Power Brake Booster Adjustment?

Discussion in '1970 - 1973 Specific' started by weim55, Mar 28, 2017.

  1. weim55

    weim55 Member

    42
    1
    Feb 23, 2017
    '70 Z28 and what looks to be a stock replacement booster and master. The master cylinder will not fully retract with foot off the pedal. Pushrod at the pedal into the booster is adjusted correctly and the booster is retracting as it should. Is the Pushrod from the booster to master adjustable? If so, possible without disassemble of booster?

    Thanks,

    Steve weim55 Colorado
     
  2. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

    25,259
    284
    Feb 26, 2004
    Bloomington, MN
    Make sure the pin in the master cylinder side of the booster is seated correctly.
    (It may have jiggled out of place during transport.)
    The inside end of the pin is cut down to a shoulder and the center "peg" fits into a metal part inside the booster.

    Also... Some boosters came with two different length pins for specific applications. Did yours?

    Grab the end of the pin with a pliers and try to rock it sideways.
    If the inside end of the pin moves... It's not seated correctly.

    If only the round end of the pin is visible and you can't get a hold of it... It's probably seated correctly and the correct length.

    The only proper adjustment for that pin is a different pin.
    However....
    A washer under each ear of the master/booster junction can take up the extra pin length.
    (It's a quick fix for a long pin before you get the right one.)
     
  3. weim55

    weim55 Member

    42
    1
    Feb 23, 2017
    I did the washer trick behind the master cylinder mounting ears to bleed the system. Can I see the pin you are speaking of with the booster still mounted on the firewall, master cyl. removed??

    Thanks,

    Steve weim55 Colorado
     
  4. weim55

    weim55 Member

    42
    1
    Feb 23, 2017
    Oh wait a minute, you're talking the male pin that fits into the female piston if the master, yes?

    Steve weim55 Colorado
     
  5. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

    25,259
    284
    Feb 26, 2004
    Bloomington, MN
    Yes.
    Unbolt the master and it's right in the middle of the booster.

    upload_2017-3-28_14-16-11.png

    Notice... The booster pictured comes with an extra one of a slightly different length. (bottom of photo)

    If it's the wrong pin or not seated correctly... The master won't return to it's normal "at rest" position.
     
  6. weim55

    weim55 Member

    42
    1
    Feb 23, 2017
    Checked it, I'll bet your on the money. I think it's got the wrong pushrod.
     
  7. weim55

    weim55 Member

    42
    1
    Feb 23, 2017
    Yup, the pushrod measures out at .0900" too long. The booster looks to be a China repop that came with the car.

    Steve weim55 Colorado
     

Share This Page