56 T Bird Brakes

G

GAR64

Senior Member
You guys gave me good advice last year when working on an issue with my brakes. Finally getting back to this and have another question. Original issue was brakes hanging up and I was trying to determine if it was a bad booster (stock Midland) or perhaps pedal pressure on MC. When i removed old MC, (top could NOT be removed), I found little fluid inside, so I know it had been very low on fluid. I replaced the MC (bench bled) and decided to see how the brakes were before messing with booster. Seems easier to diagnose one variable at a time. Anyhow, I then started to bleed the system starting at the booster. When bleeding the booster, I could not get anything more than a few drops of fluid (ugly fluid). Just air. Is this indicating some kind of leak/bad seal in the booster? Appreciate any guidance.

greg
 
I was a mechanic for 30-years. A single brake system is extremely important that "everything" is in good working order. Do yourself a favor and replace or rebuild everything in the brake system. If the master cylinder is all gooey and in need of a rebuild you can bet the wheel cylinders are too. Also replace the brakes shoe return springs and do not stretch them with plyers that leave marks on them or where they will break on those little marks left by the plyers. Use brake install tools that don't put marks on the springs. New springs only last a maximum of ten years before they will start breaking. If you can save the "original" master cylinders and wheel cylinders with the "original casting numbers" by rebuilding them, do it. If they have already been replaced with aftermarkets parts by now, then it doesn't really matter if they get replaced again. I'd replace the brake hoses too if they look original.
 
The booster diaphragm only furnishes mechanical assistance to the master cylinder, aided by vacuum. No brake fluid in the booster portion itself.
 
If you block the output line from the master, do you get a high hard pedal? I hate to say it, but in today’s world a new master isn’t always what it should be. It might bench bleed fine, but not be making full pressure. Generically, at least 1000bls for 4 drum systems, probably more like 1500-2000 with a strong leg on the pedal.

The best way of course is a pressure gauge.

The booster hydraulics could also be bad of course.

I’ll second everything Flathead said. Old neglected systems continue to fail every time you fix the first weak link.
 
Last edited:
Als48 said:
The booster diaphragm only furnishes mechanical assistance to the master cylinder, aided by vacuum. No brake fluid in the booster portion itself.
Click to expand...
Even when the fender mounted booster is a separate part of the hydraulic system downstream of the master cylinder?
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