[Healeys] BJ8 Brake booster fail locks brakes on

[Chris Dimmock]

Hey guys,
Ever had a BJ8 brake booster fail so it locks your brakes on?
My brake booster (BJ8 std type) effectively pushed the pedal high, and locked
all the brakes on. Solid
Pushing hard on the pedal released the brakes, but next time you touched them,
same thing. 4 wheels locked solid.
This isn't a diagnosis question. I had replaced calipers, hoses, rebuilt wheel
cylinders, rebuilt the brake master cyl, replaced the reseviour with a new
one, and fitted a rebuilt BJ8 Booster. fitted new linings and shoes. And a New
one way valve in the booster vacuum line.
Thats when the problem started...
So I re rebuilt master cylinder. Twice. Checked and double checked everyting
Checked the booster one way valve.
Glimmer of hope was disconnecting the "new" booster. Problem vanished - but no
booster.
Today I put my old booster back on. Std BJ8, rebuilt 14 years ago. Brakes are
now perfect again.
This preventative maintenance has hairs all over it....
So the question is.... What's wrong with my newly rebuilt BJ8 booster that it
doesn't release the vacuum????
Ideas? Your experiences??
Thanks in advance.
Best