1957 trying to bleed brakes; getting little fluid

[vernz]

I'm going through my brakes to address a hard pedal. I've replaced the master cylinder and rebuild the brake booster. I bled the booster with no problem, but now I'm at the rear wheels and can barely get any fluid flow. I'm using a hand vacuum pump and pulling 15 inches of mercury plus pushing on the brake pedal but I only got a little fluid on the passenger side after a long time and none on the drivers side. My goal is to change out all the fluid (DOT 3). I removed and checked the bleed valve on the passenger side and it is completely open. Am I doing something wrong or is it time for new wheel cylinders? Thanks, Vern

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[74 Harley]

You need to look at the rubber brake lines as well. When they deteriorate the passage can become severely constricted. This leads to brakes not applying and /or dragging.

 

[Ward 57]

74 Harley is correct. The flex brake hoses can swell from the inside out. The other contributing factor is that when replacing wheel cylinders somebody will put vice grips on the flex lines to keep them from leaking, will crush the interior of the line but not visible from the outside.
I'm having all my flex lines from the booster to frame, front and rear lines replaced. The fronts are probably 30+yrs old and the rear and booster lines are original. No blockages nor leaks but don't trust them to not crack at the wrong time. Not a big job but will have my shop replace them as they can do it in a snap but if I do it, it will take more time to replace and bleed right at the beginning of the drive & show season. Worth the price and no harm to my wrenching ego.

 

[vernz]

Thanks for the responses. I was wondering about the flexible lines. This makes me think thqt I have not had very funtional rear brakes for some time now. I don't have a real good way to get under the dcar and work so I think I will get my mechanic to replace all the flexible lines. Vern

 

[Ward 57]

Time to invest in some jack stands and a floor jack. Assuming you have a hard flat surface to execute tinkering. It will be an investment you will thank yourself for later oh and a lay on your back creeper.

 

[CSPIDY]

If you don’t know the condition of the wheel cylinders
now would be a good time to have them checked as well

If an old car won’t go,
No harm will come of it
If it won’t stop it is doomed!