Rear Disk Brake Question

[pontiacgp]

What master cylinder are your guys using? I messed up when I said the proportional valve would cause the disks to drag, I don't know what I was thinking. The residual valve is in the master brake cylinder. The disk/disk and drum/disk proportional valve meter the pressure to the front and rear brake differently.

 

[axisg]

stock 84 SS unit for me

 

[oldsmobile joe]

i upgraded the brakes on my 79 calais. so i started with the factory master and dual diaphragm booster that came with the car. . but it had a long pedal travel and weak feeling brakes. like i had air in the system or the feeling of misadjusted drum brakes. so next i switched to a quick -take-up master and single diaphragm units that i had laying around from a low mileage 86? monte ss. the pedal feel got better but it still felt wrong. next i switched to a new master that i was going to put into my current winter project, this master was designed for a c3 vette with 4 wheel discs. this gave me the best feel and pedal response. next i will switch my booster back to the dual diaphragm.
at no time through all of this trial and error did my rear brakes feel like they were dragging.