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Thread: External Alternator

  1. #1
    Senior Member
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    Nov 2019
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    Leavenworth WA
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    Default External Alternator

    I am installing the Rotax external alternator on my 912is. In looking the the mounting of the ring to mount the V belt pulley to the engine prop flange, it appear to me that I use what I think are the press fit bushings that came with the prop spacer. For those of you who are using the external alternator, is that how yours is? A different method? Also if those aren't press fit bushings (the instructions are pretty much non-existent here) please let me know.

    Thanks

    Gary

    Prop Flange.JPGAlternator.JPG
    Gary (Geek) Phenning
    Leavenworth (Not the Prison), WA
    Kitfox STi in Building Stage

  2. #2
    Senior Member Dave S's Avatar
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    Oct 2008
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    St Paul, MN
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    Default Re: External Alternator

    Gary,

    Maybe the instructions are a bit skimpy. What you identify as press fit bushings are technically known as collar nuts (with 8 mm threads). The best way to install them is to have the entire prop and aluminum prop spacer assembly in place - using the prop bolts the collar nuts can be seated through the aluminum alternator pulley hub, the engine prop flange and aluminum spacer by tighten the bolts incrementally around the prop hub like you would when tightening a wheel on a car axle. The normal torque of the prop bolts is adequate to seat the collar nuts. The collar nuts should extend into the aluminum spacer between the engine prop flange and prop. Particular attention needs to be paid to assure the bolts don't bottom out on the threads and that they are long.

    In my particular installation, I used bolts which extended enough to permit 8mm jam nuts on the back side of the collar nuts as I couldn't find any prop bolts with drilled heads at the time.

    If the collar nuts need to be removed - a person can fabricate a little puller using an 8MM bolt of the right length and a piece of hardware (like a plumbing compression nut of the right size plus a washer) over the collar nut. A person should never be tempted whack them out with a hammer and punch.

    I think one of the reasons for the skimpy instructions with the alternator kit is the many options people could use on their prop/hub assembly. I found hunting through Kitfox final assembly instructions for the prop, plus the prop instructions, plus the spinner instructions, plus the alternator instructions helped.

    Hope that helps some.

    PS - be sure the pulley is slipped over the end of the gearbox before pulling the collar nuts into the flanges.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  3. #3
    Senior Member
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    Default Re: External Alternator

    "Hope it helped some"? Dave your answer was exactly what I needed to know. Thank you so much!!

    Gary
    Gary (Geek) Phenning
    Leavenworth (Not the Prison), WA
    Kitfox STi in Building Stage

  4. #4

    Join Date
    Oct 2021
    Location
    Carson City, NV
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    9

    Default Re: External Alternator

    Do you have some pictures of the assembly installed?
    Thanks
    John

  5. #5
    Senior Member
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    Nov 2019
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    Default Re: External Alternator

    Is this what you're looking for?

    Alternator.jpeg
    Gary (Geek) Phenning
    Leavenworth (Not the Prison), WA
    Kitfox STi in Building Stage

  6. #6

    Join Date
    Oct 2021
    Location
    Carson City, NV
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    9

    Default Re: External Alternator

    Quote Originally Posted by Geek View Post
    Is this what you're looking for?

    Alternator.jpeg
    Thanks, John

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