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Technical Help with my Master cylinder

Discussion in 'The Hokey Ass Message Board' started by scottrodz, Apr 9, 2014.

  1. scottrodz
    Joined: Nov 7, 2007
    Posts: 9


    I know someone out there can help me with this. I am using a 1962 Chevy Brake Clutch Dual Master Cylinder (out of a truck I think) mounted on my firewall of my 1930 Model A. The bore size is 1 1/8 inch on both the clutch and the brake side of the cylinder. My problem is that the Hydraulic-throw out bearing needs the clutch side bore to be 3/4 inch. I have a machine shop here that can sleeve the cylinder down to 3/4 inch but what do I use for the interior piston, seals and spring? Do they need to be the exact same length as the ones I took out? I know that something out there will fit but nobody in their spec sheets give these dimensions. What have other people used? Thanks for your help on this...
  2. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,695

    Mike VV
    from SoCal


    The purchase of a "rebuild" kit should provide most everything you need. You just need to know the "I.D." of the sleeve you are using.

  3. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    from Phoenix AZ

    Even easier ,use the matching external clutch slave cylinder for that master cyl. You will be happier in the long run.
  4. silversink
    Joined: May 3, 2008
    Posts: 912


    Much easier to change out the slave cyl. than redoing a master cyl. got beat--slow typer
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  5. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547


    I would match the set to the original slave , unless you have a very patient old parts guy and a bunch of kits you can go thru to make one up . and a good machinist that can down size the originals
  6. Yup, and remember to switch the guts in the MC from side to side!
  7. scottrodz
    Joined: Nov 7, 2007
    Posts: 9


    So if I keep the MC at 1 1/8 and use a 3/4 slave then that should solve the problem??
    thanks for your help on this may be simple to you but it is hurting my brain!
  8. I will make it even easier. The stock slave for that MC is a 1 1/16". The Wagner number for that is F124369 with a rebuild PN of F130286
  9. scottrodz
    Joined: Nov 7, 2007
    Posts: 9


    Correct me if I'm wrong, but If I am using a Hydraulic throw out bearing then I don't use a I'm back to reducing the clutch side of the MC to 3/4inch and finding the guts to go inside....or am I wrong on there another way??
  10. sdroadster
    Joined: Jul 27, 2006
    Posts: 259


    I learned a long time ago to keep it simple. If (when) hydraulic throw out bearings start to fail you will have to disassemble the car. Use the correct throw out bearing for the application, and the appropriate slave cylinder.
  11. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,874


    ^^^^^what he said^^^^^
  12. Do it like the factory. Use a throw out and slave instead. I have seen in person (and seen here) many faulty Hyd throw outs. I got to help a rodder swap one on the road. Even with the hoist and right tools it was a pain in the butt on what should have been a fun trip.
  13. Phastphil
    Joined: Jan 9, 2008
    Posts: 59


    EVERY hydraulic throw out bearing I have had in a vehicle has failed, one OEM went 90k, the others much sooner, the last, my roadster project, lasted one week, had to pull the motor to fix, at which time I converted to a right hand slave setup. Slave cylinders are not infallible either, but, are easier and cheaper to fix. I will NEVER use a hydraulic bearing in a project again. You may get lucky and have one last but the odds are against it. Send it back, put in a slave setup if at all possible.......

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