68 Charger Brake Problem

Had brake line and master cylinder off, so engine bay could be painted. Now when we tried bleeding the brakes you can pump the pedal by hand real fast and get it to build pressure but once you quit for a few seconds the pedal loses pressure. Could I still have air in the line after bleeding them or is the master cylinder bypassing. I put disc on the front also and am using the proportional valve that came on the car for drums all the way around. My wife and father-in-law was doing the bleeding while I was working on wiring.

Did you bench bleed the master? You need the disc/drum Proportioning valve. If you must, then pressure bleed them. Tim

Also need a disc drum master.That and make sure the disc bleeders are facing up.They will never bleed if they arent up.I know.Rocky

What's the difference in the all drum and the disc/drum

"bench" bleed the M/C (both ports) on the vehicle then the front half (RF 1st then LF) then the rear half (RR 1st then LR). Caveat; have your helper open the bleeder just the right amt to let the air/fluid out & instruct him to hold the pedal until you close the bleeder and I like to have him use a block of wood under the pedal so it's immobile and he does not push the rubber seals past their normal wear area which over time may hasten their demise. A bit picky but (1) my opponent may not be so meticulous and (2) I know Murphy's law 1st hand. Get it up & running then you'll be in an excellent position to decide if you need a prop valve change

All right changed master cylinder and bench bled it and still the same thing after gravity feeding, kind of confused about if I've got the calipers on the right side because on either side the bleeder screw is higher than the banjo bolt. Should the banjo bolt be pointing down toward the control arm or pointed up close to the control arm.

I thought you always started at the furthest point from the master cylinder which would be passenger rear.

Pressure bleed them, it sometimes works where conventional bleeding wont. Tim

On a 1968 Charger the thing that people ASSuME is the proportioning valve is nothing more than a distribution block, the same one is used for both drum and disc brakes with an extra valve added into the rear line when the car is equipped with disc brakes.

The proportioning valve didn't appear on a B body till the 1970 model year.

Sorry for taking so long to get back, the problem was I had the calipers on the wrong side. My father-in-law has a 68 Coronet R/T with a disc brake conversion and I put my calipers on the same way he did but it wouldn't work for me. as soon as I swapped sides I had pressure building up. My banjo bolts are right under the control arm and his is closer to the steering tie rod bars. Hopefully this will help out someone else, so if you can pump up the brakes real fast and get pressure then let off and lose pressure then you might want to swap your calipers around. And i'm using the proportioning block that origionally came on the car, but haven't had enough time to drive it hopefully that will be tomorrow to see how the brakes feel without a proportional valve.

i think the prop valve you are talking about is the residual valve/line splitter (for the front)----- drum brakes have 12 in lb column pressure to keep the brake shoes close to the drum---when you go to discs you only need 2 in lb column pressure to keep the pads close to the rotor----you effectively dont need a residual on the front lines so you run the lines straight to a tee for both front calipers-----the way you say you are set up now your front brakes will lock up----dont go to far in your test drive you dont want a long tow home---as far as switching sides what you did was to put the bleeder zerk on the high side to let the air out--the way you had it the bleeder was at the bottom--it let alot of fluid out during bleeding but that nasty air pocket never disappeared----bob