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Rotax 912 - Starter Motor Attachment

Paul Willett

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We recently removed the Starter Motor on our 912 to check on a suspected oil weep at the seal.


After replacing we tightened the M5 Hex bolt using a torque wrench. After snapping it we obtained a replacement and then proceeded to snap it too - at a setting of just 10nM Torque.


Has anyone had to do this - and managed to find a suggested torque from Rotax?


Bert Flood is looking in to it for us as well, but perhaps someone else has been through this?



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Guest micgrace



In my experience, when on final tightening if any "chattering" on the hex bolt, will snap it like a carrot. I'm not sure if rotax recommend it, but a slight dab of oil on the two mating services removes this problem.


From observing/training different mechanics as well, I notice they go out of their way to have everthing squaeky clean, which is great. But forget to use lube on assembly of minor parts.


Some manufacturers specify dry threads and others oiled threads. Need to confirm from overhaul manual to be sure. Plus other deviations.


Myself, as a rule of thumb on an uncertified engine would lubricate the threads and mating surfaces. Only way you can really be sure of specified torque values. Plus chase the threads as well (tap & die)


Some other manufacturers are using a method I, personally don't like. Bring bolt up to a low torque value, then tighten bolt a number of degrees. (usually, 90*) Although it makes perfect sense.


Some ideas, Micrace :)


disclaimer: General information only. Check with relevant manufacturers overhaul manual first.



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