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I see several people are having trouble bleeding brakes.
Especially the rears
Me too.
What I have done
Started with power drums and replaced them with discs on all four corners
Replaced all five hoses, Master cyl "RAYBESTOS MC36306", new disc/disc proportion valve.
Benched master cylinder.
Kept the original booster and hard lines
Re flared ends to fit
No leaks
Bleeders are up
Emergency brakes are working
Front brakes work.
Have not seen the rear calipers move
We have had several sessions of 5 pumps and release.
Still getting air on rear brakes
now we have resorted to a harbor freight vacuum bleeder
Sucks air and fluid right out of the master cylinder from the right rear
IT HAS Not gone dry not once.
I know its hard to believe, I have been on it to keep it full.
we have ran 2 quarts through and it is not showing any signs of slowing down
What have I missed?
Even if the the master and proportional valve where wrong it would still clear up with no air.
I have had to use this approach on 2 cars now on the rears. Have a helper for this one. Basically you are going to do it the old fashioned way, open bleeder, helper pumps pedal once - holds pedal in down position, close bleeder, helper releases the pedal. Rinse and repeat until you get no air out of bleeder. Keep an eye on the reservoir so it doesn't go dry. Harder this way, but I have never had it fail.
I started with the pump and bleed It just wasn't clearing out
Spent hrs not seeing any results.
Thought about jacking the back up a couple of feet to help the air rise to the bleeders.
Yea starting to get desperate
My bad experience with rear brake bleeding was due to the combination/proportioning valve. The piston inside moves and blocks fluid to the rear brakes. I was unable to get the piston to center up so the brakes could be bled. I found a tool that screws into the hole where the brake failure connector is located. I removed the connector and used a small screwdriver or pick to move the piston back to center and inserted the tool to hold the piston in place and then had no problem bleeding the brakes. Once through bleeding remove the tool and install the connector and you should be in business. The tool looks like this.
Did you bench bleed the master cylinder first? Ya gotta do it!
At the 2017 Olds Nationals, the guest speaker had lots of stories to tell and one was how to bleed the rear brakes with a dual master cylinder. Let the front brakes run dry, bleed the rears, then refill and bleed the fronts. The idea is that the front brakes will engage and not let the brake plunger move far enough to force the air out of the rears.
Another option is to use a reverse bleeder that forces fluid into the brakes through the bleeder valves at the wheel cylinder.
If you have the Cadillac rear calipers, you likely do not have them adjusted enough. They can seem to be grabbing but still too loose. Only takes a tiny bit of slop to use up your pedal volume.
I have the rear disc brake kit from speedway on a ford 9” in my 55 88, and spent weeks screwing around with boosters, master cylinders, proportioning valves, and bleeding gallons of fluid through the system.
Turned out there was a different method of adjusting the e-brakes that worked. Instant brakes......
Yes I did bench the master
never had this much problems before
Running the fronts dry make good sense. they sort of self bleed and pumped up without trying
I am going to drain them and suck air into there system and re bleed the rear.
thought about the E-brake adjusted it early on just to make sure the piston moved.
I even unscrewed and reset the calipers just to make sure they didn't get rusted while waiting to be shipped out.
Wow lots to think about if these guys are are having the same difficulties
Got Brakes
Yes they are working
Wore out the little Harbor Freight vacuum bleeder
It doesn't like brake fluid in the piston
Ate the rubber piston
I can pop a tennis ball with my right hand now
Replaced the Master with a Vette style master so it would hold more fluid
Pumped the emergency about 100 times
Bought another bleeder
Wrapped the bleeder screws with Teflon
Seems their threads are not sealing during the vacuum.
Worked my way around the four corners and pushed the pedal a few times.
It took about three refills and then there was no more bubbles.
I got excited leveled the fluid and started her up
pedal went to the floor with no resistance.
Bummer worse than before.
Pumped about 4 more times then it happened
I got brakes
Hard pedal
Smooth stopping
feels good
Emergency brake is still a little loose but It has brakes and will address that next
The "pneumatic brake fluid bleeder with auto refill kit" is cheesy, But it does work. not as much vacuum pressure as the little one. but consistent.
It was a lot cleaner then the little one and not bad for 33 bucks
