4 Wheel Disc Problem

[Hydratech®]

The tiny little vacuum booster I see in your images provides exactly that - negligible amount of brake assist. Even if you were somehow pulling 22" of vacuum to that puny little booster, you still aren't generating any particular assist.

Here is our tech on getting rear e-brake style discs into a better state of response (read through it further down):

http://hydratechbraking.com/braketech1.html

When I get into a vehicle such as yours, I would expect the brake pedal to be low if the rear e-brake is far out of adjustment (just like drum brakes being way out of adjustment). If the pedal is high and hard, then the rear e-brake is in a decent state of adjustment BUT your vacuum booster isn't delivering proper line pressures). I see where the rear brakes must be working somewhat, as the flash rust is worn off of the friction areas. If your pedal is low, apply the e-brake just to the point where you feel it starting to drag the car a little then take it for a test drive of about 50-75 feet. If the brakes feel substantially improved with the e-brake partially applied, then this speaks of excessive air gap between your rear pads and rotors (indicating they are still out of proper adjustment).



Want to supercharge your braking?

http://www.hydratechbraking.com/GM_2ndgenF_Body.html

It will blow your mind compared to that little mini vacuum booster - 2nd gen F cars always respond incredibly with the installation of a hydraulic brake assist system...