While restoring my '71 Malibu into a Pro Touring car, the main front to rear brake line was installed today. The car is also being converted to 4-wheel BAER disc brakes and a knob adjustable proportioning valve will be installed into the front line at a later date. My question centers around the stock, factory installed junction block where the lines coming down from the master cylinder join the front & rear feeder lines. Can anyone tell me for sure what function this block performs? Does it balance fluid flow? Or simply act as a junction for lines? I know about the electrical wire that hooks to it, and senses an imbalance in fluid movement, illuminating the "BRAKE" light on the dash. I'm asking because it sure would be a whole lot easier to use this factory block, joining my new brake lines to it using the stock configuration, rather than fabricating jumper lines. I seem to recall BAER saying it couldn't be used with their brakes, but I wanted to check here on TC for anyone who might have some 1st hand experience.

First off, I need to question something you said... "and a knob adjustable proportioning valve will be installed into the front line at a later date." Why at a later date and why in the front line? Any adjustable valves should be placed in the rear line! You don't need to limit the front brakes pressure, only the rear!

Ok, now on to your question about the stock valve. In 71, a factory disk/drum car should have what is called a combo valve. It is called that because it does several things at once. First, it acts as a distribution block to split the front brake lines. Next, it gives us the factory brake warning light hookup. Next, it has a small residual pressure valve in it to keep pressure on the rear drums. Next, it act as a delay valve for the front brakes until the rear brakes start to work. Finally, it also limits the amount to pressure that can be applied to the rear brakes.

If you don't care about the brake warning light, then my advise would be to replace the factory unit with just a single, adjustable valve in the rear line. That way, you can fine-tune the brakes to your car.

Good luck,
Bill C.

Bill-

You're correct, I mis-stated the location of the BAER valve...it would be for the rear line. This stuff isn't going to be installed for some time now, as the body is seperated from the chassis right now. Sounds like that block has enough functions that BAER's advice to not use it makes sense. Thanks for making sense of the stock junction block!

Just lose the block altogther. All you need from the master cylinder to the brakes are;

-For the front you can just go straight from the MC.
-For the back lines you need the adjustable pressure valve and a 10psi residual valve for rear drums.

However I remeber reading somehwere that you may need a 3psi residual valve for disks. Maybe Bill can shed some more light this.

Think that's it.

Later
Steve

Wana,
There should be no residual pressure valve for the disk brakes, even for the rears I'm told. The disks retract by themsleves, but only to the point of not having any real pressure, but will still barely touch and rub the rotor. This is normal. Any residual pressure in the lines will keep the pads against the rotors both heating the rotors really quick and wearing the pads really fast.

If you have rear drums, you really should use a residual pressure valve and the 10lb one should work fine tho I've heard of people even using the 2 lb ones.

Good luck,
Bill C.

Just got an e-mail from BAER, they said there would be no problem using the stock junction block. Apparently, there is no fluid restriction performed by the block. Thanks for your input guys! graemlins/thumbsup.gif