G: Gearbox (Single - Burman) Burman Gearbox advice needed.

timetraveller

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The late Nick Wingrove's son, Jason, is now riding his father's Comet. He phoned me Suday evening to say that he had broken down about a couple of mile from me and could I help. I went out to find him and the lower nipple had pulled off the clutch cable. He has now bought and fitted a new cable but there is a further problem. There is no drive. I have just been over to see if I can help and I find myself out of my depth. The primary drive seems to be correct and I can kick the engine over on the kick starter, which to me indicates that the clutch is holding. The rear chain is intact as are the rear brake drums, sprocket etc. To start with the clutch cable was incorrectly adjusted as there was no free play but I sorted that out. I have tried moving the rear wheel by hand while Jason changed gear and at no point is there any sign of any of the gears trying to engage. The kick start cover was taken off and the pinion which is rotated by the gear change lever was moved with the aid of a set of pliers and it is just the same in that spinning the rear wheel never engages any gears no matter how the gear change shaft is rotated. I am not familiar with the Burman gear box so if anyone has any advice or can think of something else to check that will avoid taking the bike apart to remove the gearbox then that would be very helpful. Thank you in advance
 

Simon Dinsdale

VOC Machine Registrar
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VOC Forum Moderator
I have heard of some Burman final drive sprockets being made of the wrong material in the past and so stripping their spline in the final drive sprocket itself . End result is it just spins on the output shaft which would give the results you are seeing.
Just a thought.
Simon
 

timetraveller

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No unexplained noises when I spinn the rear wheel. Would you expect some noise if the sprocket was spinning on the shaft? He was riding it until the clutch cable went and had not noticed anything untowards. However, it is his first bike so he does not have years of experiencing the kind of things we discover on Vins.
 

Chris Launders

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Racking my brain something reminds me of hearing of a Burman box where whatever retains the final drive bearing failing allowing the final drive gear to move out of engagement. Just something I recall from somewhere.
 

Bill Thomas

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Racking my brain something reminds me of hearing of a Burman box where whatever retains the final drive bearing failing allowing the final drive gear to move out of engagement. Just something I recall from somewhere.
Yes I had the case break up where the circlip goes, But I still got home in 3rd gear.
 

b'knighted

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On the way to a Kenmore Rally, probably late 70s, I had a problem when the bronze of a selector fork picked up on the steel groove it was running in and flowed around the slot until it was all below the shaft and could drop out.

The replacement fork that I managed to source from a friend of a friend of a total stranger didn’t work for long until it picked up and did the same. I should’ve replaced the sliding gear.
 

shortun

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If the cover was taken off it's probably the ratchet type plate that is held by two locating pins on the gear lever mechanism has disengaged or maybe has the mechanism been timed as in the handbook. I put all the mechanism in place removed from the cover then fit the cover then fit the locating bolt last.
 

brian gains

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VOC Member
decomp' cable can be used as 'get you home' repair, have done so and think it is pointed out in one of 'the books'.
do a search and find my Burman woes,2019?. I went in looking for one issue of no 4th gear drive but found several others.
Slight solace, the Burman can be removed with removal of primary and associated g'box bracketry. Bit of a wrestle but after several remove/replace procedures it becomes quite straightforward, accepting bruises to all parts concerned.
 
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