Author Topic: Dragonfly gearbox knocking  (Read 1781 times)

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Offline andy1303

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Dragonfly gearbox knocking
« on: 12 Oct 2015 at 20:53 »
Hi All,

Last weekend I attempted my first test ride on my Dragonfly. She now starts and ticks over fine, however when I engage first gear and let the clutch out she starts to pull away then I get a really loud knocking from what I think was the left hand side of the bellhousing/gearbox. Initially I thought it might be clutch adjustment but no joy there. There is no noise when the bike is put up on chocks and run in gear.

I've now dropped the engine out and split the gearbox from it, and there seems to be a serious amount of play between the input shaft and final drive when in first gear, and the other gears are difficult to engage. Is this normal? Either way, can anyone recommend a direction to start looking?

Thanks

Andy

Offline eddie

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Re: Dragonfly gearbox knocking
« Reply #1 on: 12 Oct 2015 at 21:38 »
Andy,
         It sounds as if the final drive shock absorber is riding over the top. With the spring and retaining plate removed, turn the sprocket to see how far the cam lifts - it should lift higher than the end of the centre sleeve. If it does, all is OK. If not, you may need to fit a thin spacer over the sleeve so that the combined height exceeds that of the sleeve. You should then have a large dia spacer (same dia as the boss on the cam) x about 1/2" thick, then the spring retaining plate. The 1/2" dia bolt that goes right through the final drive shaft should then be done up tight, and a split pin fitted.
  The reason you may need to fit the thin spacer is that Mr Douglas changed the length of the sleeve at some point during the production run, and you may have a mismatch of cam and sleeve.
  Don't worry about the backlash in 1st gear - this is normal, it makes gear selection a bit easier on engine speed gearboxes. If you turn the input shaft as you try to select other gears, it should change easily.
  Hope this helps,
                  Regards,
                                Eddie.

Offline andy1303

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Re: Dragonfly gearbox knocking
« Reply #2 on: 13 Oct 2015 at 21:29 »
Hi Eddie,

Thanks for your thoughts. I'll take a look as soon as I can. Looking at the exploded diagram for the final drive, would you recommend the spacer go on the gearbox side of the sprocket or the outer side of the shock absorber cam? Will I have to remove the whole final drive assembly to tighten the nut back on to the shock absorber bolt?

Many Thanks

Andy

Offline andy1303

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Re: Dragonfly gearbox knocking
« Reply #3 on: 15 Oct 2015 at 21:38 »
I'm doing a lot of learning with this Dragonfly.

In case anyone is following this that doesn't know, the shock absorber bolt goes pretty much the width of the gearbox and there's a cap on the opposite side of the gearbox to the final drive which unscrews revealing the bolt head. Frustratingly this means I probably didn't need to remove the whole engine from the bike since on close inspection, it looks like the castle nut holding the shock absorber assembly on wasn't tightened on fully, meaning that there was enough play for the cam to slip. The castle nut was tightened sufficiently to fit a split pin but when tightened fully the split pin would not have sat correctly. The addition of another washer has spaced the castle nut out to the correct place.

The only benefit is that I can now see the centre stand easily, and it looks as if I should be able to resolve an issue I have with it.

Next step... get the engine back in, and have another go at a test ride....

 

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