Switch
Could someone educate me on how a "brake line distribution block/ switch" works ? The theory on how it works What's inside ? are they repairable / How do you troubleshoot ? Where does the wire go to ? What does the electrical part do ?
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
Each input "side" of the block is connected to the outputs of the Master Cylinder and the block outputs are connected to each "system"(front and rear). There is a "slide" inside that needs to be centered in order for the fluid to flow to each "system" (front and rear) and keep the Brake light switch/lamp off. The switch is off when the "slide" is centered and on when off center. If one of the systems springs a leak, then the pressure from the OTHER system pushes the slide toward the failing side, BLOCKING THE FLUID from going to that side, turning the switch on which causes the Brake light to come on.
Thread Starter
Le Mans Master
Joined: Jul 2004
Posts: 6,248
Likes: 4
From: Lancaster PA
Each input "side" of the block is connected to the outputs of the Master Cylinder and the block outputs are connected to each "system"(front and rear). There is a "slide" inside that needs to be centered in order for the fluid to flow to each "system" (front and rear) and keep the Brake light switch/lamp off. The switch is off when the "slide" is centered and on when off center. If one of the systems springs a leak, then the pressure from the OTHER system pushes the slide toward the failing side, BLOCKING THE FLUID from going to that side, turning the switch on which causes the Brake light to come on.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Each input "side" of the block is connected to the outputs of the Master Cylinder and the block outputs are connected to each "system"(front and rear). There is a "slide" inside that needs to be centered in order for the fluid to flow to each "system" (front and rear) and keep the Brake light switch/lamp off. The switch is off when the "slide" is centered and on when off center. If one of the systems springs a leak, then the pressure from the OTHER system pushes the slide toward the failing side, BLOCKING THE FLUID from going to that side, turning the switch on which causes the Brake light to come on.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
My 75 has distribution/switch block that operates this way. Proportioning valves typically operate as pws 69 states.Burnt 71, you can unplug the wire from your switch to see if it is causing the light to come on. The parking brake lever has a switch that operates the same light.
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Race Director
Joined: Apr 2000
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
So it doesn't block any fluid from the failed side as some kind of safety device leaving you with the unfailed front or backs to stop you ? It just gives you a warning light as your foot on the brake travels to the floorboards and your Vette hits a parked Brinks truck. Brilliant ! and they wonder why they went bankrupt ? 
Last edited by MotorHead; Sep 25, 2009 at 05:25 PM.
Le Mans Master
Joined: Mar 2001
Posts: 6,640
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From: Ann Arbor Michigan
Race Director
Joined: Apr 2000
Posts: 17,672
Likes: 199
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
