brake woes

[tmckeon88]

Hello all and sundry who know more than I-

I have a '69 IIA 88 (with the dual brake system and vacuum booster) and I have had a chronic problem with a lack of brake pedal pressure for years. I have replaced virtually the entire brake system -wheel cylinders, shoes, adjusters, pipes, master cylinder, etc., and still I have a lot of fairly weak pedal travel until it gets neat the bottom then I can get some braking power. I've bled and bled like a medieval barber-surgeon, without much improvement. Now, the strange thing is sometimes the pedal has great pressure and I can feel the brakes apply just about instantly, and I have tons of braking power. This leads me to conclude it is not the adjustments at the wheel. Could the vacuum boost unit be bad? It's old, certainly. Any thoughts or advice would be great -

Thanks,
Tom

[Jim-ME]

I would guess that either you have a vacum leak from the manifold to the booster or your booster has gone bad. Hope it's just the vacum leak.
Jim

[CliftonRover]

are the brakes only strong if they get used a lot? if so it could still be the adjustment at the wheels. I struggles with the djestment on the master cylinder on the last truck i built. the shaft was longer and not allowing the fluild to pass both ways.