Author Topic: Dragonfly idler gear, etc.  (Read 2334 times)

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Offline triton999

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Dragonfly idler gear, etc.
« on: 08 Apr 2014 at 15:47 »
Can anyone help an inexperienced Dragonfly owner with my problem.  I've removed the "V" shaped idler gear strap and found it to be bady scored by the gear.  When about to replace it, I've realised that there appears to be nothing to prevent it being screwed back against the gear.  I've l;ooked at the parts list book, Plate 2, and seen that the idler spindle (item no. 4) has a hex head inside the crankcase.  Does this have a corresponding recess in the case to prevent it turning?  If so, is it possible that the spindle has come out of this recess and, therefore, not protruding far enough so that the shoulder of the spindle holds the strap away from the gear?  Hope this question makes sense.  Anyone got a photo/diagram of the inside of the crankcase?  Help....please.

Offline eddie

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Re: Dragonfly idler gear, etc.
« Reply #1 on: 08 Apr 2014 at 18:34 »
           As you say, the 2 idler spindles have hex heads - these locate by 2 of the flats into slots milled across the inside of the crankcase. The slots are about 3/16" deep, so if the heads are not properly located in the slots, it would be impossible to fit the nuts and insert the split pins. On the Dragonfly, the timing gears are wider than on the Mark series, resulting in no boss to the outside of the gear. This in turn causes the gear to rub on the strap when there is any wear in the bore of the gear or on the OD of the bronze bearing bush (which should be about 5 thou longer than the gear, so that the gear still rotates when everything is tightened up). To prevent further wear to the strap, you could try inserting thin washers on the 2 studs and the spindle before fitting the strap - but make sure the washer on the spindle is large enough in diameter to provide a bearing surface - preventing any increase in the end float on the idler gear. Make sure the nuts on the spindles are adequately tightened and that the shoulder on the spindle is below the end of the bronze bush, thus ensuring that the nut actually clamps the whole assembly in the crankcases. Loose idler spindles are not unknown on Dragonfly motors.