making vacuum (1 Viewer)

[jblueridge]

I fitted a used brake booster to my bj74. I also plumbed in a second vacuum reservoir for the brakes.
With a vac gauge on the small line that runs to the vsv, it takes about 8 seconds to make 25 in. Hg
The booster has two diaphragms so each time the brake pedal is pushed, a lot of vacuum is used (lost?).
Even with the extra vac reservoir, the vac gets to about 10 in. Hg after 3 or 4 strokes of the brake pedal.

Is this normal?

 

[Bob Richards]

I think your rebuilt booster is not doing the trick... Do you have access to another 80 series to borrow just to see? I tried everything you have done even doubling up my reserves and it was still the darn booster. Once I swapped it my braking is awesome. My opinion is based off of my trial and error and it was a hard pill to swallow but that was my experience.

 

[jblueridge]

I think you are right.
I have a 2nd booster to try now.
I also bought a new aisin master cylinder.
If this rain ever stops I wiil get all that stuff installed.