The Thread was started because many folks had inline Master Cylinders and Proportion Valves and didn't really understand how it works .... I just explained how it works for the people that use them....
The more advanced Group will go with the Balance Bar in the Brake Pedal and use a Knob to adjust Front to Rear Bias of the Brakes.... and that is done by moving the Pivot point in the Brake Pedal towards the Master Cylinder that you want more pressure from.
And some of us will use Both as we have the ability to use the Balance Bar for a major adjustment and a Proportion Valve for Fine tuning.
Here we see the Dash and below the Dash is a Central Dash that is much Thicker then the dash. mainly because the Standard Dash is so thin that pulling or pushing on the dash will cause it to flex and not operate the device you are trying to open or close ie; Fire System or even turn the knobs for Power or Brake Bias Adjustment.
Here's a much closer photo of the Central Dash, it's made out of 1/4" Thick T-6 Aluminum so there is no Flexing going on....and of course you see the Brake Bias Knob to move the Spherical bearing in the Brake Pedal to one side or the other in the brake pedal... (To the Front master cylinder or Rear master cylinder), and the Main Power Switch as well as the Fire System Knob