Help on installing new master brake cylinder reservoir seals | FerrariChat
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Help on installing new master brake cylinder reservoir seals

Discussion in '308/328' started by 330gt, Jun 5, 2025 at 6:13 PM.

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  1. 330gt

    330gt Formula 3

    Nov 12, 2004
    2,085
    Seattle, WA
    Full Name:
    Kerry Chesbro
    #1 330gt, Jun 5, 2025 at 6:13 PM
    Last edited: Jun 5, 2025 at 6:19 PM
    On my '78 US 308, I had one of the sides on the brake reservoir leaking where it fits into a seal in master brake cylinder. I removed the reservoir using a flat bar which took quite a bit of force. This left the seals in the master cylinder.
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    The reservoir has two barbed tubes that fit into seals installed in the master cylinder.
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    My questions are:
    1. Do you install the new seals on the reservoir first and then fit the whole assembly into the master cylinder?
    2. If not, then do you install the new seals into the brake cylinder and then force the barbed tubes into the seals?
    3. How close does the reservoir fit to the master cylinder? Before I took it apart, the reservoir could wiggle front to back and was not fit tight down on the master cylinder.
    Regards, Kerry
     
  2. bitsobrits

    bitsobrits Formula Junior
    Silver Subscribed

    Nov 12, 2011
    717
    Omaha, NE area, US
    Full Name:
    Steve
    #2 bitsobrits, Jun 5, 2025 at 7:37 PM
    Kerry,
    I fit the seals into the master cylinder first, then install the reservoir. I put just a slight smear of brake fluid on the reservoir barbs to ease their entry. So what you call Option 2. Not sure your Option 1 is even possible. The bottom of the reservoir sits in close contact with the seals. The reservoir on my car can be somewhat wiggled about after the new seals, but no leaks.
     
  3. 330gt

    330gt Formula 3

    Nov 12, 2004
    2,085
    Seattle, WA
    Full Name:
    Kerry Chesbro
    #3 330gt, Jun 6, 2025 at 6:17 PM
    Exactly as you suggested. Putting seals into the master cylinder required pushing in at the bottom in order to get the seals started. That would not have been possible if trying to put them on the reservoir and installing everything at once.
    The only hitch was that I dislodged the washer tube to the sprayer on that side. Putting that back on with the reservoir in place was difficult. I wish I had noticed it earlier.
    Anyway, done and no leaks.

    Thanks, Kerry
     

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