Low Idle RPM disappearing vacuum assist. | FerrariChat
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Low Idle RPM disappearing vacuum assist.

Discussion in '206/246' started by jselevan, Nov 8, 2025 at 12:18 PM.

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  1. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,883
    #1 jselevan, Nov 8, 2025 at 12:18 PM
    Have others noticed that at low (idle) RPM that the brake vacuum assist becomes non-existent? I have two Dinos to compare, and on one, at very low RPM (800 for example), the brake vacuum assist goes away. I have changed the check valve and inspected the ancient hose, but it persists. This is dangerous in parking lots or pulling into the garage.

    With a new check valve and no obvious loose clamps or hose leak, I'm fearing that I will have to dismantle and remove the vacuum assist servo and have it rebuilt. Have others experienced age-related failure of the large vacuum booster?
     
  2. Nuvolari

    Nuvolari F1 Veteran
    Owner Silver Subscribed

    Sep 3, 2002
    6,681
    Toronto / SoCal
    Full Name:
    Rob C.
    #2 Nuvolari, Nov 8, 2025 at 7:16 PM
    I have never noticed a difference in the amount of force required to push the brake pedal regardless of engine speed. This is the same for my Dino and 308.
     
    ghenne likes this.
  3. daviekj

    daviekj Formula Junior
    Silver Subscribed

    May 9, 2008
    490
    UK
    #3 daviekj, Nov 9, 2025 at 5:20 PM
    Jim, no, I’ve not noticed that on any occasion. Late 73 car, Original Servo, original brake balance, and original brake master before and after re-sleaving. Could the servo large diameter piston seal be sticky? I have had that on a 60’s Girling servo on another car. Took the seal out and it had gone hard. Replaced with new seal and solved. Kevin
     

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