Author Topic: Dragonfly Engine Nut or not? Generator rotor on crankshaft.  (Read 2761 times)

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Offline BrmBrm

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I've removed my generator cover to check the breather.
I can see the generator rotor.
Protruding from the rotor is a shaft end with a thread.
The shaft end fits in the generator cover bush.
There isn't a nut on this thread, should there be?
Plate 1 of the Dragonfly parts manual shows a spacer, tab washer and 5/8" BSF Nut. Should these be visible when the rotor is fitted?
Many thanks.

Offline eddie

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Re: Dragonfly Engine Nut or not? Generator rotor on crankshaft.
« Reply #1 on: 07 Mar 2015 at 18:08 »
Yes, there should be a nut on the end of the crankshaft (and visible with the generator cover removed). Unfortunately, Mr Douglas fitted a normal nut with a RH thread - which, if slack, can unscrew and jack the generator cover off the timing cover. (Look carefully for any signs of damage to the timing cover - the original generator cover may have been replaced if badly damaged). As you say, there should be a 5/8"BSF nut on the shaft - but it is only a thin locknut - from memory, only about 3/8" thick, and retained by a tab washer. For the nut to come off, it can only fall into the space behind the generator stator - make sure it (or the tab washer) is not still lodged in there, as they will eventually short out the coils.
 If you have any suspicion that the nut or tab washer could have dropped into the timing chest, drain the oil and remove the timing cover to make sure it they are not about to get tangled up with the timing gears. Whilst you have the cover off, check that the nuts on the idler spindles are also tight - loose idler spindles are quite common on Dragonflies!

  Regards,
                Eddie.

Offline BrmBrm

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Re: Dragonfly Engine Nut or not? Generator rotor on crankshaft.
« Reply #2 on: 07 Mar 2015 at 19:41 »
Many thanks Eddie (again).
Good news - no signs of contact or damage inside the cover or at the timing gear teeth.
Good news - no sign (yet) of the nut, tab washer or spacer.
Perhaps the previous owner found some way to lock the rotor to the crankshaft  :)
Dave

Offline eddie

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Re: Dragonfly Engine Nut or not? Generator rotor on crankshaft.
« Reply #3 on: 07 Mar 2015 at 21:37 »
Dave,
         Maybe, the generator rotor has been Loctited in place - but that wont apply any clamping force to the timing gear, so it is likely to rock on the key until it eventually breaks loose! - in which case, the valves are likely to strike the pistons and cause even more damage.

    Eddie.

Offline BrmBrm

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Re: Dragonfly Engine Nut or not? Generator rotor on crankshaft.
« Reply #4 on: 08 Mar 2015 at 11:40 »
Thanks Eddie,
Just so I can be sure :-
Where does the Distance Piece (ITEM 9 Plate1) go relative to the rotor,
front of the rotor (generator side),
in the bore of the rotor,
or behind it (Crankshaft Gear side?
Sorry to ask again, at the moment I'm not sure if I have the Distance Piece fitted or not.
Many thanks,
Dave


Offline eddie

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Re: Dragonfly Engine Nut or not? Generator rotor on crankshaft.
« Reply #5 on: 08 Mar 2015 at 16:58 »
Dave,
         The parts on the end of the crankshaft (in order of assembly) are: oil retaining plate, timing gear (with a key), distance piece, generator rotor (with another key), tab washer, and finally - the retaining nut.
   If the distance piece was missing, the generator rotor would foul the ends of the idler spindles.

  Eddie.

Offline BrmBrm

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Re: Dragonfly Engine Nut or not? Generator rotor on crankshaft.
« Reply #6 on: 08 Mar 2015 at 21:42 »
Thanks Eddie,
So for now I'll just fit a tab washer and nut.
So now I know a bit more about the Dragonfly.
Best wishes,
Dave