astroboy

iTrader: (18)

I am going to be putting new lines on my car (90 chassis and bmc/booster) and wanted to make sure I was grasping the BMC operation correctly...mainly the line that comes out of the bottom of the proportioning valve that goes into the side of the bmc (on the front) and then comes out the top (also on the front) and goes to the dr side caliper.

If I am understanding it correctly the fluid is going to a secondary piston inside the bore that is supplying pressure for the dr side caliper. Is that accurate? Here is an illustration I found on the interweb that kinda illustrates it:



If I am wrong somebody please enlighten me. Thanks!

crashnscar

iTrader: (9)

It doesn't come out of the bottom of the prop valve, it goes INTO the bottom of the prop valve and then straight out the top and over to your passenger front brake. It is simply the reference pressure that the prop valve uses for front/rear bias which is why when you do an aftermarket adjustable prop valve you simple connect that line with the one out of the top.

astroboy

iTrader: (18)

So then why does the line come out of there and go to the dr side caliper if it is only a reference?

wildo

iTrader: (1)

Probably for packaging. The line to the LF caliper had to come from somewhere. Taking it straight off of the master cylinder means that you don't need another port on the proportioning valve.

There is effectively a tee built into the master cylinder. Looking at the diagram you posted, it would be as if there was a 2nd port labeled "To 1st brake circuit" right next to the one that is already there.