I am having an issue with my rear drum brakes locking up while panic stopping. My current setup is:
-Blazer front brakes w/ Powerstop Z23 pads
-Aluminum drum rears w/ large bore wheel cylinders for S10
-B Body large bore master cylinder
-New proportioning valve for disc/drums
-SS braided brake hoses
-Double diaphragm brake booster
-Vacuum canister
Suspension is in great working order: Bilsteins, Eibachs, Tubular control arms thoughout. I am running 255/40R17 front and 275/40R17 rear tires, same model.
I pull about 15" vacuum at idle and usually maintain 20-25" available vacuum while driving (vacuum gauge installed on A piller). I have bench bled the master multiple times, bled the system, adjusted the drums. I tested the pressure at my calipers and both read about 1500 psi. My braking has never been very good and now (since installing decent front tires) the rears are locking up during panic stops.
I have an adjustable proportioning valve I intend to install downstream of the stock prop valve to reduce pressure to the rear brakes. I am also considering installing C5 front brakes. Any insight on what could be causing this? I have been battling my poor brake performance since day one (about 15 years ago). I also notice my front brakes are dragging. I relieved pressure using the bleeder screw (to identify any bad hoses) but that did not help (on either side). Thanks for any help!
-Blazer front brakes w/ Powerstop Z23 pads
-Aluminum drum rears w/ large bore wheel cylinders for S10
-B Body large bore master cylinder
-New proportioning valve for disc/drums
-SS braided brake hoses
-Double diaphragm brake booster
-Vacuum canister
Suspension is in great working order: Bilsteins, Eibachs, Tubular control arms thoughout. I am running 255/40R17 front and 275/40R17 rear tires, same model.
I pull about 15" vacuum at idle and usually maintain 20-25" available vacuum while driving (vacuum gauge installed on A piller). I have bench bled the master multiple times, bled the system, adjusted the drums. I tested the pressure at my calipers and both read about 1500 psi. My braking has never been very good and now (since installing decent front tires) the rears are locking up during panic stops.
I have an adjustable proportioning valve I intend to install downstream of the stock prop valve to reduce pressure to the rear brakes. I am also considering installing C5 front brakes. Any insight on what could be causing this? I have been battling my poor brake performance since day one (about 15 years ago). I also notice my front brakes are dragging. I relieved pressure using the bleeder screw (to identify any bad hoses) but that did not help (on either side). Thanks for any help!