Jumping out of first gear.

vince998

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VOC Member
Hi all,
My D shadow has been playing up recently by jumping out of first gear under acceleration.
The steeper the hill or heavier the load, then the faster it jumps out.(i´ve just moved to a rather hilly/twisty part of germany, and having to short shift into second on tight hairpin uphillers is doing nothing for the vins rocket like reputation :))
I´ve tried adjusting the gear selector mech, i´ve changed the camplate plunger & spring, all to no avail.
If i try and hold it in gear with my foot, then my foot is forced down and out it jumps again.
My powers of deduction (or should that be destruction) say that the engaging dogs on the end of the double gear are probably tapered, and with increasing load, the double gear is pushed across so disengaging first.
Before i go tearing everything apart (i´ve just polished it :(), has anybody any other ideas/theories?
Thanks
 

Bill Thomas

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VOC Member
Might be worth checking the cam spindle is tight in the top of the box,
Under the dynamo. Good luck Bill
 

vince998

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VOC Member
cam spindle

Cheers Bill, that´ll go on the "things to do" list
To be quite honest, i´d totally forgotten that.
All other gears work spot on, and gear selection is easy and smooth, cold or hot.
 

vince998

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VOC Member
Cheers Bill, that´ll go on the "things to do" list
To be quite honest, i´d totally forgotten that.
All other gears work spot on, and gear selection is easy and smooth, cold or hot.

I´ve checked the cam spindle, and everythings as it should be (its lockwired anyway!!!)

Has anybody else any ideas?
No idea to stupid :)
I´m saying this because i know that if i strip the gearbox down, i´ll find a miriad of small points that aren´t quite right (the last time the gearbox saw daylight was probably 20 - 30.000 miles ago), and spend an absolute fortune putting them right.
With my old FJ1200, i can "flick it" and carry on riding, it doesn´t bother me, but with the vincent (it was my dads bike and i´ve got pictures somewhere of me as a baby in a sidecar next to it) i can´t leave alone unless everythings spot on.
This must be a generation phenomenon???
I know quite a few guys twice my age (and owners of vincent for decades) who are willing to flick and ride as i do my Yamaha.
I experienced this last time with the clutch. everything was worn out (but it still worked as it should, perfectly!!!) so i spent many hours boring/sleeving spring plungers, replacing parts worth a small fortune, because in my eyes it needed doing. Outcome? it still worked as it should (no better no worse!!:rolleyes:)
Come on guys, help me save money here :D
Thanks
 

clevtrev

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VOC Member
Maybe it`s never been in first gear, in it`s entire life. There`s quite a few out there that that is an occurrence on. Also some suffer from the same thing in top. The reason is the machining of the flats on the bevel gear, not quite right, slightly out of square to the bevel tooth centre line.
 

timetraveller

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VOC Member
Also when Dick Sherwin lost a gear several years ago at a rally in Scotland and came all the way back down to the south coast without one gear it was found upon dismantling that the spacing of the gears along the shafts was incorrect. I forget which gear it was but it was clear from marks on the dogs that one of the gears had never been fully engaged since the bike was new. It was necessary to insert a shim in the correct place to push this gear in-wards before the dog engagement was correct. There is much to be said for having a jig which mimics the gearbox housing so that prior to assembly in the bike one can do a dry assembly in the jig and check that everything engages as it should. I looked into making one, or a batch, of these several years ago and got all the dimensions etc but never got round to making any. My own feeling is that it would be useful if each section had one to be used as and when needed by the local members. However, there are several of the professional machine builders in the club who have such jigs and it is possible that there is no demand for such devices among the general club members. It is more than just the mesh of the gears which has to be checked. I have found large discrepancies between some gears and some lay-shafts and it seems that at different times different dimensions were used for the splines. Given the wrong combination either the bits will not go together or they are so sloppy that they should never be used.
 
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