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Flathead flywheel

Discussion in 'The Hokey Ass Message Board' started by metaldave, Jul 12, 2013.

  1. metaldave
    Joined: Aug 27, 2011
    Posts: 81

    from michigan

    I need help! I am building a late Merc Flathead. I had the engine and flywheel balanced. I tried to put the flywheel on and it binds on the block . I have another flywheel that I can see is different on the backside and it will fit. It is drilled for an 11 inch clutch. My question . Can this flywheel be redrilled for a smaller clutch? Will switching flywheels mess up my balance job and what could I do about it? What kind of flywheel did I spend my money on that I cant use? It is drilled for a 10 inch clutch.
  2. JM 35 Sedan
    Joined: Feb 2, 2012
    Posts: 36

    JM 35 Sedan

    If you can throw some pictures up here, front and back shots, of the flywheel that hits the block, maybe someone could ID what you have. A good machinest can re-drill that other flywheel for a 10" or 10-1/2" c&pp but it needs to be drilled, tapped and counter bored like the original holes. Also, if you do change the flywheel you will probably need to resurface the clutch face and have it balanced as well as the pressure plate. JMO
  3. jetmek
    Joined: Jan 12, 2006
    Posts: 1,847


    check the width of the ring gear...49 -53 has a 5/8 wide gear, 48-back has a 7/8 wide gear and are not interchangeable only 49-53 f-1 truck and 59ab has 10" p-plate. it mite be hitting idler gear cover bolts check for that . you can redrill those ...i made a drill jig for 9 and 10" long style clutches..
    Joined: Jul 4, 2006
    Posts: 241


    As long as the shop that balanced the ass'y didn't do any correction on the flywheel to correct the crank balance you should be OK.

    The crank should be balanced independent of the flywheel and the pressure plate. Some shops like to take shortcuts however, and this usually makes for a "catastrophe".

    The flywheel on the Flathead is an independently balanced part. You can balance the flywheel and the pressure plate as a single unit, but neither incorporated with the crank balance.

    Thanks, Gary in N.Y.

    P.S. Haven't redrilled any Flathead wheels recently but it can be done to accomodate a different clutch/pressure plate combo. After any machining on these pieces they must be rebalanced or at least "run-up" and checked!
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