Installing drivelines?

Discussion in 'Powerboats' started by JordieS, Nov 7, 2011.

  1. JordieS
    Joined: Apr 2011
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    JordieS Junior Member

    Dear everyone,

    I've just been wondering how people connect the engines to the drives when building a boat be it a surface drive, Sterndrive or inboard/shaftdrive. When looking at pictures of bare new engines on the internet or at the boat shop, there is no flange or anything on the small prop shaft that pops out the back of the engine, there is just a small rod coming out (I wish I could find pics to explain better).

    How do people join it all together? Weld flanges on to the crankshaft? How is it done?

    Also if you were to order a engine with a sterndrive say Merc 135 with Alpha One, would it pretty much be a kit (all the pieces needed to connect engine to drive) or would you need to fabricate flanges, get U-joints etc?

    If anyone could help clear things up it would be a huge help.

    Thanks again
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Each engine and drive system will have several pieces that make up the drive assembly. Familiarizing yourself with the differences can be as easy as a repair manual on the system you'd like to employ.

    For example a Mercruiser stern drive will have a bell housing, transom plate, gimbal housing and gimbal ring, all as a bolted together assembly that the actual drive (upper gear case) mounts to. The drive itself is motivated by a short drive shaft that's bolted to the input shaft of the upper gear case and the engine side is a spline shaft (typical).
    [​IMG]
    This is a complete Bravo transom assembly. It is attached to the boat and the bell housing, which is attached to the engine. The drive and it's controls (shift, tilt and trim cylinders, etc.) bolt directly to the transom assembly.

    Surface drive is similar in that it uses a bell housing and transom plate/assembly to bring the engine output through the transom. In fact you can convert a stern drive to surface drive fairly easily, by pulling the gimbal housing, ring and other related hardware and mounting an adapter and surface drive assembly.

    This is a broken drive assembly;
    [​IMG]
    Where you can see the upper and lower gear case unit and the transom assembly. The gimbal housing and ring are broken of course.

    This is a surface drive conversion on a Bravo stern drive;
    [​IMG]
    It simply takes the Bravo bell housing and I think portions of the transom assembly and adapts this to the surface drive system.
     
  3. JordieS
    Joined: Apr 2011
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    JordieS Junior Member

    Thank you so much PAR, but also if you buy a Mercury sterndrive engine and the appropriate drive, would it just be a complicated bolt on or would you need to get custom parts made to join it all together? On the Volvo Penta websites and the Mercury marine websites, they have pictures of the engines and drives joined together with a clear plate acting as the transom.

    Can you buy a Volvo sterndrive or Mercruiser sterndrive with engine and drive as a whole and simply bolt it on sort of like an outboard or will you need to get custom parts made?

    Thanks
     
  4. IMP-ish
    Joined: Jan 2011
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    IMP-ish powerboater

    You can buy an engine and outdrive package or you can buy either alone.
    On the back of the marinized automotive engine you will see a bell housing (not the same as the bell housing of the outdrive). In the center is an engine coupler.
    The outdrive has a u-jointed splined shaft which slips into the engine coupler to mate the two. If you search you can find a manual which lists the dimension tolerances for installation: transom thickness, angle, engine dimensions for forward engine mount placement on the stringers.
     
  5. JordieS
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    JordieS Junior Member

    So it is pretty much just bolt on, no other fabrications required? It all comes in the package?

    Thanks a lot
     
  6. CDK
    Joined: Aug 2007
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    CDK retired engineer

    You get a pallet, a large carton and a booklet.

    The engine stands on the pallet together with some boxes containing all the hardware you need, the large carton contains the drive. On the carton is a template printed that you can cut out and stick to the transom.

    The booklet explains meticulously and step by step how you must proceed.
    In a normal installation no parts need to be made or purchased separately, except that they do not include a tool to vertically align the engine. That you must borrow or make yourself.
     
  7. JordieS
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    JordieS Junior Member

    Thank you so much CDK, have you had experience with doing this? Would it be the same with Volvo Penta?

    Thank you so much
     
  8. CDK
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    CDK retired engineer

    I've done this twice. Bought the engines in the USA from a boat builder who signed up with Volvo and still had a lot of Merc packages in his warehouse.

    Of course Volvo does it the same way. The boat builders are good with wood, resin and glass but normally have no facilities for engineering, so the engine supplier prepares everything for them.
     
  9. JordieS
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    JordieS Junior Member

    Thank you so much CDK, you have helped me alot

    Appreciated
     
  10. cyclops2
    Joined: Sep 2010
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    cyclops2 Senior Member

    Answer to the original question.

    The stubby shaft on the back of the engine has a VERY precision set of teeth on the shaft. They look stupidly small for the horsepower of a engine.

    Fear not.
    A flange with matching teeth on the inside, slides right on to the engine stubby shaft. No mechanical locks are needed. Some do have a snap ring. The transmission or the thrust bearing & a locking collar then hold the flange in the correct place on the shaft.
     
  11. whitepointer23

    whitepointer23 Previous Member

    in australia you have to take the boat to an authorised mercruiser dealer if you are looking at a new outfit. they don't give any warranty otherwise, i don't know what volvo's policy is. mercruisers have alignment problems if not fitted correctly and need special tools. volvo are much simpler in regards to alignment.
     
  12. JordieS
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    JordieS Junior Member

    Thank you so much everyone, if you have anyone keep the info flowing its such a help.

    Thanks
     
  13. IMP-ish
    Joined: Jan 2011
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    IMP-ish powerboater

    How has volvo simplified the alignment?

    With mercruiser, the tool I see them use is a simple special mercruiser rod which has all the right notches to fit in. I have seen marina mechanics spend two hours aligning but pros that do it daily do it much faster. It helps to have the magic touch.
     
  14. CDK
    Joined: Aug 2007
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    CDK retired engineer

    For obvious reasons most Merc dealers are very reluctant to lend out a special tool.
    An old drive shaft with the joint cut off and a piece of pipe welded to it works fine too.

    Because there only is vertical alignment to be done, 2 guys can do it in less than 10 minutes, half an hour if you work alone and want to spend 20 minutes climbing in and out of the boat.
     

  15. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    Par the reckon that steering helped break that bell housing.
    look at the geometry!!
     
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