Author Topic: Dragonfly Clutch drag  (Read 4927 times)

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Offline MikeW

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Dragonfly Clutch drag
« on: 13 Apr 2010 at 01:09 »
Hi,
I am new to the Forum, located near Romsey Hampshire.
I have just built a 'Fly engine/gearbox from bits collected over the last 25 years or so.
Having fitted it in the bike, it started first kick (to my suprise!) and the motor seems good (so far), but no matter how I try to adjust the clutch, it drags. Is this common?
Could I have done something stupid?
Also, despite using new gaskets/fibre washers throughout, the oil filter cap still leaks. Does this need a sealant normally?
Any advise appreciated.
Regards
Mike W

Offline eddie

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Re: Dragonfly Clutch drag
« Reply #1 on: 17 Apr 2010 at 07:12 »
Mike,
         There could be all sorts reasons for the clutch dragging - maybe a distorted friction plate, springs of unequal length, a distorted pressed steel outer plate, the bronze bushes thru' the flywheel may be dragging, or the thin spacers missing from one or more of the six studs. Regarding the distorted plate - I have found several where the central thrust pad does not run true with the rest of the plate. There may also be a simpler answer to the problem - the 'Doherty' type handlebar levers came in 2 types with different distances between the pivot and the hole for the nipple - if you have the short variety, it may not be giving enough lift. Just as an experiment, try adjusting out all the free play, and see if this cures the problem - but don't run the bike for any length of time like this, or you will end up with premature wear of the clutch release bearing.
                                  Regards,
                                         Eddie.

Offline MikeW

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Re: Dragonfly Clutch drag
« Reply #2 on: 17 Apr 2010 at 21:16 »
Eddie,
Many thanks for a comprehensive reply, it gives me several things to explore. I carefully checked that all springs were even length and the spacers were on each stud when I assembled and thought I had made sure the bronze bushes were free (but as they were not when I started, perhaps they are still dragging?). I think the Doherty lever is probably not the problem as I had already tried taking all adjustment out, but if anything, it was worse?
I will now try and work through your remaining suggestions.
I also now have a problem of not always going into top gear first time or occasionally jumping out of top even when it does, Does this indicate a gearbox strip or possible selector adjustment.
You probably gather, Douglas machines are a total voyage of discovery for me though gremlins aside, an enjoyable one!.




Quote of previous post removed - Dave, 18th April
« Last Edit: 18 Apr 2010 at 10:58 by Dave »

Offline Tom Doran

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Re: Dragonfly Clutch drag
« Reply #3 on: 18 Apr 2010 at 12:03 »
MikeW,
This may sound an entirely silly question but what gearbox oil are you using?
I only ask because i recently bought a T35 which had similar problems but it had the gearbox filled with what appeared to be 20 grade engine oil, once the hypoid was in it was fine.

TomD

Offline eddie

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Re: Dragonfly Clutch drag
« Reply #4 on: 18 Apr 2010 at 13:06 »
Mike,
         Quite a few of the late Dragonflies suffered from poor engagement of top gear - I think the tooling was getting a bit tired, so some machining was getting out of tolerance. If the dogs are not meshing deep enough, this can be overcome by fitting a 1/16"shim behind the input shaft bearing and it's retaining plate. Unfortunately this does mean having the 'box out. This moves the whole input shaft assembly back to deepen the mesh. Rather than disturbing the whole engine unit, I prefer to remove the toolbox and take out the swinging arm bolt - then just the 'box can be removed.
                              Regards,
                                           Eddie.

Offline MikeW

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Re: Dragonfly Clutch drag
« Reply #5 on: 18 Apr 2010 at 21:50 »
MikeW,
This may sound an entirely silly question but what gearbox oil are you using?
I only ask because i recently bought a T35 which had similar problems but it had the gearbox filled with what appeared to be 20 grade engine oil, once the hypoid was in it was fine.

TomD
Thanks Tom,
I had filled it with 90 gear oil so will try Eddie's suggestion re end float on main input shaft.
Thanks for your input.
Regards
MikeW

Offline MikeW

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Re: Dragonfly Clutch drag
« Reply #6 on: 18 Apr 2010 at 22:28 »
Mike,
         Quite a few of the late Dragonflies suffered from poor engagement of top gear - I think the tooling was getting a bit tired, so some machining was getting out of tolerance. If the dogs are not meshing deep enough, this can be overcome by fitting a 1/16"shim behind the input shaft bearing and it's retaining plate. Unfortunately this does mean having the 'box out. This moves the whole input shaft assembly back to deepen the mesh. Rather than disturbing the whole engine unit, I prefer to remove the toolbox and take out the swinging arm bolt - then just the 'box can be removed.
                              Regards,
                                           Eddie.
Thanks Eddie,
If I try this, Will this reduce the mesh on other gears? Is it possible to establish how far the dogs go in without taking off selector assembly.I assume taking selector assy off means there is then no way to see how far they are engaged by the gear lever? Finally, is the bevel gear engagement at the rear of the shaft affected by shimming behind the front bearing please?
Regards
Mike W

Offline eddie

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Re: Dragonfly Clutch drag
« Reply #7 on: 19 Apr 2010 at 07:57 »
Mike,
        The mesh of the indirect gears will not be affected by this shimming as you will only be adjusting the position of the input shaft. If you remove the gear indicator, you should then be able to remove the side plate from the gearbox, leaving the selector quadrant in place. Then you will be able to select each gear and check the mesh of the dogs for 2nd, 3rd and top gear (1st gear cannot be seen as it hides behind the casting). You will probably find top only meshes by about 1/16" - which is not enough. Do not try to make any adjustments to the actual selector forks as this will only result in you losing from 3rd gear what you gain in top. To shim the front bearing, you will need to remove the front plate (figure 8 shape) and remove the coupling. These can be stubborn - if you don't have the use of a special puller, the method I find works well is to undo the nut a couple of turns then keep squeezing the coupling in the vice, moving round 1 spline each time. Eventually it gives up and releases. With the coupling removed, undo the 4 screws on the inside of the cover - you will then be able to withdraw the input shaft and the loose rollers. With the cover warmed, press out the outer bearing track and hardened facing washer. Make up a 1/16" shim to fit behind the facing washer, and then reassemble as before. You will now find the outer track stands proud by the thickness of the shim. Make a 2nd shim to fit around the outer track and to the same shape as the retaining plate. Refit the input shaft and loose rollers - then check that the coupling will still fit on the front of the shaft (you may have to tweak the oil throwers so that they do not rub on the front of the cover plate - in some cases, light machining of the cover may be needed). Refit the front cover and check that top gear can be engaged without the dogs bottoming out.
     Whilst doing this, some members have taken the opportunity to do a bit of machining and fit 'a proper oilseal' to the main shaft, but bear in mind that this is the only place the Dragonfly box can 'breathe' as there is no breather in the filler plug (as on the Marks). If other breathing is not provided, oil will find it's way out from any other weak point.
          Get back to me if you have any problems.
                             Regards,
                                     Eddie.

Offline MikeW

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Re: Dragonfly Clutch drag
« Reply #8 on: 19 Apr 2010 at 23:03 »
Eddie,
Thanks very much,
I think I can follow this very helpful explanation so It will be "out with the gearbox" and hopefully I can sort the clutch and gearbox in one hit?
Thanks for sharing your obvious extensive experience. It moves my steep learning on a pace!
Best regards
Mike



Quote of previous post removed - Dave, 20th April
« Last Edit: 19 Apr 2010 at 23:29 by Dave »

 

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