Just got my gearbox from its 600hr rebuild/service by my Eastern Canada Rotax service centre, who reported that all the internals were good and within spec.  But now I have noticed that the Dog-clutch is squeaking when hot. When cold, and the crank is locked, it measures within spec, feels right, and makes no sound when rotating the prop back and forth through the dog's 15 or 30deg flat spot (can't remember which, but it's a current style clutch assembly).  But when the engine is hot I can hear a squeak at idle (when the dog is in play), and when the hot engine is stopped and the prop is moved by hand, the dog grabs and slides and groans... it's not smooth. It has about 20hrs on it since the rebuild, and noticed this issue around the 10hr mark. Once cooled, it is smooth and quiet again.

I would assume this performance is not good/acceptable, but I cannot understand what could have changed in the service/rebuild.

I always run the rotax spec'd aeroshell sport +4, and mogas (no ethonol).

The mag plug looked good, and nothing of concern was found in the oil filter.

Any advice/experience greatly appreciated.

Cheers, Pete


  • Re: Dog-clutch hot squeak

    by » one month ago

    This can be normal and usually will go away after a while. Many people report this all the time especially on new engines with of course a new gearbox. Give it some time.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

  • Re: Dog-clutch hot squeak

    by » 4 weeks ago

    Hi Pete


    It may be that the dog to ramp position of the 3 contact points was not put exactly in the same ramp.  If that is the case it will wear in and should stop.  If your idle speed is a bit low this may contribute to the issue also as the movement is more at lower RPM.  It should completely stop once you get past idle.  I don't know the exact spec but the friction setting of the spring washes, set by shims when going back together, usually likes to be in the high range compared to the min to max spec.  I like to set them always as near max as possible when shimming as the box will always wear down the springs and give you less friction setting over time.  



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