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Noticeable vibration at 200+ hours 912iS Sport

in 912iS Technical Questions 9 years ago

  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 5 years ago

    I replaced my old gearbox with the new box containing the extra oil jet and other modifications. This is a ser# 74000 + gearbox. I had the old gear box re-shimed at 175 hours or so. Joe at Lockwood said the vibration would return, and he was right. I decided to go ahead and have the gearbox upgraded to the new version at 300 hrs. The results put to rest the only nagging negative of the 912iS. So far the engine is smoother through the entire RPM range and there is no hint of a vibration at any speed or throttle setting. This was not a cheap fix as Rotax wasn’t even giving Lockwood a break on their own engines. I did get a fair “buyback” from Lockwood. This vibration is not a failure mode so there doesn’t seem to be a reason for Rotax to pop for the new series box. I’ve got over 40 hours on the new gearbox and I’m confident I will not be seeing the vibration returning. New engines I’m sure will be delivered with the improved gearbox. With that said, I would not hesitate to recommend the 912iS going forward.
      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 5 years ago

    bobzz,

    I'm trying to pick the correct part number for the new 912iS gearbox.

    My 2016 912iS delivered some large metal flakes on the mag plug at a recent 125-hour oil change; subsequent removal and inspection points to replacement.

    I'd like to replace it with the new design box. The Rotax parts list shows the following part numbers:

    893341 - Gearbox Version 2
    893346 - Gearbox Version 3

    There is no indication in the latest parts list indicating how to differentiate these part numbers, and I've been unable to get an answer through Rotax-affiliated distributors. Version 3 is intuitive, but maybe it is for a specific application?

    Appreciate any help you could provide in pointing toward the new-design gearbox part number!

    Tom
      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 5 years ago

    Tom, my new gearbox is p/n 893341 version 2. This a serial number 74000 gearbox. The gearbox 893340 and 893345 are for straight 912iS..... 843341 and 843346 are for 912is Sport models. The difference between version 2 & 3 seem to be in the prop shaft. If your engine is new you probably have a 912iS Sport. I’m not sure what the difference is between the prop shafts are but if the gearbox serial number is a 74000 or above, you have the new gearbox.
      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 5 years ago

    Thanks, that is very helpful...

    I now understand that Version 2 is for the 'hollow' prop shaft, while Version 3 is for the hydraulically adjustable prop.

    My gearbox SN is 66198, before the new oiler design. Although it is not indicated on the parts list, I think a new order for gearbox 893341 will automatically include the dog hub oiler (assuming it is SN 74000 or newer, versus some NOS unit off the shelf).

    Attached is a photo of the metal flakes on the mag plug at the last oil change; we found their origin on gear inspection.

    Tom
    125HROilChangeMagPlug.JPG (You do not have access to download this file.)
      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 5 years ago

    Wow! Those are some rather large chips! Yes the 893341 gearbox will include the ser# 74000 series “oiler”. I have 50 hours on the new gearbox and it’s smooth as silk. No vibration whatsoever.....
      
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