1965 Special master cylinder help needed

Discussion in 'The whoa and the sway.' started by Mike Drew, Jan 14, 2019.

  1. Mike Drew

    Mike Drew Mike Drew

    All,

    My mom is the original owner of a drum brake non-power ‘65 Special. A year ago she had it converted to power brakes, and at the same time for the sake of safety the single chamber master was replaced with a tandem master.

    The brakes are now far too good! Modest pedal pressure is enough to throw you through the windshield. I suspect the master that was installed has far too much piston area, and is designed for disc/drum versus drum/drum.

    I can’t seem to find a tandem master for drum/drum applications. Can somebody point me in the right direction?

    Thanks!
     
  2. ragtops

    ragtops Gold Level Contributor

    https://www.amazon.com/Raybestos-MC...e=UTF8&qid=1547451846&sr=8-1&keywords=mc36373

    This is for a 1962-1966 Cadillac, they had a dual circuit, power brake, 4 wheel drum brake system before most other GM cars.

    There is also the depth of the hole in the piston for the rod coming out of your power booster to consider. It has to fit properly. The replacement boosters I have bought in the last few years, new and rebuilt, have come with 2 different length rods to use.

    I also call attention to Auto Zone website which clearly say the application for the master cylinder on a 1967 Buick Skylark with front disc and one for front drum. That also should work.

    Best luck
     
  3. Mike Drew

    Mike Drew Mike Drew

    I like the Autozone answer! Will give it a try. Thanks!
     
  4. philbquick

    philbquick Founders Club Member

    A power brake system has a larger piston then a non-power system. If it's too touchy maybe the master cylinder is too small.
     
  5. Mike Drew

    Mike Drew Mike Drew

    Yes but a disc/drum system uses a much larger piston than a drum/drum system. The current master piston is way too large. There is almost no pedal movement before you are thrown through the windshield, and the pedal is very firm. A smaller master bore will deliver a longer pedal stroke and a softer pedal, both of which are desperately needed. A drum/drum master is what I need....
     
  6. CJay

    CJay Supercar owner Staff Member

    I second the suggestion of using a 67 Skylark power drum master.
     
  7. sbrmd

    sbrmd Well-Known Member

    I had my '65 Sportwagon updated to a dual master cylinder a few years ago. It started out as a power brake car, and the master used was spec for a drum/drum '67 Impala. Worked perfectly: braking performance, pedal feel and travel all perfectly normal. Windshield still intact.
     

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