What is this block? (Brakes)

[swood]

What exactly is the function of the block that the brake lines run through that attaches to the frame. This is on the top of the frame rail below the master cylinder where the lines run through. Looks sort of like an H block, is this a proportioning valve of some sort? I'm switching over to 4 wheel discs and need to figure this stuff out soon.<br><br>Thanks.

 

[kuch68]

I don't know as much as the experts around here. But I am pretty sure that it is not a proportioning valve. It is just a pressure differential valve that is monitored by the little red light next to your ignition switch on the dash. All it does is if the pressure blows out in one side of the lines then a shaft translates inside of it towards the blown out line because of the loss of pressure. This is how it senses the blow out. Then it should light up the light on the dash. But most won't because they haven't been maintained.<br><br>Josh<br>75 Bronco<br>http://www.geocities.com/broncokuch/<br>

 

[lars]

Josh described it right.<br><br>Depending on what 4 wheel disc brake setup you install and what you have on your EB (hard top or soft top, spare in back, etc) you may not need a proportioning valve. If you do, don't bother with the Ford OEM unit. Get a Wilwood adjustable valve instead and install it in the rear circuit between your master cylinder and H-block. Even if your brake idiot light doesn't work, the H-block is a handy junction for tying brake lines together.

 

[Guest]

its a pressuer differential metering block. it will work for your 4 wheel disc. it helps split the pressure correctly

 

[eBronc]

It's really more of a junction block than a proportioning valve.<br><br> It serves to connect all the lines together and has a brass piston with seals and springs on both ends and is tapered in the middle. When brake pressure is the same on both sides of the piston (front and rear brakes), the pin for the brake warning light switch is centered in the taper, and the light is out. When pressure is unequal (usually because of a leak in a wheel cylinder), the piston moves slightly in it's bore and pushes on the pin for the brake warning light switch, which lights the light (unless the bulb is out). If you need to disconnect the old lines, use a tubing wrench, plenty of penetrant, and maybe a little heat from a propane torch.<br><br>If you add front discs (or 4 wheel discs), install a Wilwood proportioning valve in to the line the the rear brakes so you can adjust the bias front to rear.<br><br>I had this setup in my '88 5.0 Mustang that I installed rear discs on and autocrossed, and it's VERY handy for setting up your brakes just the way you like 'em. I liked it so much I did the same thing on my '66 Porsche 912 project, and my current '70 eBronc project truck.

 

[chuck]

The deferential valve is exactly that. The front and rear brake fluid never comes togather. There in no <br>blocking or regulating or anything else. The sole function of the deferntial valve is to make a light <br>come on, on the dash. Nothing else other than a convenient place to connect the lines.<br>