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G: Gearbox Burman Gearbox advice needed.

timetraveller

Well Known and Active Website User
VOC Member
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
 

nkt267

Well Known and Active Website User
VOC Member
I think i would go for wiggling the box out through G50/1 as once the inner case is off the RFM looses it's support as does the engine. you are almost all the way to splitting the bike..good chance to practise your Anglo saxon if you go this route but it is not impossible..i've done it a few times now..
 

highbury731

Well Known and Active Website User
VOC Member
The engine shocker will have to come
Off. I would use a chain wrench to stop the engine turning while undoing the nut.
I put the chain wrench around the body of the shocker.
If I have to remove the ESA nut, or otherwise lock the engine, I find a rope down the plug-hole works well. Just make sure the valves are closed, or you will not be happy....
Paul
 

Robert Watson

Well Known and Active Website User
VOC Member
I have had EXACTLY that problem, not once, but twice with my Comet. Gearbox drive sprockets had NOT been hardened.

Also can be caused by the drive sprocket nut not being securely tightened allowing it to move ever so slightly then 'worrying' away at the splines on the sprocket. Can even damage the splines on the gearbox output gear shaft.

The give away is that you can kick start the motor, you can change gears but nothing happens at the back wheel - its just like a broken drive chain - till you wake up that the drive chain is intact.
Or the rear drum breaks just on the step down from the from the rim to the hub, and neatly enough that the sprocket and drum look just fine. There you are well south of Perth in the Margaret river wine area and quite a few miles from anywhere and it's 11 in the morning and starting to get rather warm. Thinking the worst (this on a twin) about what has failed in the gearbox. with the rear mudguard flap up and on the rear stand you just happen to give the back tire a spin, and hesitate. Did that chain really not move. Do it again. Say Eureka out loud, assure the wife you will be mobile in 20 minutes, tell the guy that pulls up in the Mustang that you are good to go, Turn the back tire around having had the foresight to run the same size sprocket on both sides so no sprocket changing required, And shortly head off to Adelaide where a new rear sprocket will be waiting. Tell me on what other motorbike that is possible?
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Vincent's are great things to have. had the same in NZ at Christchurch, but I had assistance from Russle Byfield that I spent three days with him and the two guys that ran a bike shop, swapped the steel brake drums around as bolt holes were slotted. Alan bolts were fitted (into new holes) from inside to out as radius of steed pressed drums hexagon bolts didn't fit squarely enough, spring washer and nylocks and it just clears the brake torque arms. Harvey shipped the bikes home after he toured NZ in 2019 since then the rear wheel has been put on the "A" Comet and a new wheel built for the twin with WM4 x 21"!!? the same as the front with SPEET T.L.S.brakes.
 

timetraveller

Well Known and Active Website User
VOC Member
Thanks guys but it is not the rear wheel, a brake drum or anything at that end. I checked all that. Jason is busy this weekend so next week we should find out what the problem is. Had a long talk to Clive Smith this evening who phoned me about another matter. He has a Comet as well as a twin so it was useful to exchange some ideas.
 

vibrac

Well Known and Active Website User
VOC Member
You can take the inner off without doing anything with support I just did it last year to fit an electric start and of course bear in mind that includes one side of the RFM pivot unsuppoted
 

brian gains

Well Known and Active Website User
VOC Member
could have had a 'socially distanced' wrench session yesterday, had a 100 mile pootle down to Rye and back skipping over Eastbourne.
seriously, Eastbourne is about 1/2 an hourish south of me. If he needs an extra set of hands and has read through my posts on my Burman box drama and thinks i may be of use i'm glad to help. Other suggested reading uTube: Burman box disassembly and rebuild, also Arial tech officer (?) description of Burman box gear drive train.
I'm not a mechanic but lack of enthusiasm has not stopped me yet.
 

timetraveller

Well Known and Active Website User
VOC Member
Hi Brian, tht is a very kind offer. I will PM yoiu with my phone number and we can discuss what we can do. If you can point me in the direction of your 'Burman Gearbox Drama' that sounds useful as well. I did do a search for it in this forum but nothing came up.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Thinking back to when I was a lad,
Went from working on Vincents to Cars !, Didn't have a clue !,
Every time another young mechanic went past my bench, I asked a question,
Just thinking , If Jason was on the Forum and can Take / Post photos ??,
There is a lot of help could be given,
Maybe a long job, But that can happen with Vincents !.
 

timetraveller

Well Known and Active Website User
VOC Member
Thanks Bill, Jason's dad, Nick Wingrove, was a member for many years and one of the most helpful people you could wish to meet. Jason is doing his best, starting from nothing, to keep his dad's bike on the road and being used. Nothing to photograph at the moment but let us see what happens next week.
 

brian gains

Well Known and Active Website User
VOC Member

not sure how these link thingamies work this was posted around Sept' 27th 2019 the a month or so later another thread was started which I can't seem to find.
 

Martyn Goodwin

Well Known and Active Website User
VOC Member
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
Extensive BURMAN resource available in the OVR archives. File is called "Burman Information.zip"

Try this link https://drive.google.com/drive/u/1/folders/0Bx6LgdbZWDhzeHdWcW1VUUE2RG8
 

timetraveller

Well Known and Active Website User
VOC Member
First of all. many thanks to all who offered advice. I spent the afternoon helping Jason to take things apart. In the end we took out the gearbox having had to remove the return oil feed line, the battery carrier and lower the exhaust pipe and silencer. The problem was as diagnosed by several of you. The inner splines of the final drive sprocket had dissapeared, totally so top marks to those of you who predicted this would be the case. The part of the main shaft on which this is located has a male sprocket and the teeth on that, although present, have wear at their ends where the final drive sprocket has chattered. Why this should become evident at the same time as the cluch cable broke is one of those things that probably require a belief in wichcraft rather than science. We have dismantled the whole gearbox and I left Jason cleaning all the parts in petrol so that we can inspect them tomorrow. Most seem to be in good order but at least one pinion has two adjacent teeth malformed at their very ends as though something has gone through them at some time in the last seventy years.
 
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