flexing the booster

Discussion in '40- & 55-Series Tech' started by snailwagon, Aug 9, 2005.

  1. snailwagon


    Likes Received:
    Jun 11, 2004
    high desert, ca
    I've had a never ending brake problem, which makes me just stare at brake parts on my pig from time to time. However, I never really paid much attention to staring at the booster when the brake pedal is pressed. So I had my wifey press the brakes with the engine running/booster pressurized (mini-truck booster/fzj80 mc) while I had a staring contest with my brakes. When the brakes are pressed, the master cylinder internals move until major pressure is needed to operate the disc brakes, then the body of the booster actually begins to move and entire quarter inch or so. Less pressure is needed to flex the power brake booster body than is needed to push fluid through. Anyone seen this before? The booster itself holds pressure well and does not seem to leak.

    Another wierd thing happened a few days before this. I thought I might of had air still in the mc, so I pulled it off, bench bled it again, and bolted it up. Then the brakes wouldn't bleed, they would only drip like when being gravity bled. So off went the booster. Then I noticed if the firewall side pushrod on the booster was pressed, the mc side pushrod would not move. Went inside, drank beer, ignored it till the next day. Somehow it repaired itself. Can the pushrods really fall out of alignment that easy? what the hell happened here?
    Needless to say, the junkyard booster will be gone this week.
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