Brake question

[bugsy]

I had some issues with not being able to get brake fluid to the rear brakes for our 70Z. I had the master rebuilt, the boostercleaned and new diaphragm. Front calibers rebuilt, rear wheel cylinders rebuilt. Combination valve rebuilt, all lines cleaned out and flushed. Put everything back on, bench bled master cup. Hooked my vacuum bleeder up and I get fluid and air. Gravity bled all 4 corners. Pushed the brake pedal in with a piece of 2x4 under the brake pedal. Pedal still goes down to block of wood and I can hear the rear drums move. Soft pedal thinking I have air in the master?No leaks anywhere. Anybody ever have this issue. Think I'm missing something. Any help is very much appreciated

[Lee Stewart]

It sounds like you are doing this by yourself. Any chance you can get someone to help you to pump up the brakes before you open the bleeder valves? At the same time you can take a plastic mallet and tap on the calipers to help dislodge any trapped air bubbles.

Did you change to a Dot 5 silicone brake fluid?

[ZLP955]

Did the MC rebuild incorporate a residual pressure valve in the rear port?

[L78_Nova]

I've had difficulty with those combo valve set ups. Often easy to get "driveable" but difficult to get proper "hard stop" performance.
I will generally loosen each line connection starting at the master and work back to burp a little fluid. Seems a gulp of air can be trapped and just surge back and forth in the line and make for some strange rear brake performance. It's a two man job for certain and go eeeeasy on the pedal or you will wear the fluid. Oh ya... lots of rags.

[bugsy]

Lee thanks I will try that. I am getting fluid out of all 4 bleeders, air is trapped somewhere. Not sure about the residual valve. I will call the guy at Karps in Calif today. They do nice work

[PeteLeathersac]

'

Are rear brake shoes adjusted out to almost grabbing when rotating drums as this can make the difference of "getting pedal" in the first few strokes thus resulting pressure for bleeding system.
Bench bleed again if Master on the car then "with pedal", add lines and top up fluid then w/ all bleeders confirmed closed, burp Right Rear first then LR rear then RF and LF last.
As above, two guys work best, especially when troublesome systems as sometimes guy one needs to pump/pump/pump for pedal then guy two immediately release/bleed and quickly tighten...then back to guy one and repeat all a few times in a row until firm pedal achieved.
Make sure fluid level up after each corner burped and good luck!

~ Pete

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[bugsy]

Thanks to all of you.

[racer67x]

did my Nova with all new lines..etc.
and had the same problems,remembered an old trick.
take a plastic bottle,fill it about half with brake fluid...drill a hole in the lid or tape it up and run a piece of rubber hose to the bleeder,pump up the peddle and lock it with whatever you are using..crack the bleeder while keeping the hose submerged,
leave it open then slowly release your pedal lock.
it will let fluid pull back in from the bottle and works pretty good if by yourself.
after a few times you should be good.
hope I explained it right..lol
good luck