G: Gearbox (Single - Burman) Burman Box Again

brian gains

Well Known and Active Forum User
VOC Member
Martyn; the emphasis of how I arrived at my figure for play on the layshaft was very much by 'extrapolation' and by no means direct empirical evidence. By mounting in 'V' blocks I don't think I would glean any more than is in the youtube vid's you already highlighted.
Vibrac; I'll try and seek out the Ron Kemp article in the archives before I try my own multiple porting exercise with a lump hammer %@#!
seriously, thanks for the suggestions, as I've said previously this is what makes the VOC forum an invaluable asset in disseminating knowledge and experience. In addition. thanks to a couple of generous offers from other Vincent yeoman I hopefully will be able to move this saga forward. Anon.
 
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Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
The VOCSC I believe has an open framework for mounting twin g/box internals into to check operations, also the South London boys have a similar rig, we just need to find uncle Ron's Comet G/box rig.
 
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brian gains

Well Known and Active Forum User
VOC Member
has this been flagged up previously;
from Stevens - 'Know Thy Beast' pg100.
" layshaft pinions....The longer bush takes the 34T (1st gear) pinion and should be at the clutch end of the box".

while Richardson - 'Vincent Motorcycles' 3rd edition pg 100. " the layshaft is sub-assembled with the longer splines away from the operator (therefore with shorter bush and nearer to the clutch basket) and order of pinions right to left 3rd gear 24T, 1st gear 34...."

i'm taking that the perspective in both these descriptions is as being astride the machine facing forward. Did Stevens mean by "clutch end " the operating lever end, if there were further editions was this corrected or is it Richardson's description of the orientation of the longer splined end that is in error.
I'm inclined to believe Richardson gives the correct description.
 

brian gains

Well Known and Active Forum User
VOC Member
Two points; the layshaft can be loaded with gears either way, long splined end or short splined end towards clutch, the 'math' does not help you.
The other point is these are considered the two definitive publications as reference for finding your way around a Vincent, it would therefore be helpful if errors were flagged up for general awareness.
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
has this been flagged up previously;
from Stevens - 'Know Thy Beast' pg100.
" layshaft pinions....The longer bush takes the 34T (1st gear) pinion and should be at the clutch end of the box".

while Richardson - 'Vincent Motorcycles' 3rd edition pg 100. " the layshaft is sub-assembled with the longer splines away from the operator (therefore with shorter bush and nearer to the clutch basket) and order of pinions right to left 3rd gear 24T, 1st gear 34...."

i'm taking that the perspective in both these descriptions is as being astride the machine facing forward. Did Stevens mean by "clutch end " the operating lever end, if there were further editions was this corrected or is it Richardson's description of the orientation of the longer splined end that is in error.
I'm inclined to believe Richardson gives the correct description.

The long side(7/8") goes into the drive side of the gearbox.
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
Well the math. may not help, but one gear on the layshaft is wider than the other. Sorry, I thought this was obvious, my mistake. I agree about the errors in publications. I try to help when I can. I'm up to 68 pages of "Conversation" helping a mate put a Comet together. Anything you want to ask, go ahead, usual disclaimers about human frailty apply. Cheers.
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
Orright, now you've wound the clockwork up I'll continue in a series of short jerky movements. I pulled out a new layshaft and gears. I am unwilling, even in the pursuit of absolute accuracy, to pull it apart, but I took the following rough measurements using a vernier caliper. FROM CLUTCH END: bearing register on shaft (length), .760". Width of 21 tooth layshaft gear approximately .926", and the spline length corresponds. From the kickstart end, width of bearing register on shaft .949", width of layshaft 3rd. gear .700" and the spline length corresponds, (well it sticks out about.005"). While you've got it apart, Brian, check the cross-drilled lubrication holes on the two central free running gears. These are often blocked with grease from the 50's! Most post war boxes have these two gears running on bronze sleeves. Oilite or similar is used for the output gear bushes and the two top-hat bushes that the layshaft runs on. DO NOT use bronze for these, it could be fatal. I now have a modern (1985) Japanese bike and am amazed at the detail contained therein; wiring routes, exhaustive torque specifications, using choke only below 20° C and so on. saying that I've only noted one glaring error in "Richardson" which is the wrong placement of ET98 on the cam followers. The illustration in "Richardson" for the gear placement is correct, however he is in error with his description as the second gear layshaft is "free" and the small gear, 21 teeth is fixed on the shaft and is in constant mesh with the 33 tooth main driving gear. I hope this helps someone out there.
 
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