Problem with new Master Cylinder-Help? | FerrariChat
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Problem with new Master Cylinder-Help?

Discussion in '308/328' started by Big Daddy, Dec 6, 2009.

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  1. Big Daddy

    Big Daddy Karting

    Jan 3, 2009
    212
    Albuquerque, NM, USA
    Full Name:
    RJ
    #1 Big Daddy, Dec 6, 2009
    I had the master cylinder rebuilt on my '81 308 GTSi. I installed it Saturday and got help bleeding all the calipers. I bled several times, but still cannot get the brake pedal firm. There is some pressure because I drove the car and it is stopping, barely, but the pedal goes all the way to the stop.

    Is someplace a big air bubble could be hiding, like at the equalizing valve? I could not bench bleed the MC because of how it is installed, but I don't see how there could still be air in it. I put three quarts through the system trying to bleed it.

    I took all the wheels off to look for a leak, but I could not find any. The rear pads appear properly adjusted and the front pads are good also.

    I guess what I am asking is if there is any trick I am missing here? I don't know what else to do at this point.

    Any help is appreciated.
     
  2. twright

    twright Karting

    May 15, 2005
    225
    Indianapolis USA
    #2 twright, Dec 6, 2009
    Excuse my lack of Ferrari specific knowledge, however: Every other new master cylinder I have put in REQUIRED it to be bench bled. I tried one without bench bleeding it and the result was doing exactly as you're reporting.

    I don't understand how air stays in them if you don't bench bleed them, but it does.

    You have to bench bleed it.

    I now defer to Ferrari specific experience. Anybody know if Ferrari master cylinders are the same as everybody else's?
     
  3. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    6,872
    Full Name:
    Mike 996
    #3 mike996, Dec 6, 2009
    Pressure bleed the brakes - it's much faster and more positive than manual bleeding, doesn't require a helper and requires no bench bleeding of a new mastercylinder. Takes all of 15 minutes to do the entire system. You can buy quite inexpensive pressure bleeders that just attach to the cars tire and uses the air pressure in the tire to do the job. Yeah, they look/sound cheesy but they work fine. Can't imagine bothering with pumping brake pedals anymore - haven't done it in 20 years.

    Another way to do it is to reverse bleed - apply fluid under pressure at the caliper fitting which will fill the master cylinder from that direction. This is done frequently on motorcycle brakes.
     

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