67 68 Camaro manual drum brakes

[JohnZ]

I just installed a new master with a rear check and after bleed down good the rear brakes would drag bad and hardly release. Thought it to do with RPV so pulled it and they now release fine. The aftermarket I removed didn't have one either.
Any thoughts or ideas?

Must have been a bad RPV. Without one in the rear port on a disc/drum system, you'll probably have longer pedal travel and an obvious case of "front brakes first" (nose-dive).

[bc69]

Well this might be hard to believe but, they operate fine with it out. Really don't know why,  but does.
And the one I pulled was a new one. ??
I would think it would have to do with the spring. Rubber ok and opens in the application of brake and that worked. Has anyone had kits that the valve spring was maybe to strong it allow release?

[Steve68]

Question: you are sure the rear drum brakes are actually working with the RPV out?  If they are then there must be some residual pressure there somewhere if you don't notice any nose dive or have a longer pedal travel than normal.  How far does the pedal travel before you get rear brakes to engage?  Have the lines to the rear been replaced to your knowledge?  How about the switch assembly (right under the master cylinder).....has it been replaced or is it the original?  Any possibility either may have some buildup in them?  You bled something, was it the master or at the rear wheel cylinders?  I suppose if there is some restriction and since the master is higher than the rear cylinders there might be enough head pressure to keep the cylinders out but I sure wouldn't want to rely on that.

Steve

[bc69]

all good questions Steve. Can't give you a answer to most other than good pedal and no nose dive. Have a gravel drive and they seem to work together. This car had the duel piston calipers and I'm wondering if this is helping to even things out. The thing that still bothers me is the PRV not allowing a release of rears.