Hey Guys,
I looked around the forums and couldn’t find the information for my specific issue. I am replacing my single chamber master cylinder with a dual chamber master on my 1953 3600. The master is under the floor but I have installed a remote fill up on the fire wall. I have 4 wheel drum brakes (original to the truck).
When I originally rebuilt the truck I replaced the entire braking system from the master to the drums. Recently I had the brilliant idea of upgrading the brakes to a dual master as i drive the truck a lot more since i retired. The old system did not have residual valves but is stopped pretty good. The new system i bought came with 10 pound residual valves (appropriate for a 4 wheeled drum system as i have read). I have been having a great deal of difficulty bleeding the system. I even tried a pneumatic vacuum bleeder. I get a lot of air out but the pedal is still soft and stopping is scary.
Is it possible to have air leak into the system when no fluid is leaking out? Do i really need the residual pressure valves with the firewall mounted remote fill reservoir? Is there another reason I keep getting air out but the pedal is still so soft?
I bled the brakes for hours and still air in the system. I put a little teflon tape on the bleeders to make sure they weren’t leaking air in as i bled. I plugged the master cylinder and the pedal is rock hard so it’s not the master.
I am in the process of re-plumbing the system to see if maybe I caused an air trap some where but I would think the pneumatic vacuum bleeder would have pulled any trapped air out.
The real question is why is there air after all the bleeding? I have essentially replaced all of the fluid at this point and still have air in the lines somewhere.
Do I need the residual Pressure valves? Could they be the culprit?
Thanks much for any advice᠁ I am pulling my hair out at this point.
Best
Rich
