[bill plise]

Can someone please tell me on a manual brake system, disc front and drum rear with a corvette master cylinder are not the two systems independent of each other? bill

[RWENUTS]

Yes they are!

[bill plise]

Rwenuts, If the two systems are independent would not a pedal that goes to the floor after a week of sitting be caused by a defective master cylinder. I have a 30 model A coupe 350/350 with manual brakes disc front and drum rear {corvette cyl] . I have a miminal leak at the prop valve at the threads which could be the cause of the rears not pumping up but the fronts should keep pedal up, right? another question is do I really need a proportioning valve to begin with. bill

[RWENUTS]

Do you have residual check valves in place. 2#'s front. 10#'s rear.
Could be draining back to the master. You do need a prop valve to limit pressure to the back.
Front does 80% of the braking. You could get away with the residual check valves and an adjustable valve to the rear and then not use a prop valve.

[aosborn]

If you lose pressure on half your system, there will still be some pedal left to stop the car. But not much. If you set up your brake pedal to be able to utilize the full travel of the master cylinder that is as good as you can get. If your brake pedal bottoms out before the master cylinder does, you greatly limit your ability to stop when only half the system is working.

Fix all your leaks, re-bleed the system and then see how it all works out.

You will need an external 10 lb check valve on the drum brake axle if there isn't one in the master cylinder already. You will only need the 2 lb unit on the disc brake side if the master cylinder is lower in the vehicle than the disc brake calipers. The adjustable proportioning valve is a must as was previously stated.

Andy

[bill plise]

Thanks for the replys, yes I do have the 2 lb front and 10 lb rear residual valves in place and I will replace the Wildwood prop valveand bleed the sys again. bill